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Nishimura B, Escalante J, Mezcord V, Tuttobene MR, Subils T, Actis LA, Pasteran F, Tolmasky ME, Bonomo RA, Ramirez MS. Human serum albumin-induced modification of Ton-B-dependent receptor expression in cefiderocol-exposed carbapenem-resistant Acinetobacter baumannii. Int J Antimicrob Agents 2023; 62:106950. [PMID: 37597787 PMCID: PMC11066775 DOI: 10.1016/j.ijantimicag.2023.106950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/09/2023] [Accepted: 08/05/2023] [Indexed: 08/21/2023]
Affiliation(s)
- Brent Nishimura
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Jenny Escalante
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Vyanka Mezcord
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Marisel R Tuttobene
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina; Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario, Argentina
| | - Tomás Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario, Argentina
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, Ohio
| | - Fernando Pasteran
- National Regional Reference Laboratory for Antimicrobial Resistance (NRL), Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, ANLIS Dr. Carlos G. Malbrán, Buenos Aires, Argentina
| | - Marcelo E Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Robert A Bonomo
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, USA; Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA; CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA
| | - María Soledad Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
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Islam A, Actis LA, Wilson TJ. Natural Antibodies Mediate Protection Against Acinetobacter baumannii Respiratory Infections. J Infect Dis 2023; 228:353-363. [PMID: 36951192 PMCID: PMC10420402 DOI: 10.1093/infdis/jiad069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 02/22/2023] [Accepted: 03/21/2023] [Indexed: 03/24/2023] Open
Abstract
BACKGROUND Acinetobacter baumannii causes a wide range of dangerous infections due to the emergence of pandrug-resistant strains. Therefore, there is a need for alternative therapeutics to treat these infections, including those targeting the host immune responses. However, immune responses, especially the humoral response against this pathogen, are poorly understood. METHODS This study investigated the lymphocyte-mediated innate immune resistance to A. baumannii AB5075 pulmonary infection using B- and T-cell-deficient (Rag2-/-) mice, the protective effect of natural antibodies (NAbs), and the expression of complement-mediated responses using a mouse pneumonia model. RESULTS Our results showed that intranasally infected Rag2-/- mice are impaired in clearing bacteria from lung, liver, and spleen at 24 hours postinfection compared to wildtype mice. Animal pretreatment with normal mouse serum or purified antibodies from naive mice rescued Rag2-/- mice from infection. Analysis of C3 complement protein binding demonstrated that NAbs increased C3 protein deposition on A. baumannii cells, indicating the activation of the classical complement pathway by NAbs. CONCLUSIONS Overall, our study shows that NAbs mediate innate immune resistance against A. baumannii, a finding that may lead to the development of effective therapies against human infections caused by this antibiotic-resistant A. baumannii.
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Mezcord V, Escalante J, Nishimura B, Traglia GM, Sharma R, Vallé Q, Tuttobene MR, Subils T, Marin I, Pasteran F, Actis LA, Tolmasky ME, Bonomo RA, Rao G, Ramirez MS. Induced Heteroresistance in Carbapenem-Resistant Acinetobacter baumannii (CRAB) via Exposure to Human Pleural Fluid (HPF) and Its Impact on Cefiderocol Susceptibility. Int J Mol Sci 2023; 24:11752. [PMID: 37511511 PMCID: PMC10380697 DOI: 10.3390/ijms241411752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 07/18/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
Infections caused by Carbapenem-resistant Acinetobacter baumannii (CRAB) isolates, such as hospital-acquired pneumonia (HAP), bacteremia, and skin and soft tissue infections, among others, are particularly challenging to treat. Cefiderocol, a chlorocatechol-substituted siderophore antibiotic, was approved by the U.S. Food and Drug Administration (FDA) in 2019 and prescribed for the treatment of CRAB infections. Despite the initial positive treatment outcomes with this antimicrobial, recent studies reported a higher-than-average all-cause mortality rate in patients treated with cefiderocol compared to the best available therapy. The cause(s) behind these outcomes remains unconfirmed. A plausible hypothesis is heteroresistance, a phenotype characterized by the survival of a small proportion of cells in a population that is seemingly isogenic. Recent results have demonstrated that the addition of human fluids to CRAB cultures leads to cefiderocol heteroresistance. Here, we describe the molecular and phenotypic analyses of CRAB heteroresistant bacterial subpopulations to better understand the nature of the less-than-expected successful outcomes after cefiderocol treatment. Isolation of heteroresistant variants of the CRAB strain AMA40 was carried out in cultures supplemented with cefiderocol and human pleural fluid (HPF). Two AMA40 variants, AMA40 IHC1 and IHC2, were resistant to cefiderocol. To identify mutations and gene expression changes associated with cefiderocol heteroresistance, we subjected these variants to whole genome sequencing and global transcriptional analysis. We then assessed the impact of these mutations on the pharmacodynamic activity of cefiderocol via susceptibility testing, EDTA and boronic acid inhibition analysis, biofilm formation, and static time-kill assays. Heteroresistant variants AMA40 IHC1 and AMA40 IHC2 have 53 chromosomal mutations, of which 40 are common to both strains. None of the mutations occurred in genes associated with high affinity iron-uptake systems or β-lactam resistance. However, transcriptional analyses demonstrated significant modifications in levels of expression of genes associated with iron-uptake systems or β-lactam resistance. The blaNDM-1 and blaADC-2, as well as various iron-uptake system genes, were expressed at higher levels than the parental strain. On the other hand, the carO and ompA genes' expression was reduced. One of the mutations common to both heteroresistant strains was mapped within ppiA, a gene associated with iron homeostasis in other species. Static time-kill assays demonstrated that supplementing cation-adjusted Mueller-Hinton broth with human serum albumin (HAS), the main protein component of HPF, considerably reduced cefiderocol killing activity for all three strains tested. Notably, collateral resistance to amikacin was observed in both variants. We conclude that exposing CRAB to fluids with high HSA concentrations facilitates the rise of heteroresistance associated with point mutations and transcriptional upregulation of genes coding for β-lactamases and biofilm formation. The findings from this study hold significant implications for understanding the emergence of CRAB resistance mechanisms against cefiderocol treatment. This understanding is vital for the development of treatment guidelines that can effectively address the challenges posed by CRAB infections.
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Affiliation(s)
- Vyanka Mezcord
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (V.M.)
| | - Jenny Escalante
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (V.M.)
| | - Brent Nishimura
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (V.M.)
| | - German M. Traglia
- Unidad de Genómica y Bioinformática, Departamento de Ciencias Biológicas, CENUR Litoral Norte, Universidad de la República, Salto 50000, Uruguay
| | - Rajnikant Sharma
- UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA (Q.V.)
| | - Quentin Vallé
- UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA (Q.V.)
| | - Marisel R. Tuttobene
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario 2000, Argentina
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario 2000, Argentina
| | - Tomás Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario 2000, Argentina
| | - Ingrid Marin
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (V.M.)
| | - Fernando Pasteran
- National Regional Reference Laboratory for Antimicrobial Resistance (NRL), Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, ANLIS Dr. Carlos G. Malbrán, Buenos Aires 1282, Argentina
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (V.M.)
| | - Robert A. Bonomo
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH 44106, USA
| | - Gauri Rao
- UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA (Q.V.)
| | - María S. Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (V.M.)
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Escalante J, Nishimura B, Tuttobene MR, Subils T, Mezcord V, Actis LA, Tolmasky ME, Bonomo RA, Ramirez MS. The Iron Content of Human Serum Albumin Modulates the Susceptibility of Acinetobacter baumannii to Cefiderocol. Biomedicines 2023; 11:639. [PMID: 36831178 PMCID: PMC9953112 DOI: 10.3390/biomedicines11020639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/15/2023] [Accepted: 02/10/2023] [Indexed: 02/22/2023] Open
Abstract
The mortality rates of patients infected with Acinetobacter baumannii who were treated with cefiderocol (CFDC) were not as favorable as those receiving the best available treatment for pulmonary and bloodstream infections. Previous studies showed that the presence of human serum albumin (HSA) or HSA-containing fluids, such as human serum (HS) or human pleural fluid (HPF), in the growth medium is correlated with a decrease in the expression of genes associated with high-affinity siderophore-mediated iron uptake systems. These observations may explain the complexities of the observed clinical performance of CFDC in pulmonary and bloodstream infections, because ferric siderophore transporters enhance the penetration of CFDC into the bacterial cell. The removal of HSA from HS or HPF resulted in a reduction in the minimal inhibitory concentration (MIC) of CFDC. Concomitant with these results, an enhancement in the expression of TonB-dependent transporters known to play a crucial role in transporting iron was observed. In addition to inducing modifications in iron-uptake gene expression, the removal of HSA also decreased the expression of β-lactamases genes. Taken together, these observations suggest that environmental HSA has a role in the expression levels of select A. baumannii genes. Furthermore, the removal of iron from HSA had the same effect as the removal of HSA upon the expression of genes associated with iron uptake systems, also suggesting that at least one of the mechanisms by which HSA regulates the expression of certain genes is through acting as an iron source.
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Affiliation(s)
- Jenny Escalante
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
| | - Brent Nishimura
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
| | - Marisel R. Tuttobene
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario S2000, Argentina
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario S2000, Argentina
| | - Tomás Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario S2000, Argentina
| | - Vyanka Mezcord
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
| | - Robert A. Bonomo
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Research Service and GRECC, Cleveland, OH 44106, USA
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH 44106, USA
| | - María Soledad Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA
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Nishimura B, Escalante J, Tuttobene MR, Subils T, Mezcord V, Pimentel C, Georgeos N, Pasteran F, Rodriguez C, Sieira R, Actis LA, Tolmasky ME, Bonomo RA, Ramirez MS. Acinetobacter baumannii response to cefiderocol challenge in human urine. Sci Rep 2022; 12:8763. [PMID: 35610334 PMCID: PMC9128776 DOI: 10.1038/s41598-022-12829-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 05/17/2022] [Indexed: 11/10/2022] Open
Abstract
Cefiderocol (CFDC) is a novel chlorocatechol-substituted siderophore antibiotic approved to treat complicated urinary tract infections (cUTI) and hospital-acquired and ventilator-acquired pneumonia (HAP/VAP). Previous work determined that albumin-rich human fluids increase the minimum inhibitory concentration (MICs) of Acinetobacter baumannii against CFDC and reduce the expression of genes related to iron uptake systems. This latter effect may contribute to the need for higher concentrations of CFDC to inhibit growth. The presence of human urine (HU), which contains low albumin concentrations, did not modify MIC values of two carbapenem-resistant A. baumannii. Levels of resistance to CFDC were not modified by HU in strain AMA40 but were reduced in strain AB5075. Expanding the studies to other carbapenem-resistant A. baumannii isolates showed that the presence of HU resulted in unmodified or reduced MIC of CDFC values. The expression of piuA, pirA, bauA, and bfnH determined by qRT-PCR was enhanced in A. baumannii AMA40 and AB5075 by the presence of HU in the culture medium. All four tested genes code for functions related to recognition and transport of ferric-siderophore complexes. The effect of HU on expression of pbp1, pbp3, blaOXA-51-like, blaADC, and blaNDM-1, genes associated with resistance to β-lactams, as well as genes coding for efflux pumps and porins was variable, showing dependence with the strain analyzed. We conclude that the lack of significant concentrations of albumin and free iron in HU makes this fluid behave differently from others we tested. Unlike other albumin rich fluids, the presence of HU does not impact the antibacterial activity of CFDC when tested against A. baumannii.
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Affiliation(s)
- Brent Nishimura
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, 800 N State College Blvd, Fullerton, CA, 92831, USA
| | - Jenny Escalante
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, 800 N State College Blvd, Fullerton, CA, 92831, USA
| | - Marisel R Tuttobene
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario, Argentina
| | - Tomás Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario, Argentina
| | - Vyanka Mezcord
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, 800 N State College Blvd, Fullerton, CA, 92831, USA
| | - Camila Pimentel
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, 800 N State College Blvd, Fullerton, CA, 92831, USA
| | - Nardin Georgeos
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, 800 N State College Blvd, Fullerton, CA, 92831, USA
| | - Fernando Pasteran
- National Regional Reference Laboratory for Antimicrobial Resistance (NRL), Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, ANLIS Dr. Carlos G. Malbrán, Buenos Aires, Argentina
| | - Cecilia Rodriguez
- Centro de Referencia Para Lactobacilos (CERELA), CONICET, Tucumán, Argentina
| | | | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, USA
| | - Marcelo E Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, 800 N State College Blvd, Fullerton, CA, 92831, USA
| | - Robert A Bonomo
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH, USA
| | - María Soledad Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, 800 N State College Blvd, Fullerton, CA, 92831, USA.
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Squire MS, Townsend HA, Actis LA. The Influence of Blue Light and the BlsA Photoreceptor on the Oxidative Stress Resistance Mechanisms of Acinetobacter baumannii. Front Cell Infect Microbiol 2022; 12:856953. [PMID: 35402311 PMCID: PMC8987720 DOI: 10.3389/fcimb.2022.856953] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/25/2022] [Indexed: 11/13/2022] Open
Abstract
Acinetobacter baumannii is a catalase-positive Gram-negative bacterial pathogen that causes severe infections among compromised patients. Among its noteworthy regulatory mechanisms, this microorganism regulates its lifestyle through the blue light using flavin (BLUF) protein BlsA. This protein regulates a diverse set of cellular processes that include, but are not limited to, motility, biofilm formation, phenylacetic acid metabolism, iron uptake, and catalase activity. We set out to determine how A. baumannii regulates catalase activity and other related oxidative stress phenotypes in response to light. Notably, because A. baumannii ATCC 17978 encodes four catalase homologs – which we refer to as KatA, KatE, KatE2, and KatG – we also aimed to show which of these enzymes exhibit light- and BlsA-dependent activity. Our work not only provides insight into the general function of all four catalase homologs and the impact of light on these functions, but also directly identifies KatE as a BlsA-regulated enzyme. We further demonstrate that the regulation of KatE by BlsA is dependent on a lysine residue that we previously demonstrated to be necessary for the regulation of surface motility. Furthermore, we show that BlsA’s five most-C-terminal residues – previously considered dispensable for BlsA’s overall function – are necessary for the light-independent and light-dependent regulation of catalase and superoxide dismutase activities, respectively. We hypothesize that these identified critical residues are necessary for BlsA’s interaction with protein partners including the transcriptional regulators Fur and BfmR. Together these data expand the understanding regarding how A. baumannii uses light as a signal to control oxidative stress resistance mechanisms that are critical for its pathophysiology.
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Le C, Pimentel C, Pasteran F, Tuttobene MR, Subils T, Escalante J, Nishimura B, Arriaga S, Carranza A, Mezcord V, Vila AJ, Corso A, Actis LA, Tolmasky ME, Bonomo RA, Ramírez MS. Human Serum Proteins and Susceptibility of Acinetobacter baumannii to Cefiderocol: Role of Iron Transport. Biomedicines 2022; 10:biomedicines10030600. [PMID: 35327400 PMCID: PMC8945497 DOI: 10.3390/biomedicines10030600] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 02/25/2022] [Accepted: 03/01/2022] [Indexed: 01/10/2023] Open
Abstract
Cefiderocol, a recently introduced antibiotic, has a chemical structure that includes a cephalosporin that targets cell wall synthesis and a chlorocatechol siderophore moiety that facilitates cell penetration by active iron transporters. Analysis of the effect that human serum, human serum albumin, and human pleural fluid had on growing Acinetobacter baumannii showed that genes related to iron uptake were down-regulated. At the same time, β-lactamase genes were expressed at higher levels. The minimum inhibitory concentrations of this antimicrobial in A. baumannii cells growing in the presence of human serum, human serum albumin, or human pleural fluid were higher than those measured when these fluids were absent from the culture medium. These results correlate with increased expression levels of β-lactamase genes and the down-regulation of iron uptake-related genes in cultures containing human serum, human serum albumin, or human pleural fluid. These modifications in gene expression could explain the less-than-ideal clinical response observed in patients with pulmonary or bloodstream A. baumannii infections. The exposure of the infecting cells to the host’s fluids could cause reduced cefiderocol transport capabilities and increased resistance to β-lactams. The regulation of genes that could impact the A. baumannii susceptibility to cefiderocol, or other antibacterials, is an understudied phenomenon that merits further investigation.
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Affiliation(s)
- Casin Le
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
| | - Camila Pimentel
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
| | - Fernando Pasteran
- National/Regional Reference Laboratory for Antimicrobial Resistance (NRL), Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, ANLIS Dr. Carlos G. Malbrán, Buenos Aires C1282, Argentina; (F.P.); (A.C.)
| | - Marisel R. Tuttobene
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario S2000, Argentina;
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario S2000, Argentina;
| | - Tomás Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario S2002, Argentina;
| | - Jenny Escalante
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
| | - Brent Nishimura
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
| | - Susana Arriaga
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
| | - Aimee Carranza
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
| | - Vyanka Mezcord
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
| | - Alejandro J. Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario S2000, Argentina;
- Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario S2000, Argentina
| | - Alejandra Corso
- National/Regional Reference Laboratory for Antimicrobial Resistance (NRL), Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, ANLIS Dr. Carlos G. Malbrán, Buenos Aires C1282, Argentina; (F.P.); (A.C.)
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, OH 45056, USA;
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
| | - Robert A. Bonomo
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH 44106, USA
- Correspondence: (R.A.B.); (M.S.R.); Tel.: +1-216-791-3800 (R.A.B.); Tel.: +1-657-278-4562 (M.S.R.)
| | - Maria Soledad Ramírez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831, USA; (C.L.); (C.P.); (J.E.); (B.N.); (S.A.); (A.C.); (V.M.); (M.E.T.)
- Correspondence: (R.A.B.); (M.S.R.); Tel.: +1-216-791-3800 (R.A.B.); Tel.: +1-657-278-4562 (M.S.R.)
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8
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Kumar A, Yang T, Chakravorty S, Majumdar A, Nairn BL, Six DA, Marcondes Dos Santos N, Price SL, Lawrenz MB, Actis LA, Marques M, Russo TA, Newton SM, Klebba PE. Fluorescent sensors of siderophores produced by bacterial pathogens. J Biol Chem 2022; 298:101651. [PMID: 35101443 PMCID: PMC8921320 DOI: 10.1016/j.jbc.2022.101651] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/25/2022] Open
Abstract
Siderophores are iron-chelating molecules that solubilize Fe3+ for microbial utilization and facilitate colonization or infection of eukaryotes by liberating host iron for bacterial uptake. By fluorescently labeling membrane receptors and binding proteins, we created 20 sensors that detect, discriminate, and quantify apo- and ferric siderophores. The sensor proteins originated from TonB-dependent ligand-gated porins (LGPs) of Escherichia coli (Fiu, FepA, Cir, FhuA, IutA, BtuB), Klebsiella pneumoniae (IroN, FepA, FyuA), Acinetobacter baumannii (PiuA, FepA, PirA, BauA), Pseudomonas aeruginosa (FepA, FpvA), and Caulobacter crescentus (HutA) from a periplasmic E. coli binding protein (FepB) and from a human serum binding protein (siderocalin). They detected ferric catecholates (enterobactin, degraded enterobactin, glucosylated enterobactin, dihydroxybenzoate, dihydroxybenzoyl serine, cefidericol, MB-1), ferric hydroxamates (ferrichromes, aerobactin), mixed iron complexes (yersiniabactin, acinetobactin, pyoverdine), and porphyrins (hemin, vitamin B12). The sensors defined the specificities and corresponding affinities of the LGPs and binding proteins and monitored ferric siderophore and porphyrin transport by microbial pathogens. We also quantified, for the first time, broad recognition of diverse ferric complexes by some LGPs, as well as monospecificity for a single metal chelate by others. In addition to their primary ferric siderophore ligands, most LGPs bound the corresponding aposiderophore with ∼100-fold lower affinity. These sensors provide insights into ferric siderophore biosynthesis and uptake pathways in free-living, commensal, and pathogenic Gram-negative bacteria.
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Affiliation(s)
- Ashish Kumar
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Taihao Yang
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Somnath Chakravorty
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA; Department of Medicine, Jacobs School of Medicine & Biomedical Sciences, University of Buffalo School of Medicine, Buffalo, New York, USA
| | - Aritri Majumdar
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Brittany L Nairn
- Department of Biological Sciences, Bethel University, St. Paul, Minnesota, USA
| | - David A Six
- Department of Biology, Venatorx Pharmaceuticals, Inc, Malvern, Pennsylvania, USA
| | - Naara Marcondes Dos Santos
- Departamento de Microbiologia, Instituto de Ciencias Biomedicas, Universidade de São Paulo, São Paulo, Brazil
| | - Sarah L Price
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Matthew B Lawrenz
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, Ohio, USA
| | - Marilis Marques
- Departamento de Microbiologia, Instituto de Ciencias Biomedicas, Universidade de São Paulo, São Paulo, Brazil
| | - Thomas A Russo
- Department of Medicine, Jacobs School of Medicine & Biomedical Sciences, University of Buffalo School of Medicine, Buffalo, New York, USA
| | - Salete M Newton
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Phillip E Klebba
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA.
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9
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Rainey A, Pierce A, Deng X, Actis LA, Smith P, Kiss AJ, Wilson TJ. Validation and deployment of a direct saliva real-time RT-PCR test on pooled samples for COVID-19 surveillance testing. PLoS One 2021; 16:e0261956. [PMID: 34969053 PMCID: PMC8718011 DOI: 10.1371/journal.pone.0261956] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 12/15/2021] [Indexed: 02/07/2023] Open
Abstract
A direct, real-time reverse transcriptase PCR test on pooled saliva was validated in 2,786 participants against oropharyngeal swabs. Among asymptomatic/pre-symptomatic participants, the test was found to be in 99.21% agreement and 45% more sensitive than contemporaneous oropharyngeal swabs. The test was then used for surveillance testing on 44,242 saliva samples from asymptomatic participants. Those whose saliva showed evidence of SARS-CoV-2 within 50 cycles of amplification were referred for confirmatory testing, with 87% of those tested by nasal swab within 72 hours receiving a positive diagnostic result on Abbott ID NOW or real-time PCR platforms. Median Ct values on the saliva PCR for those with a positive and negative confirmatory tests was 30.67 and 35.92 respectively, however, binary logistic regression analysis of the saliva Ct values indicates that Ct thresholds as high as 47 may be useful in a surveillance setting. Overall, data indicate that direct RT-PCR testing of pooled saliva samples is an effective method of SARS-CoV-2 surveillance.
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Affiliation(s)
- Amanda Rainey
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Austin Pierce
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Xiaoyun Deng
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Philip Smith
- Department of Kinesiology, Nutrition, and Health, Miami University, Oxford, Ohio, United States of America
| | - Andor J. Kiss
- Center for Bioinformatics and Functional Genomics, Miami University, Oxford, Ohio, United States of America
| | - Timothy J. Wilson
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
- * E-mail:
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10
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Le C, Pimentel C, Tuttobene MR, Subils T, Papp-Wallace KM, Bonomo RA, Actis LA, Tolmasky ME, Ramirez MS. Effect of Serum Albumin, a Component of Human Pleural Fluid, on Transcriptional and Phenotypic Changes on Acinetobacter baumannii A118. Curr Microbiol 2021; 78:3829-3834. [PMID: 34522980 PMCID: PMC8557393 DOI: 10.1007/s00284-021-02649-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/27/2021] [Indexed: 11/25/2022]
Abstract
Acinetobacter baumannii is a multidrug-resistant pathogen that causes numerous infections associated with high mortality rates. Exposure to human body fluids, such as human pleural fluid (HPF) and human serum, modulates gene expression in A. baumannii, leading to changes in its pathogenic behavior. Diverse degrees of effects at the transcriptional level were observed in susceptible and carbapenem-resistant strains. The transcriptional analysis of AB5075, a hyper-virulent and extensively drug-resistant strain showed changes in genes associated with quorum sensing, quorum quenching, fatty acids metabolism, and high-efficient iron uptake systems. In addition, the distinctive role of human serum albumin (HSA) as a critical component of HPF was evidenced. In the present work, we used model strain to analyze more deeply into the contribution of HSA in triggering A. baumannii's response. By qRT-PCR analysis, changes in the expression level of genes associated with quorum sensing, biofilm formation, and phenylacetic acid pathway were observed. Phenotypic approaches confirmed the transcriptional response. HSA, a predominant component of HPF, can modulate the expression and behavior of genes not only in a hyper-virulent and extensively drug-resistant A. baumannii model, but also in other strains with a different degree of susceptibility and pathogenicity.
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Affiliation(s)
- Casin Le
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Camila Pimentel
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Marisel R Tuttobene
- Área Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Tomas Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario, Argentina
| | - Krisztina M Papp-Wallace
- Research Service, Veterans Affairs Northeast Ohio Healthcare System, Cleveland, OH, USA
- Departments of Medicine, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH, USA
| | - Robert A Bonomo
- Research Service, Veterans Affairs Northeast Ohio Healthcare System, Cleveland, OH, USA
- Departments of Medicine, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH, USA
- GRECC, Veterans Affairs Northeast Ohio Healthcare System, Cleveland, OH, USA
- Departments of Pharmacology, Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH, 45056, USA
| | - Marcelo E Tolmasky
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Maria Soledad Ramirez
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA.
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11
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Pimentel C, Le C, Tuttobene MR, Subils T, Martinez J, Sieira R, Papp-Wallace KM, Keppetipola N, Bonomo RA, Actis LA, Tolmasky ME, Ramirez MS. Human Pleural Fluid and Human Serum Albumin Modulate the Behavior of a Hypervirulent and Multidrug-Resistant (MDR) Acinetobacter baumannii Representative Strain. Pathogens 2021; 10:pathogens10040471. [PMID: 33924559 PMCID: PMC8069197 DOI: 10.3390/pathogens10040471] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/09/2021] [Accepted: 04/11/2021] [Indexed: 02/07/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen capable of causing serious infections associated with high rates of morbidity and mortality. Due to its antimicrobial drug resistance profile, A. baumannii is categorized as an urgent priority pathogen by the Centers for Disease Control and Prevention in the United States and a priority group 1 critical microorganism by the World Health Organization. Understanding how A. baumannii adapts to different host environments may provide critical insights into strategically targeting this pathogen with novel antimicrobial and biological therapeutics. Exposure to human fluids was previously shown to alter the gene expression profile of a highly drug-susceptible A. baumannii strain A118 leading to persistence and survival of this pathogen. Herein, we explore the impact of human pleural fluid (HPF) and human serum albumin (HSA) on the gene expression profile of a highly multi-drug-resistant strain of A. baumannii AB5075. Differential expression was observed for ~30 genes, whose products are involved in quorum sensing, quorum quenching, iron acquisition, fatty acid metabolism, biofilm formation, secretion systems, and type IV pilus formation. Phenotypic and further transcriptomic analysis using quantitative RT-PCR confirmed RNA-seq data and demonstrated a distinctive role of HSA as the molecule involved in A. baumannii’s response.
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Affiliation(s)
- Camila Pimentel
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Casin Le
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Marisel R. Tuttobene
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Tomas Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario S2002LRK, Argentina;
| | - Jasmine Martinez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Rodrigo Sieira
- Fundación Instituto Leloir—IIBBA CONICET, Buenos Aires C1405BWE, Argentina;
| | - Krisztina M. Papp-Wallace
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA; (K.M.P.-W.); (R.A.B.)
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH 44106, USA
| | - Niroshika Keppetipola
- Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, CA 92831-3599, USA;
| | - Robert A. Bonomo
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA; (K.M.P.-W.); (R.A.B.)
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH 44106, USA
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, OH 45056, USA;
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Maria Soledad Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
- Correspondence: ; Tel.: +1-657-278-4562
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12
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Grier JT, Arivett BA, Ramírez MS, Chosed RJ, Bigner JA, Ohneck EJ, Metz ML, Wood CR, Arce S, Tartaro A, Relich RF, Actis LA, Fiester SE. Two Acinetobacter baumannii Isolates Obtained From a Fatal Necrotizing Fasciitis Infection Display Distinct Genomic and Phenotypic Characteristics in Comparison to Type Strains. Front Cell Infect Microbiol 2021; 11:635673. [PMID: 33912474 PMCID: PMC8072282 DOI: 10.3389/fcimb.2021.635673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/11/2021] [Indexed: 11/23/2022] Open
Abstract
Acinetobacter baumannii has been recognized as a critical pathogen that causes severe infections worldwide not only because of the emergence of extensively drug-resistant (XDR) derivatives, but also because of its ability to persist in medical environments and colonize compromised patients. While there are numerous reports describing the mechanisms by which this pathogen acquires resistance genes, little is known regarding A. baumannii’s virulence functions associated with rare manifestations of infection such as necrotizing fasciitis, making the determination and implementation of alternative therapeutic targets problematic. To address this knowledge gap, this report describes the analysis of the NFAb-1 and NFAb-2 XDR isolates, which were obtained at two time points during a fatal case of necrotizing fasciitis, at the genomic and functional levels. The comparative genomic analysis of these isolates with the ATCC 19606T and ATCC 17978 strains showed that the NFAb-1 and NFAb-2 isolates are genetically different from each other as well as different from the ATCC 19606T and ATCC 17978 clinical isolates. These genomic differences could be reflected in phenotypic differences observed in these NFAb isolates. Biofilm, cell viability and flow cytometry assays indicate that all tested strains caused significant decreases in A549 human alveolar epithelial cell viability with ATCC 17978, NFAb-1 and NFAb-2 producing significantly less biofilm and significantly more hemolysis and capacity for intracellular invasion than ATCC 19606T. NFAb-1 and NFAb-2 also demonstrated negligible surface motility but significant twitching motility compared to ATCC 19606T and ATCC 17978, likely due to the presence of pili exceeding 2 µm in length, which are significantly longer and different from those previously described in the ATCC 19606T and ATCC 17978 strains. Interestingly, infection with cells of the NFAb-1 isolate, which were obtained from a premortem blood sample, lead to significantly higher mortality rates than NFAb-2 bacteria, which were obtained from postmortem tissue samples, when tested using the Galleria mellonella in vivo infection model. These observations suggest potential changes in the virulence phenotype of the A. baumannii necrotizing fasciitis isolates over the course of infection by mechanisms and cell processes that remain to be identified.
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Affiliation(s)
- Jennifer T Grier
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States
| | - Brock A Arivett
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, United States
| | - Maria S Ramírez
- Department of Biological Science, California State University Fullerton, Fullerton, CA, United States
| | - Renee J Chosed
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States
| | - Jessica A Bigner
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States
| | - Emily J Ohneck
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Maeva L Metz
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Cecily R Wood
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Sergio Arce
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States.,Cancer Institute, Prisma Health, Greenville, SC, United States
| | - Andrea Tartaro
- Computer Science Department, Furman University, Greenville, SC, United States
| | - Ryan F Relich
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Steven E Fiester
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States.,Department of Pathology, Prisma Health, Greenville, SC, United States
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13
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Bogue AL, Panmanee W, McDaniel CT, Mortensen JE, Kamau E, Actis LA, Johannigman JA, Schurr MJ, Satish L, Kotagiri N, Hassett DJ. AB569, a non-toxic combination of acidified nitrite and EDTA, is effective at killing the notorious Iraq/Afghanistan combat wound pathogens, multi-drug resistant Acinetobacter baumannii and Acinetobacter spp. PLoS One 2021; 16:e0247513. [PMID: 33657146 PMCID: PMC7928478 DOI: 10.1371/journal.pone.0247513] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 02/08/2021] [Indexed: 11/19/2022] Open
Abstract
Multi-drug resistant (MDR) Acinetobacter baumannii (Ab) and Acinetobacter spp. present monumental global health challenges. These organisms represent model Gram-negative pathogens with known antibiotic resistance and biofilm-forming properties. Herein, a novel, nontoxic biocide, AB569, consisting of acidified nitrite (A-NO2-) and ethylenediaminetetraacetic acid (EDTA), demonstrated bactericidal activity against all Ab and Acinetobacter spp. strains, respectively. Average fractional inhibitory concentrations (FICs) of 0.25 mM EDTA plus 4 mM A-NO2- were observed across several clinical reference and multiple combat wound isolates from the Iraq/Afghanistan wars. Importantly, toxicity testing on human dermal fibroblasts (HDFa) revealed an upper toxicity limit of 3 mM EDTA plus 64 mM A-NO2-, and thus are in the therapeutic range for effective Ab and Acinetobacter spp. treatment. Following treatment of Ab strain ATCC 19606 with AB569, quantitative PCR analysis of selected genes products to be responsive to AB569 revealed up-regulation of iron regulated genes involved in siderophore production, siderophore biosynthesis non-ribosomal peptide synthetase module (SBNRPSM), and siderophore biosynthesis protein monooxygenase (SBPM) when compared to untreated organisms. Taken together, treating Ab infections with AB569 at inhibitory concentrations reveals the potential clinical application of preventing Ab from gaining an early growth advantage during infection followed by extensive bactericidal activity upon subsequent exposures.
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Affiliation(s)
- Amy L. Bogue
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
- Wright-Patterson Air Force Base, Dayton (Wright-Patterson Air Force Base), Dayton, OH, United States of America
| | - Warunya Panmanee
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Cameron T. McDaniel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Joel E. Mortensen
- Diagnostic Infectious Disease Testing Laboratory and Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States of America
| | - Edwin Kamau
- Walter Reed National Military Medical Center (WRNMMC), Bethesda, MD, United States of America
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, OH, United States of America
| | - Jay A. Johannigman
- U.S. Army Institute of Surgical Research, San Antonio, TX, United States of America
| | - Michael J. Schurr
- Department of Immunology and Microbiology, University of Colorado Anschutz School of Medicine, Denver, CO, United States of America
| | - Latha Satish
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
- College of Pharmacy, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
| | - Nalinikanth Kotagiri
- Research Department, Shriners Hospitals for Children- Cincinnati, Cincinnati, OH, United States of America
| | - Daniel J. Hassett
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States of America
- * E-mail:
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14
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Wood CR, Squire MS, Finley NL, Page RC, Actis LA. Structural and functional analysis of the Acinetobacter baumannii BlsA photoreceptor and regulatory protein. PLoS One 2019; 14:e0220918. [PMID: 31415622 PMCID: PMC6695109 DOI: 10.1371/journal.pone.0220918] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/25/2019] [Indexed: 12/22/2022] Open
Abstract
The Acinetobacter baumannii BlsA photoreceptor has an N-terminal (NT) BLUF domain and a C-terminal (CT) amino acid sequence with no significant homology to characterized bacterial proteins. In this study, we tested the biological role of specific residues located in these BlsA regions. Site-directed mutagenesis, surface motility assays at 24°C and protein overexpression showed that residues Y7, Q51 and W92 are essential for not only light-regulated motility, but also BlsA's solubility when overexpressed in a heterologous host. In contrast, residues A29 and F32, the latter representing a difference when compared with other BLUF-containing photoreceptors, do not play a major role in BlsA's biological functions. Analysis of the CT region showed that the deletion of the last five BlsA residues has no significant effect on the protein's light-sensing and motility regulatory functions, but the deletion of the last 14 residues as well as K144E and K145E substitutions significantly alter light-regulated motility responses. In contrast to the NT mutants, these CT derivatives were overexpressed and purified to homogeneity to demonstrate that although these mutations do not significantly affect flavin binding and photocycling, they do affect BlsA's photodynamic properties. Notably, these mutations map within a potential fifth α-helical component that could play a role in predicted interactions between regulatory partners and BlsA, which could function as a monomer according to gel filtration data. All these observations indicate that although BlsA shares common structural and functional properties with unrelated photoreceptors, it also exhibits unique features that make it a distinct BLUF photoreceptor.
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Affiliation(s)
- Cecily R. Wood
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Mariah S. Squire
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Natosha L. Finley
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Richard C. Page
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio, United States of America
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
- * E-mail:
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15
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Ramirez MS, Penwell WF, Traglia GM, Zimbler DL, Gaddy JA, Nikolaidis N, Arivett BA, Adams MD, Bonomo RA, Actis LA, Tolmasky ME. Identification of Potential Virulence Factors in the Model Strain Acinetobacter baumannii A118. Front Microbiol 2019; 10:1599. [PMID: 31396168 PMCID: PMC6663985 DOI: 10.3389/fmicb.2019.01599] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 06/26/2019] [Indexed: 11/13/2022] Open
Abstract
Acinetobacter baumannii A118, a strain isolated from the blood of an infected patient, is naturally competent and unlike most clinical strains, is susceptible to a variety of different antibiotics including those usually used for selection in genetic manipulations. These characteristics make strain A118 a convenient model for genetic studies of A. baumannii. To identify potential virulence factors, its complete genome was analyzed and compared to other A. baumannii genomes. A. baumannii A118 includes gene clusters coding for the acinetobactin and baumannoferrin iron acquisition systems. Iron-regulated expression of the BauA outer membrane receptor for ferric-acinetobactin complexes was confirmed as well as the utilization of acinetobactin. A. baumannii A118 also possesses the feoABC genes, which code for the main bacterial ferrous uptake system. The functionality of baumannoferrin was suggested by the ability of A. baumannii A118 culture supernatants to cross feed an indicator BauA-deficient strain plated on iron-limiting media. A. baumannii A118 behaved as non-motile but included the csuA/BABCDE chaperone-usher pilus assembly operon and produced biofilms on polystyrene and glass surfaces. While a known capsular polysaccharide (K) locus was identified, the outer core polysaccharide (OC) locus, which belongs to group B, showed differences with available sequences. Our results show that despite being susceptible to most antibiotics, strain A118 conserves known virulence-related traits enhancing its value as model to study A. baumannii pathogenicity.
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Affiliation(s)
- Maria S Ramirez
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University, Fullerton, Fullerton, CA, United States
| | - William F Penwell
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - German M Traglia
- Laboratorio de Bacteriología Clínica, Departamento de Bioquímica Clínica, Facultad de Farmacia y Bioquímica, Hospital de Clínicas "José de San Martín", Buenos Aires, Argentina
| | - Daniel L Zimbler
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Jennifer A Gaddy
- Department of Microbiology, Miami University, Oxford, OH, United States.,Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Nikolas Nikolaidis
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University, Fullerton, Fullerton, CA, United States
| | - Brock A Arivett
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Mark D Adams
- Department of Genetics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Robert A Bonomo
- Departments of Pharmacology and Molecular Biology and Microbiology, Louis Stokes Cleveland Veterans Affairs Medical Center, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Marcelo E Tolmasky
- Department of Biological Science, Center for Applied Biotechnology Studies, California State University, Fullerton, Fullerton, CA, United States
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16
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Hassan F, Ni S, Becker TL, Kinstedt CM, Abdul-Samad JL, Actis LA, Kennedy MA. Evaluation of the Antibacterial Activity of 75 Mushrooms Collected in the Vicinity of Oxford, Ohio (USA). Int J Med Mushrooms 2019; 21:131-141. [PMID: 30806220 DOI: 10.1615/intjmedmushrooms.2018029710] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Antibiotic-resistant bacteria are an increasing and serious health concern worldwide, and multidrug-resistant pathogens are increasingly emerging among patients across the United States. Researchers are exploring sources of traditional medicines, including mushrooms, to find new antibiotic compounds. In this study, the antibiotic activities of 75 mushrooms collected in the area surrounding Oxford, Ohio (USA), were assayed for antibiotic activity against 6 bacterial strains (Pseudomonas aeruginosa reference strains PAO1 and PA14, P. fluorescens, Bacillus subtilis, Staphylococcus epidermidis, and Micrococcus luteus). Mushroom samples were identified by using DNA ribotyping. We used methanol and water extracts of mushrooms in agar diffusion assays to screen for antibiotic activity toward each bacterial strain. A total of 25 mushroom species had antibacterial activity against at least 1 bacterium. Water extracts of Polyporus squamosus, Ganoderma applanatum, Lentinellus subaustralis, Laetiporus sulphureus, G. lucidum, and Trametes versicolor exhibited strong antibiotic activity against all bacterial strains tested. Water and methanol extracts from 25 mushroom species had significant activity against most of the bacteria tested. A minimum inhibitory concentration (MIC) against S. epidermidis was determined for all samples that exhibited antibiotic activity in the disk assay. The G. lucidum and L. sulphureus extracts displayed the strongest inhibition, with an MIC of 0.1 mg/mL.
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Affiliation(s)
- Faizule Hassan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH
| | - Shuisong Ni
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH
| | - Taylor L Becker
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH
| | | | | | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH
| | - Michael A Kennedy
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH
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17
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Penwell WF, Actis LA. Isolation and Characterization of the Acinetobactin and Baumannoferrin Siderophores Produced by Acinetobacter baumannii. Methods Mol Biol 2019; 1946:259-270. [PMID: 30798562 DOI: 10.1007/978-1-4939-9118-1_24] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Siderophores are high-affinity iron chelators produced and used by bacteria to prosper under iron-limiting conditions they normally encounter in the environment and hosts. In this chapter, we describe the isolation and purification of the siderophores acinetobactin and baumannoferrin produced by the bacterial pathogen Acinetobacter baumannii using XAD-7 batch adsorption and high-pressure liquid chromatography (HPLC). We also describe chemical tests and biological assays used to detect the presence of catechol and hydroxamate siderophores in culture supernatants, XAD-7 extracts, and HPLC fractions.
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Affiliation(s)
- William F Penwell
- Department of Biology and Marine Science, Jacksonville University, Jacksonville, FL, USA.
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH, USA
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18
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Abstract
Acinetobacter baumannii adapts to different environmental conditions by expressing complex regulatory circuitry. Recent studies revealed that this circuitry includes regulatory factors that control the emergence of distinct bacterial subpopulations, which are critical for the capacity of this pathogen to persist in medical settings and cause infections in compromised hosts.
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Affiliation(s)
- Cecily R Wood
- Department of Microbiology, Miami University, Oxford, Ohio, USA
| | - Lydia E Mack
- Department of Microbiology, Miami University, Oxford, Ohio, USA
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, Ohio, USA.
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19
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Draughn GL, Milton ME, Feldmann EA, Bobay BG, Roth BM, Olson AL, Thompson RJ, Actis LA, Davies C, Cavanagh J. The Structure of the Biofilm-controlling Response Regulator BfmR from Acinetobacter baumannii Reveals Details of Its DNA-binding Mechanism. J Mol Biol 2018; 430:806-821. [PMID: 29438671 DOI: 10.1016/j.jmb.2018.02.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 02/02/2018] [Accepted: 02/03/2018] [Indexed: 01/19/2023]
Abstract
The rise of drug-resistant bacterial infections coupled with decreasing antibiotic efficacy poses a significant challenge to global health care. Acinetobacter baumannii is an insidious, emerging bacterial pathogen responsible for severe nosocomial infections aided by its ability to form biofilms. The response regulator BfmR, from the BfmR/S two-component system, is the master regulator of biofilm initiation in A. baumannii and is a tractable therapeutic target. Here we present the structure of A. baumannii BfmR using a hybrid approach combining X-ray crystallography, nuclear magnetic resonance spectroscopy, chemical crosslinking mass spectrometry, and molecular modeling. We also show that BfmR binds the previously proposed bfmRS promoter sequence with moderate affinity. While BfmR shares many traits with other OmpR/PhoB family response regulators, some unusual properties were observed. Most importantly, we observe that when phosphorylated, BfmR binds this promoter sequence with a lower affinity than when not phosphorylated. All other OmpR/PhoB family members studied to date show an increase in DNA-binding affinity upon phosphorylation. Understanding the structural and biochemical mechanisms of BfmR will aid in the development of new antimicrobial therapies.
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Affiliation(s)
- G Logan Draughn
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA; Department of Discovery Sciences, RTI International, 3040 E. Cornwallis Road, Research Triangle Park, NC 27709, USA
| | - Morgan E Milton
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA; Department of Discovery Sciences, RTI International, 3040 E. Cornwallis Road, Research Triangle Park, NC 27709, USA
| | - Erik A Feldmann
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Benjamin G Bobay
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Braden M Roth
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Andrew L Olson
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Richele J Thompson
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
| | - Christopher Davies
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - John Cavanagh
- Department of Discovery Sciences, RTI International, 3040 E. Cornwallis Road, Research Triangle Park, NC 27709, USA.
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20
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Ohneck EJ, Arivett BA, Fiester SE, Wood CR, Metz ML, Simeone GM, Actis LA. Mucin acts as a nutrient source and a signal for the differential expression of genes coding for cellular processes and virulence factors in Acinetobacter baumannii. PLoS One 2018; 13:e0190599. [PMID: 29309434 PMCID: PMC5757984 DOI: 10.1371/journal.pone.0190599] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 12/18/2017] [Indexed: 12/27/2022] Open
Abstract
The capacity of Acinetobacter baumannii to persist and cause infections depends on its interaction with abiotic and biotic surfaces, including those found on medical devices and host mucosal surfaces. However, the extracellular stimuli affecting these interactions are poorly understood. Based on our previous observations, we hypothesized that mucin, a glycoprotein secreted by lung epithelial cells, particularly during respiratory infections, significantly alters A. baumannii's physiology and its interaction with the surrounding environment. Biofilm, virulence and growth assays showed that mucin enhances the interaction of A. baumannii ATCC 19606T with abiotic and biotic surfaces and its cytolytic activity against epithelial cells while serving as a nutrient source. The global effect of mucin on the physiology and virulence of this pathogen is supported by RNA-Seq data showing that its presence in a low nutrient medium results in the differential transcription of 427 predicted protein-coding genes. The reduced expression of ion acquisition genes and the increased transcription of genes coding for energy production together with the detection of mucin degradation indicate that this host glycoprotein is a nutrient source. The increased expression of genes coding for adherence and biofilm biogenesis on abiotic and biotic surfaces, the degradation of phenylacetic acid and the production of an active type VI secretion system further supports the role mucin plays in virulence. Taken together, our observations indicate that A. baumannii recognizes mucin as an environmental signal, which triggers a response cascade that allows this pathogen to acquire critical nutrients and promotes host-pathogen interactions that play a role in the pathogenesis of bacterial infections.
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Affiliation(s)
- Emily J. Ohneck
- Department of Microbiology, Miami University, Oxford, OH, United States of America
| | - Brock A. Arivett
- Department of Microbiology, Miami University, Oxford, OH, United States of America
| | - Steven E. Fiester
- Department of Microbiology, Miami University, Oxford, OH, United States of America
| | - Cecily R. Wood
- Department of Microbiology, Miami University, Oxford, OH, United States of America
| | - Maeva L. Metz
- Department of Microbiology, Miami University, Oxford, OH, United States of America
| | - Gabriella M. Simeone
- Department of Microbiology, Miami University, Oxford, OH, United States of America
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, OH, United States of America
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21
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Álvarez-Fraga L, Rumbo-Feal S, Pérez A, Gómez MJ, Gayoso C, Vallejo JA, Ohneck EJ, Valle J, Actis LA, Beceiro A, Bou G, Poza M. Global assessment of small RNAs reveals a non-coding transcript involved in biofilm formation and attachment in Acinetobacter baumannii ATCC 17978. PLoS One 2017; 12:e0182084. [PMID: 28763494 PMCID: PMC5538643 DOI: 10.1371/journal.pone.0182084] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/12/2017] [Indexed: 12/30/2022] Open
Abstract
Many strains of Acinetobacter baumannii have been described as being able to form biofilm. Small non-coding RNAs (sRNAs) control gene expression in many regulatory circuits in bacteria. The aim of the present work was to provide a global description of the sRNAs produced both by planktonic and biofilm-associated (sessile) cells of A. baumannii ATCC 17978, and to compare the corresponding gene expression profiles to identify sRNAs molecules associated to biofilm formation and virulence. sRNA was extracted from both planktonic and sessile cells and reverse transcribed. cDNA was subjected to 454-pyrosequencing using the GS-FLX Titanium chemistry. The global analysis of the small RNA transcriptome revealed different sRNA expression patterns in planktonic and biofilm associated cells, with some of the transcripts only expressed or repressed in sessile bacteria. A total of 255 sRNAs were detected, with 185 of them differentially expressed in the different types of cells. A total of 9 sRNAs were expressed only in biofilm cells, while the expression of other 21 coding regions were repressed only in biofilm cells. Strikingly, the expression level of the sRNA 13573 was 120 times higher in biofilms than in planktonic cells, an observation that prompted us to further investigate the biological role of this non-coding transcript. Analyses of an isogenic mutant and over-expressing strains revealed that the sRNA 13573 gene is involved in biofilm formation and attachment to A549 human alveolar epithelial cells. The present work serves as a basis for future studies examining the complex regulatory network that regulate biofilm biogenesis and attachment to eukaryotic cells in A. baumannii ATCC 17978.
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Affiliation(s)
- Laura Álvarez-Fraga
- Departamento de Microbiología, Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), A Coruña, Spain
| | - Soraya Rumbo-Feal
- Departamento de Microbiología, Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), A Coruña, Spain
| | - Astrid Pérez
- Departamento de Microbiología, Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), A Coruña, Spain
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Manuel J. Gómez
- Department of Molecular Evolution, Center for Astrobiology, INTA-CSIC, Torrejón de Ardoz, Madrid, Spain
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Carmen Gayoso
- Departamento de Microbiología, Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), A Coruña, Spain
| | - Juan A. Vallejo
- Departamento de Microbiología, Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), A Coruña, Spain
| | - Emily J. Ohneck
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Jaione Valle
- Departamento de Biofilms Microbianos, Instituto de Agrobiotecnología, Navarra, Spain
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Alejandro Beceiro
- Departamento de Microbiología, Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), A Coruña, Spain
| | - Germán Bou
- Departamento de Microbiología, Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), A Coruña, Spain
- * E-mail: (GB); (MP)
| | - Margarita Poza
- Departamento de Microbiología, Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), A Coruña, Spain
- * E-mail: (GB); (MP)
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22
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Rumbo-Feal S, Pérez A, Ramelot TA, Álvarez-Fraga L, Vallejo JA, Beceiro A, Ohneck EJ, Arivett BA, Merino M, Fiester SE, Kennedy MA, Actis LA, Bou G, Poza M. Contribution of the A. baumannii A1S_0114 Gene to the Interaction with Eukaryotic Cells and Virulence. Front Cell Infect Microbiol 2017; 7:108. [PMID: 28421168 PMCID: PMC5376624 DOI: 10.3389/fcimb.2017.00108] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 03/17/2017] [Indexed: 11/29/2022] Open
Abstract
Genetic and functional studies showed that some components of the Acinetobacter baumannii ATCC 17978 A1S_0112-A1S_0119 gene cluster are critical for biofilm biogenesis and surface motility. Recently, our group has shown that the A1S_0114 gene was involved in biofilm formation, a process related with pathogenesis. Confirming our previous results, microscopy images revealed that the ATCC 17978 Δ0114 derivative lacking this gene was unable to form a mature biofilm structure. Therefore, other bacterial phenotypes were analyzed to determine the role of this gene in the pathogenicity of A. baumannii ATCC 17978. The interaction of the ATCC 17978 parental strain and the Δ0114 mutant with A549 human alveolar epithelial cells was quantified revealing that the A1S_0114 gene was necessary for proper attachment to A549 cells. This dependency correlates with the negative effect of the A1S_0114 deletion on the expression of genes coding for surface proteins and pili-assembly systems, which are known to play a role in adhesion. Three different experimental animal models, including vertebrate and invertebrate hosts, confirmed the role of the A1S_0114 gene in virulence. All of the experimental infection assays indicated that the virulence of the ATCC 17978 was significantly reduced when this gene was inactivated. Finally, we discovered that the A1S_0114 gene was involved in the production of a small lipopeptide-like compound herein referred to as acinetin 505 (Ac-505). Ac-505 was isolated from ATCC 17978 spent media and its chemical structure was interpreted by mass spectrometry. Overall, our observations provide novel information on the role of the A1S_0114 gene in A. baumannii's pathobiology and lay the foundation for future work to determine the mechanisms by which Ac-505, or possibly an Ac-505 precursor, could execute critical functions as a secondary metabolite.
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Affiliation(s)
- Soraya Rumbo-Feal
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Astrid Pérez
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain.,Departamento de Microbiología y Parasitología, Universidad de Santiago de CompostelaSantiago de Compostela, Spain.,Department of Microbiology, Miami UniversityOxford, OH, USA
| | - Theresa A Ramelot
- Department of Chemistry and Biochemistry, Miami UniversityOxford, OH, USA
| | - Laura Álvarez-Fraga
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Juan A Vallejo
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Alejandro Beceiro
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Emily J Ohneck
- Department of Microbiology, Miami UniversityOxford, OH, USA
| | | | - María Merino
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | | | - Michael A Kennedy
- Department of Chemistry and Biochemistry, Miami UniversityOxford, OH, USA
| | - Luis A Actis
- Department of Microbiology, Miami UniversityOxford, OH, USA
| | - Germán Bou
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Margarita Poza
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
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23
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Fiester SE, Arivett BA, Schmidt RE, Beckett AC, Ticak T, Carrier MV, Ghosh R, Ohneck EJ, Metz ML, Sellin Jeffries MK, Actis LA. Iron-Regulated Phospholipase C Activity Contributes to the Cytolytic Activity and Virulence of Acinetobacter baumannii. PLoS One 2016; 11:e0167068. [PMID: 27875572 PMCID: PMC5119829 DOI: 10.1371/journal.pone.0167068] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/08/2016] [Indexed: 12/13/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic Gram-negative pathogen that causes a wide range of infections including pneumonia, septicemia, necrotizing fasciitis and severe wound and urinary tract infections. Analysis of A. baumannii representative strains grown in Chelex 100-treated medium for hemolytic activity demonstrated that this pathogen is increasingly hemolytic to sheep, human and horse erythrocytes, which interestingly contain increasing amounts of phosphatidylcholine in their membranes. Bioinformatic, genetic and functional analyses of 19 A. baumannii isolates showed that the genomes of each strain contained two phosphatidylcholine-specific phospholipase C (PC-PLC) genes, which were named plc1 and plc2. Accordingly, all of these strains were significantly hemolytic to horse erythrocytes and their culture supernatants tested positive for PC-PLC activity. Further analyses showed that the transcriptional expression of plc1 and plc2 and the production of phospholipase and thus hemolytic activity increased when bacteria were cultured under iron-chelation as compared to iron-rich conditions. Testing of the A. baumannii ATCC 19606Tplc1::aph-FRT and plc2::aph isogenic insertion derivatives showed that these mutants had a significantly reduced PC-PLC activity as compared to the parental strain, while testing of plc1::ermAM/plc2::aph demonstrated that this double PC-PLC isogenic mutant expressed significantly reduced cytolytic and hemolytic activity. Interestingly, only plc1 was shown to contribute significantly to A. baumannii virulence using the Galleria mellonella infection model. Taken together, our data demonstrate that both PLC1 and PLC2, which have diverged from a common ancestor, play a concerted role in hemolytic and cytolytic activities; although PLC1 seems to play a more critical role in the virulence of A. baumannii when tested in an invertebrate model. These activities would provide access to intracellular iron stores this pathogen could use during growth in the infected host.
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Affiliation(s)
- Steven E. Fiester
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Brock A. Arivett
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Robert E. Schmidt
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Amber C. Beckett
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Tomislav Ticak
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Mary V. Carrier
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Rajarshi Ghosh
- Biology Department, Middle Tennessee State University, Murfreesboro, Tennessee, United States of America
| | - Emily J. Ohneck
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Maeva L. Metz
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | | | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
- * E-mail:
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24
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Pérez A, Merino M, Rumbo-Feal S, Álvarez-Fraga L, Vallejo JA, Beceiro A, Ohneck EJ, Mateos J, Fernández-Puente P, Actis LA, Poza M, Bou G. The FhaB/FhaC two-partner secretion system is involved in adhesion of Acinetobacter baumannii AbH12O-A2 strain. Virulence 2016; 8:959-974. [PMID: 27858524 DOI: 10.1080/21505594.2016.1262313] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Acinetobacter baumannii is a hospital-acquired pathogen that shows an extraordinary capacity to stay in the hospital environment. Adherence of the bacteria to eukaryotic cells or to abiotic surfaces is the first step for establishing an infection. The A. baumannii strain AbH12O-A2 showed an exceptional ability to adhere to A549 epithelial cells. The AbFhaB/FhaC 2-partner secretion (TPS) system involved in adhesion was discovered after the screening of the recently determined A. baumannii AbH12O-A2 strain genome (CP009534.1). The AbFhaB is a large exoprotein which transport to the bacterial surface is mediated by the AbFhaC protein. In the present study, the role of this TPS system in the AbH12O-A2 adherence phenotype was investigated. The functional inactivation of this 2-partner secretion system was addressed by analyzing the outer membrane vesicles (OMV) proteomic profile from the wild-type strain and its derivative mutant AbH12O-A2ΔfhaC demonstrating that AbFhaB is no longer detected in the absence of AbFhaC. Scanning electron microscopy (SEM) and adhesion experiments demonstrated that inactivation of the AbFhaB/FhaC system significantly decreases bacterial attachment to A549 alveolar epithelial cells. Moreover, it has been demonstrated that this 2-partner secretion system is involved in fibronectin-mediated adherence of the A. baumannii AbH12O-A2 isolate. Finally, we report that the AbFhaB/FhaC system is involved in virulence when tested using invertebrate and vertebrate hosts. These data suggest the potential role that this AbFhaB/FhaC secretion system could play in the pathobiology of A. baumannii.
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Affiliation(s)
- A Pérez
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain.,b Departamento de Microbiología y Parasitología , Universidad de Santiago de Compostela (USC) , Santiago de Compostela , Spain.,c Department of Microbiology , Miami University , Oxford , OH , USA
| | - M Merino
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - S Rumbo-Feal
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - L Álvarez-Fraga
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - J A Vallejo
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - A Beceiro
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - E J Ohneck
- c Department of Microbiology , Miami University , Oxford , OH , USA
| | - J Mateos
- d Grupo de Proteómica-ProteoRed/Plataforma PBR2-ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complejo Hospitalario Universitario de A Coruña (CHUAC), Universidade da Coruña (UDC) , A Coruña , Spain.,e Marine Research Institute, Consejo Superior de Investigaciones Científicas (CSIC) , Vigo , Spain
| | - P Fernández-Puente
- d Grupo de Proteómica-ProteoRed/Plataforma PBR2-ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complejo Hospitalario Universitario de A Coruña (CHUAC), Universidade da Coruña (UDC) , A Coruña , Spain
| | - L A Actis
- c Department of Microbiology , Miami University , Oxford , OH , USA
| | - M Poza
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - G Bou
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
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Álvarez-Fraga L, Pérez A, Rumbo-Feal S, Merino M, Vallejo JA, Ohneck EJ, Edelmann RE, Beceiro A, Vázquez-Ucha JC, Valle J, Actis LA, Bou G, Poza M. Analysis of the role of the LH92_11085 gene of a biofilm hyper-producing Acinetobacter baumannii strain on biofilm formation and attachment to eukaryotic cells. Virulence 2016; 7:443-55. [PMID: 26854744 PMCID: PMC4871663 DOI: 10.1080/21505594.2016.1145335] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen that has a considerable ability to survive in the hospital environment partly due to its capacity to form biofilms. The first step in the process of establishing an infection is adherence of the bacteria to target cells. Chaperone-usher pili assembly systems are involved in pilus biogenesis pathways that play an important role in adhesion to host cells and tissues as well as medically relevant surfaces. After screening a collection of strains, a biofilm hyper-producing A. baumannii strain (MAR002) was selected to describe potential targets involved in pathogenicity. MAR002 showed a remarkable ability to form biofilm and attach to A549 human alveolar epithelial cells. Analysis of MAR002 using transmission electron microscopy (TEM) showed a significant presence of pili on the bacterial surface. Putative protein-coding genes involved in pili formation were identified based on the newly sequenced genome of MAR002 strain (JRHB01000001/2 or NZ_JRHB01000001/2). As assessed by qRT-PCR, the gene LH92_11085, belonging to the operon LH92_11070-11085, is overexpressed (ca. 25-fold more) in biofilm-associated cells compared to exponential planktonic cells. In the present work we investigate the role of this gene on the MAR002 biofilm phenotype. Scanning electron microscopy (SEM) and biofilm assays showed that inactivation of LH92_11085 gene significantly reduced bacterial attachment to A549 cells and biofilm formation on plastic, respectively. TEM analysis of the LH92_11085 mutant showed the absence of long pili formations normally present in the wild-type. These observations indicate the potential role this LH92_11085 gene could play in the pathobiology of A baumannii.
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Affiliation(s)
- Laura Álvarez-Fraga
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain
| | - Astrid Pérez
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain.,b Departamento de Microbiología y Parasitología , Universidad de Santiago de Compostela (USC) , Santiago de Compostela , Spain.,c Department of Microbiology , Miami University , Oxford , OH , USA
| | - Soraya Rumbo-Feal
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain
| | - María Merino
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain
| | - Juan Andrés Vallejo
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain
| | - Emily J Ohneck
- c Department of Microbiology , Miami University , Oxford , OH , USA
| | - Richard E Edelmann
- d Center for Advanced Microscopy and Imaging, Miami University , Oxford , OH , USA
| | - Alejandro Beceiro
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain
| | - Juan C Vázquez-Ucha
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain
| | - Jaione Valle
- e Departamento de Biofilms Microbianos , Instituto de Agrobiotecnología , Navarra , Spain
| | - Luis A Actis
- b Departamento de Microbiología y Parasitología , Universidad de Santiago de Compostela (USC) , Santiago de Compostela , Spain.,c Department of Microbiology , Miami University , Oxford , OH , USA
| | - Germán Bou
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain
| | - Margarita Poza
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC) , A Coruña , Spain
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Penwell WF, DeGrace N, Tentarelli S, Gauthier L, Gilbert CM, Arivett BA, Miller AA, Durand-Reville TF, Joubran C, Actis LA. Discovery and Characterization of New Hydroxamate Siderophores, Baumannoferrin A and B, produced by Acinetobacter baumannii. Chembiochem 2015; 16:1896-1904. [PMID: 26235845 DOI: 10.1002/cbic.201500147] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Indexed: 12/14/2022]
Abstract
Acinetobacter baumannii AYE does not produce acinetobactin but grows under iron limitation. Accordingly, analyses of AYE iron-restricted culture supernatants resulted in the isolation of two fractions, which contained only hydroxamates and showed siderophore activity. Structural analyses identified baumannoferrin A and baumannoferrin B, which differ only by a double bond. These siderophores are composed of citrate, 1,3-diaminopropane, 2,4-diaminobutyrate, decenoic acid, and α-ketoglutarate. Analysis of the AYE genome showed the presence of a 12-gene cluster coding for proteins similar to those involved in the production and utilization of the hydroxamate siderophores acinetoferrin and achromobactin. As A. baumannii AYE does not produce acinetobactin and harbors only one gene cluster encoding the production and utilization of a siderophore, this strain's growth under iron limitation depends on baumannoferrin, a novel hydroxamate that could play a role in its virulence.
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Affiliation(s)
- William F Penwell
- Infection Innovative Medicines, AstraZeneca Research and Development, 35 Gatehouse Drive, Waltham, MA 02451 (USA).,Department of Microbiology, Miami University, 500 East High Street, Oxford, OH 45056-1602 (USA)
| | - Nancy DeGrace
- Infection Innovative Medicines, AstraZeneca Research and Development, 35 Gatehouse Drive, Waltham, MA 02451 (USA)
| | - Sharon Tentarelli
- Infection Innovative Medicines, AstraZeneca Research and Development, 35 Gatehouse Drive, Waltham, MA 02451 (USA)
| | - Lise Gauthier
- Waters Corporation, 34 Maple Street, Milford, MA 01757-3604 (USA)
| | - Catherine M Gilbert
- Infection Innovative Medicines, AstraZeneca Research and Development, 35 Gatehouse Drive, Waltham, MA 02451 (USA)
| | - Brock A Arivett
- Department of Microbiology, Miami University, 500 East High Street, Oxford, OH 45056-1602 (USA)
| | - Alita A Miller
- Infection Innovative Medicines, AstraZeneca Research and Development, 35 Gatehouse Drive, Waltham, MA 02451 (USA)
| | - Thomas F Durand-Reville
- Infection Innovative Medicines, AstraZeneca Research and Development, 35 Gatehouse Drive, Waltham, MA 02451 (USA)
| | - Camil Joubran
- Infection Innovative Medicines, AstraZeneca Research and Development, 35 Gatehouse Drive, Waltham, MA 02451 (USA)
| | - Luis A Actis
- Department of Microbiology, Miami University, 500 East High Street, Oxford, OH 45056-1602 (USA)
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Harding CM, Nasr MA, Kinsella RL, Scott NE, Foster LJ, Weber BS, Fiester SE, Actis LA, Tracy EN, Munson RS, Feldman MF. Acinetobacter strains carry two functional oligosaccharyltransferases, one devoted exclusively to type IV pilin, and the other one dedicated to O-glycosylation of multiple proteins. Mol Microbiol 2015; 96:1023-41. [PMID: 25727908 DOI: 10.1111/mmi.12986] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2015] [Indexed: 12/18/2022]
Abstract
Multiple species within the Acinetobacter genus are nosocomial opportunistic pathogens of increasing relevance worldwide. Among the virulence factors utilized by these bacteria are the type IV pili and a protein O-glycosylation system. Glycosylation is mediated by O-oligosaccharyltransferases (O-OTases), enzymes that transfer the glycan from a lipid carrier to target proteins. O-oligosaccharyltransferases are difficult to identify due to similarities with the WaaL ligases that catalyze the last step in lipopolysaccharide synthesis. A bioinformatics analysis revealed the presence of two genes encoding putative O-OTases or WaaL ligases in most of the strains within the genus Acinetobacter. Employing A. nosocomialis M2 and A. baylyi ADP1 as model systems, we show that these genes encode two O-OTases, one devoted uniquely to type IV pilin, and the other one responsible for glycosylation of multiple proteins. With the exception of ADP1, the pilin-specific OTases in Acinetobacter resemble the TfpO/PilO O-OTase from Pseudomonas aeruginosa. In ADP1 instead, the two O-OTases are closely related to PglL, the general O-OTase first discovered in Neisseria. However, one of them is exclusively dedicated to the glycosylation of the pilin-like protein ComP. Our data reveal an intricate and remarkable evolutionary pathway for bacterial O-OTases and provide novel tools for glycoengineering.
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Affiliation(s)
- Christian M Harding
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA.,Department of Pediatrics, College of Medicine, The Ohio State University, Columbus, OH, USA.,Biomedical Sciences Graduate Program, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Mohamed A Nasr
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G2, Canada
| | - Rachel L Kinsella
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G2, Canada
| | - Nichollas E Scott
- Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC, Canada
| | - Leonard J Foster
- Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC, Canada
| | - Brent S Weber
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G2, Canada
| | - Steve E Fiester
- Department of Microbiology, Miami University, Oxford, OH, USA
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH, USA
| | - Erin N Tracy
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Robert S Munson
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Mario F Feldman
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2G2, Canada
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Mussi MA, Actis LA, de Mendoza D, Cybulski LE. Using a microbial physiologic and genetic approach to investigate how bacteria sense physical stimuli. Biochem Mol Biol Educ 2014; 42:427-434. [PMID: 25052184 DOI: 10.1002/bmb.20810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 06/11/2014] [Indexed: 06/03/2023]
Abstract
A laboratory exercise was designed to illustrate how physical stimuli such as temperature and light are sensed and processed by bacteria to elaborate adaptive responses. In particular, we use the well-characterized Des pathway of Bacillus subtilis to show that temperature modulates gene expression, resulting ultimately in modification of the levels of unsaturated fatty acids required to maintain proper membrane fluidity at different temperatures. In addition, we adapt recent findings concerning the modulation by light of traits related to virulence such as motility and biofilm formation in the chemotropic bacterium Acinetobacter baumannii. Beyond the theoretical background that this activity provides regarding sensing of environmental stimuli, the experimental setup includes approaches derived from classic genetics, microbiology, and biochemistry. The incorporation of these kind of teaching and training activities in middle-advanced Microbiology or Bacterial Genetics courses promotes acquisition of general and specific techniques and improves student's comprehension of scientific literature and research.
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Affiliation(s)
- María Alejandra Mussi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI- CONICET), Department of Biological Chemistry, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, 2000, Rosario, Argentina
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Abstract
Acinetobacter baumannii causes a wide range of severe infections among compromised and injured patients worldwide. The relevance of these infections are, in part, due to the ability of this pathogen to sense and react to environmental and host stress signals, allowing it to persist and disseminate in medical settings and the human host. This review summarizes current knowledge on the roles that environmental and cellular stressors play in the ability of A. baumannii to resist nutrient deprivation, oxidative and nitrosative injury, and even the presence of the commonly used antiseptic ethanol, which could serve as a nutrient- and virulence-enhancing signal rather than just being a convenient disinfectant. Emerging experimental evidence supports the role of some of these responses in the pathogenesis of the infections A. baumannii causes in humans and its capacity to resist antibiotics and host response effectors.
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Affiliation(s)
- Steven E Fiester
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
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Golic A, Vaneechoutte M, Nemec A, Viale AM, Actis LA, Mussi MA. Staring at the cold sun: blue light regulation is distributed within the genus Acinetobacter. PLoS One 2013; 8:e55059. [PMID: 23358859 PMCID: PMC3554667 DOI: 10.1371/journal.pone.0055059] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Accepted: 12/23/2012] [Indexed: 11/28/2022] Open
Abstract
We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD)-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1) BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility.
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Affiliation(s)
- Adrián Golic
- Microbiology Division, Instituto de Biología Molecular y Celular de Rosario (IBR- CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Mario Vaneechoutte
- Laboratory for Bacteriology Research, Ghent University Hospital, Ghent University, Ghent, Belgium
| | - Alexandr Nemec
- Laboratory of Bacterial Genetics, National Institute of Public Health, Prague, Czech Republic
| | - Alejandro M. Viale
- Microbiology Division, Instituto de Biología Molecular y Celular de Rosario (IBR- CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - María Alejandra Mussi
- Microbiology Division, Instituto de Biología Molecular y Celular de Rosario (IBR- CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
- * E-mail:
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Naka H, Actis LA, Crosa JH. The anguibactin biosynthesis and transport genes are encoded in the chromosome of Vibrio harveyi: a possible evolutionary origin for the pJM1 plasmid-encoded system of Vibrio anguillarum? Microbiologyopen 2013; 2:182-94. [PMID: 23335587 PMCID: PMC3584223 DOI: 10.1002/mbo3.65] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 11/22/2012] [Accepted: 12/03/2012] [Indexed: 12/31/2022] Open
Abstract
Many Vibrio anguillarum serotype O1 strains carry 65-kb pJM1-type plasmids harboring genes involved in siderophore anguibactin biosynthesis and transport. The anguibactin system is an essential factor for V. anguillarum to survive under iron-limiting conditions, and as a consequence, it is a very important virulence factor of this bacterium. Our comparative analysis of genomic data identified a cluster harboring homologs of anguibactin biosynthesis and transport genes in the chromosome of Vibrio harveyi. We have purified the putative anguibactin siderophore and demonstrated that it is indeed anguibactin by mass spectrometry and specific bioassays. Furthermore, we characterized two genes, angR and fatA, in this chromosome cluster that, respectively, participate in anguibactin biosynthesis and transport as determined by mutagenesis analysis. Furthermore, we found that the V. harveyi FatA protein is located in the outer membrane fractions as previously demonstrated in V. anguillarum. Based on our data, we propose that the anguibactin biosynthesis and transport cluster in the V. anguillarum pJM1 plasmid have likely evolved from the chromosome cluster of V. harveyi or vice versa.
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Affiliation(s)
- Hiroaki Naka
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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Nwugo CC, Arivett BA, Zimbler DL, Gaddy JA, Richards AM, Actis LA. Effect of ethanol on differential protein production and expression of potential virulence functions in the opportunistic pathogen Acinetobacter baumannii. PLoS One 2012; 7:e51936. [PMID: 23284824 PMCID: PMC3527336 DOI: 10.1371/journal.pone.0051936] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 11/09/2012] [Indexed: 12/25/2022] Open
Abstract
Acinetobacter baumannii persists in the medical environment and causes severe human nosocomial infections. Previous studies showed that low-level ethanol exposure increases the virulence of A. baumannii ATCC 17978. To better understand the mechanisms involved in this response, 2-D gel electrophoresis combined with mass spectrometry was used to investigate differential protein production in bacteria cultured in the presence or absence of ethanol. This approach showed that the presence of ethanol significantly induces and represses the production of 22 and 12 proteins, respectively. Although over 25% of the ethanol-induced proteins were stress-response related, the overall bacterial viability was uncompromised when cultured under these conditions. Production of proteins involved in lipid and carbohydrate anabolism was increased in the presence of ethanol, a response that correlates with increased carbohydrate biofilm content, enhanced biofilm formation on abiotic surfaces and decrease bacterial motility on semi-solid surfaces. The presence of ethanol also induced the acidification of bacterial cultures and the production of indole-3-acetic acid (IAA), a ubiquitous plant hormone that signals bacterial stress-tolerance and promotes plant-bacteria interactions. These responses could be responsible for the significantly enhanced virulence of A. baumannii ATCC 17978 cells cultured in the presence of ethanol when tested with the Galleria mellonella experimental infection model. Taken together, these observations provide new insights into the effect of ethanol in bacterial virulence. This alcohol predisposes the human host to infections by A. baumannii and could favor the survival and adaptation of this pathogen to medical settings and adverse host environments.
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Affiliation(s)
- Chika C. Nwugo
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Brock A. Arivett
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Daniel L. Zimbler
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Jennifer A. Gaddy
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Ashley M. Richards
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
- * E-mail:
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Thompson RJ, Bobay BG, Stowe SD, Olson AL, Peng L, Su Z, Actis LA, Melander C, Cavanagh J. Identification of BfmR, a response regulator involved in biofilm development, as a target for a 2-Aminoimidazole-based antibiofilm agent. Biochemistry 2012. [PMID: 23186243 DOI: 10.1021/bi3015289] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
2-Aminoimidazoles (2AIs) have been documented to disrupt bacterial protection mechanisms, including biofilm formation and genetically encoded antibiotic resistance traits. Using Acinetobacter baumannii, we provide initial insight into the mechanism of action of a 2AI-based antibiofilm agent. Confocal microscopy confirmed that the 2AI is cell permeable, while pull-down assays identified BfmR, a response regulator that is the master controller of biofilm formation, as a target for this compound. Binding assays demonstrated specificity of the 2AI for response regulators, while computational docking provided models for 2AI-BfmR interactions. The 2AI compound studied here represents a unique small molecule scaffold that targets bacterial response regulators.
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Affiliation(s)
- Richele J Thompson
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
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Penwell WF, Arivett BA, Actis LA. The Acinetobacter baumannii entA gene located outside the acinetobactin cluster is critical for siderophore production, iron acquisition and virulence. PLoS One 2012; 7:e36493. [PMID: 22570720 PMCID: PMC3343012 DOI: 10.1371/journal.pone.0036493] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Accepted: 04/09/2012] [Indexed: 02/06/2023] Open
Abstract
Acinetobacter baumannii causes severe infections in compromised patients, who present an iron-limited environment that controls bacterial growth. This pathogen has responded to this restriction by expressing high-affinity iron acquisition systems including that mediated by the siderophore acinetobactin. Gene cloning, functional assays and biochemical tests showed that the A. baumannii genome contains a single functional copy of an entA ortholog. This gene, which is essential for the biosynthesis of the acinetobactin precursor 2,3-dihydroxybenzoic acid (DHBA), locates outside of the acinetobactin gene cluster, which otherwise harbors all genes needed for acinetobactin biosynthesis, export and transport. In silico analyses and genetic complementation tests showed that entA locates next to an entB ortholog, which codes for a putative protein that contains the isochorismatase lyase domain, which is needed for DHBA biosynthesis from isochorismic acid, but lacks the aryl carrier protein domain, which is needed for tethering activated DHBA and completion of siderophore biosynthesis. Thus, basF, which locates within the acinetobactin gene cluster, is the only fully functional entB ortholog present in ATCC 19606(T). The differences in amino acid length and sequences between these two EntB orthologs and the differences in the genetic context within which the entA and entB genes are found in different A. baumannii isolates indicate that they were acquired from different sources by horizontal transfer. Interestingly, the AYE strain proved to be a natural entA mutant capable of acquiring iron via an uncharacterized siderophore-mediated system, an observation that underlines the ability of different A. baumannii isolates to acquire iron using different systems. Finally, experimental infections using in vivo and ex vivo models demonstrate the role of DHBA and acinetobactin intermediates in the virulence of the ATCC 19606(T) cells, although to a lesser extent when compared to the responses obtained with bacteria producing and using fully matured acinetobactin to acquire iron.
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Affiliation(s)
- William F. Penwell
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Brock A. Arivett
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
- * E-mail:
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McQueary CN, Actis LA. Acinetobacter baumannii biofilms: variations among strains and correlations with other cell properties. J Microbiol 2011; 49:243-50. [PMID: 21538245 DOI: 10.1007/s12275-011-0343-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 12/20/2010] [Indexed: 11/28/2022]
Abstract
Acinetobacter baumannii is an opportunistic pathogen that causes serious infections in humans by colonizing and persisting on surfaces normally found in hospital settings. The capacity of this pathogen to persist in these settings could be due to its ability to form biofilms on inanimate surfaces. This report shows that although the ATCC 19606(T) type strain and 8 different clinical isolates form biofilms, there are significant variations in the cell density and microscopic structures of these cell aggregates, with 3 of the isolates forming pellicles floating on the surface of stagnant broth cultures. PCR indicated that, like ATCC 19606(T), all 8 clinical isolates harbor all the genetic components of the CsuA/BABCDE chaperone-usher pili assembly system, which is needed for biofilm formation on plastic. Pili detection in cells of all strains examined supports the presence and function of a pilus assembly system. However, only one of them produced the putative ATCC 19606(T) CsuA/B pilin subunit protein. Hydrophobicity tests and motility assays also showed significant variations among all tested strains and did not result in direct correlations between the biofilm phenotype and cell properties that could affect biofilm formation on abiotic surfaces. This lack of correlation among these 3 phenotypes may reflect some of the variations already reported with this pathogen, which may pose a challenge in the treatment of the infections this pathogen causes in humans using biofilm formation on abiotic surfaces as a target.
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Nwugo CC, Gaddy JA, Zimbler DL, Actis LA. Deciphering the iron response in Acinetobacter baumannii: A proteomics approach. J Proteomics 2011; 74:44-58. [PMID: 20692388 DOI: 10.1016/2fj.jprot.2010.07.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 06/22/2010] [Accepted: 07/27/2010] [Indexed: 05/22/2023]
Abstract
Iron is an essential nutrient that plays a role in bacterial differential gene expression and protein production. Accordingly, the comparative analysis of total lysate and outer membrane fractions isolated from A. baumannii ATCC 19606(T) cells cultured under iron-rich and -chelated conditions using 2-D gel electrophoresis-mass spectrometry resulted in the identification of 58 protein spots differentially produced. While 19 and 35 of them represent iron-repressed and iron-induced protein spots, respectively, four other spots represent a metal chelation response unrelated to iron. Most of the iron-repressed protein spots represent outer membrane siderophore receptors, some of which could be involved in the utilization of siderophores produced by other bacteria. The iron-induced protein spots represent a wide range of proteins including those involved in iron storage, such as Bfr, metabolic and energy processes, such as AcnA, AcnB, GlyA, SdhA, and SodB, as well as lipid biosynthesis. The detection of an iron-regulated Hfq ortholog indicates that iron regulation in this bacterium could be mediated by Fur and small RNAs as described in other bacteria. The iron-induced production of OmpA suggests this protein plays a role in iron metabolism as shown by the diminished ability of an isogenic OmpA deficient derivative to grow under iron-chelated conditions.
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Affiliation(s)
- Chika C Nwugo
- Department of Microbiology, Miami University, Oxford, Ohio, USA
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Nwugo CC, Gaddy JA, Zimbler DL, Actis LA. Deciphering the iron response in Acinetobacter baumannii: A proteomics approach. J Proteomics 2010; 74:44-58. [PMID: 20692388 DOI: 10.1016/j.jprot.2010.07.010] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 06/22/2010] [Accepted: 07/27/2010] [Indexed: 12/14/2022]
Abstract
Iron is an essential nutrient that plays a role in bacterial differential gene expression and protein production. Accordingly, the comparative analysis of total lysate and outer membrane fractions isolated from A. baumannii ATCC 19606(T) cells cultured under iron-rich and -chelated conditions using 2-D gel electrophoresis-mass spectrometry resulted in the identification of 58 protein spots differentially produced. While 19 and 35 of them represent iron-repressed and iron-induced protein spots, respectively, four other spots represent a metal chelation response unrelated to iron. Most of the iron-repressed protein spots represent outer membrane siderophore receptors, some of which could be involved in the utilization of siderophores produced by other bacteria. The iron-induced protein spots represent a wide range of proteins including those involved in iron storage, such as Bfr, metabolic and energy processes, such as AcnA, AcnB, GlyA, SdhA, and SodB, as well as lipid biosynthesis. The detection of an iron-regulated Hfq ortholog indicates that iron regulation in this bacterium could be mediated by Fur and small RNAs as described in other bacteria. The iron-induced production of OmpA suggests this protein plays a role in iron metabolism as shown by the diminished ability of an isogenic OmpA deficient derivative to grow under iron-chelated conditions.
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Affiliation(s)
- Chika C Nwugo
- Department of Microbiology, Miami University, Oxford, Ohio, USA
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Abstract
Acinetobacter baumannii is a Gram-negative opportunistic nosocomial pathogen. This microorganism survives in hospital environments despite unfavorable conditions such as desiccation, nutrient starvation and antimicrobial treatments. It is hypothesized that its ability to persist in these environments, as well as its virulence, is a result of its capacity to form biofilms. A. baumannii forms biofilms on abiotic surfaces such as polystyrene and glass as well as biotic surfaces such as epithelial cells and fungal filaments. Pili assembly and production of the Bap surface-adhesion protein play a role in biofilm initiation and maturation after initial attachment to abiotic surfaces. Furthermore, the adhesion and biofilm phenotypes of some clinical isolates seem to be related to the presence of broad-spectrum antibiotic resistance. The regulation of the formation and development of these biofilms is as diverse as the surfaces on which this bacterium persists and as the cellular components that participate in this programmed multistep process. The regulatory processes associated with biofilm formation include sensing of bacterial cell density, the presence of different nutrients and the concentration of free cations available to bacterial cells. Some of these extracellular signals may be sensed by two-component regulatory systems such as BfmRS. This transcriptional regulatory system activates the expression of the usher-chaperone assembly system responsible for the production of pili, needed for cell attachment and biofilm formation on polystyrene surfaces. However, such a system is not required for biofilm formation on abiotic surfaces when cells are cultured in chemically defined media. Interestingly, the BfmRS system also controls cell morphology under particular culture conditions.
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Affiliation(s)
- Jennifer A Gaddy
- Department of Microbiology, Miami University, Oxford, OH 45056, USA.
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Zimbler DL, Penwell WF, Gaddy JA, Menke SM, Tomaras AP, Connerly PL, Actis LA. Iron acquisition functions expressed by the human pathogen Acinetobacter baumannii. Biometals 2009; 22:23-32. [PMID: 19130255 DOI: 10.1007/s10534-008-9202-3] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Accepted: 12/07/2008] [Indexed: 11/26/2022]
Abstract
Acinetobacter baumannii is a gram-negative bacterium that causes serious infections in compromised patients. More recently, it has emerged as the causative agent of severe infections in military personnel wounded in Iraq and Afghanistan. This pathogen grows under a wide range of conditions including iron-limiting conditions imposed by natural and synthetic iron chelators. Initial studies using the type strain 19606 showed that the iron proficiency of this pathogen depends on the expression of the acinetobactin-mediated iron acquisition system. More recently, we have observed that hemin but not human hemoglobin serves as an iron source when 19606 isogenic derivatives affected in acinetobactin transport and biosynthesis were cultured under iron-limiting conditions. This finding is in agreement with the observation that the genome of the strain 17978 has a gene cluster coding for putative hemin-acquisition functions, which include genes coding for putative hemin utilization functions and a TonBExbBD energy transducing system. This system restored enterobactin biosynthesis in an E. coli ExbBD deficient strain but not when introduced into a TonB mutant. PCR and Southern blot analyses showed that this hemin-utilization gene cluster is also present in the 19606 strain. Analysis of the 17978 genome also showed that this strain harbors genes required for acinetobactin synthesis and transport as well as a gene cluster that could code for additional iron acquisition functions. This hypothesis is in agreement with the fact that the inactivation of the basD acinetobactin biosynthetic gene did not affect the growth of A. baumannii 17978 cells under iron-chelated conditions. Interestingly, this second iron uptake gene cluster is flanked by perfect inverted repeats and includes transposase genes that are expressed transcriptionally. Also interesting is the observation that this additional cluster could not be detected in the type strain 19606, an observation that suggests some significant differences in the iron uptake capacity between these two A. baumannii strains. Transposome mutagenesis of the strain 19606 resulted in the isolation of a derivative unable to grow under iron-chelated conditions. Gene mapping and protein analysis together with complementation assays showed that a protein related to SecA, which is a component of the Sec protein secretion system in a wide range of bacteria, is needed at least for the production of the BauA acinetobactin outer membrane receptor. Furthermore, this derivative was unable to use hemin as an iron source under limiting conditions. Taken together, these results indicate that A. baumannii expresses siderophore-mediated and hemin acquisition functions, although different isolates differ in their iron acquisition capacity. Unexpectedly, the ability of this pathogen to acquire iron depends on the expression of a SecA protein secretion function, which has not been associated with iron acquisition in bacteria.
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Affiliation(s)
- Daniel L Zimbler
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
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Tomaras AP, Flagler MJ, Dorsey CW, Gaddy JA, Actis LA. Characterization of a two-component regulatory system from Acinetobacter baumannii that controls biofilm formation and cellular morphology. Microbiology (Reading) 2008; 154:3398-3409. [PMID: 18957593 DOI: 10.1099/mic.0.2008/019471-0] [Citation(s) in RCA: 214] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Acinetobacter baumannii forms biofilms on abiotic surfaces, a phenotype that may explain its ability to survive in nosocomial environments and to cause device-related infections in compromised patients. The biofilm proficiency of the 19606 type strain depends on the production of pili, cell-surface appendages assembled via the CsuAB-A-B-C-D-E chaperone-usher secretion system. The screening of a bank of isogenic insertion derivatives led to the identification of a biofilm-deficient derivative in which a transposon insertion disrupted a gene predicted to encode the response regulator of a two-component regulatory system. This gene, which was named bfmR, is required for the expression of the Csu pili chaperone-usher assembly system. This coding region is followed by an ORF encoding a putative sensor kinase that was named bfmS, which plays a less relevant role in biofilm formation when cells are cultured in rich medium. Further examination showed that the bfmR mutant was capable of attaching to abiotic surfaces, although to levels significantly lower than those of the parental strain, when it was cultured in a chemically defined minimal medium. Additionally, the morphology of planktonic cells of this mutant, when grown in minimal medium, was drastically affected, while adherent mutant cells were indistinguishable in shape and size from the parental strain. Together, these results indicate that BfmR is part of a two-component regulatory system that plays an important role in the morphology of A. baumannii 19606 cells and their ability to form biofilms on abiotic surfaces.
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Affiliation(s)
- Andrew P Tomaras
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
| | | | - Caleb W Dorsey
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
| | - Jennifer A Gaddy
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH 45056, USA
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Soler Bistué AJC, Birshan D, Tomaras AP, Dandekar M, Tran T, Newmark J, Bui D, Gupta N, Hernandez K, Sarno R, Zorreguieta A, Actis LA, Tolmasky ME. Klebsiella pneumoniae multiresistance plasmid pMET1: similarity with the Yersinia pestis plasmid pCRY and integrative conjugative elements. PLoS One 2008; 3:e1800. [PMID: 18350140 PMCID: PMC2262945 DOI: 10.1371/journal.pone.0001800] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 02/15/2008] [Indexed: 11/30/2022] Open
Abstract
Background Dissemination of antimicrobial resistance genes has become an important public health and biodefense threat. Plasmids are important contributors to the rapid acquisition of antibiotic resistance by pathogenic bacteria. Principal Findings The nucleotide sequence of the Klebsiella pneumoniae multiresistance plasmid pMET1 comprises 41,723 bp and includes Tn1331.2, a transposon that carries the blaTEM-1 gene and a perfect duplication of a 3-kbp region including the aac(6′)-Ib, aadA1, and blaOXA-9 genes. The replication region of pMET1 has been identified. Replication is independent of DNA polymerase I, and the replication region is highly related to that of the cryptic Yersinia pestis 91001 plasmid pCRY. The potential partition region has the general organization known as the parFG locus. The self-transmissible pMET1 plasmid includes a type IV secretion system consisting of proteins that make up the mating pair formation complex (Mpf) and the DNA transfer (Dtr) system. The Mpf is highly related to those in the plasmid pCRY, the mobilizable high-pathogenicity island from E. coli ECOR31 (HPIECOR31), which has been proposed to be an integrative conjugative element (ICE) progenitor of high-pathogenicity islands in other Enterobacteriaceae including Yersinia species, and ICEKp1, an ICE found in a K. pneumoniae strain causing primary liver abscess. The Dtr MobB and MobC proteins are highly related to those of pCRY, but the endonuclease is related to that of plasmid pK245 and has no significant homology with the protein of similar function in pCRY. The region upstream of mobB includes the putative oriT and shares 90% identity with the same region in the HPIECOR31. Conclusions The comparative analyses of pMET1 with pCRY, HPIECOR31, and ICEKp1 show a very active rate of genetic exchanges between Enterobacteriaceae including Yersinia species, which represents a high public health and biodefense threat due to transfer of multiple resistance genes to pathogenic Yersinia strains.
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Affiliation(s)
- Alfonso J. C. Soler Bistué
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Daniel Birshan
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Andrew P. Tomaras
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Manisha Dandekar
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Tung Tran
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Jason Newmark
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Duyen Bui
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Nisha Gupta
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Keziah Hernandez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Renee Sarno
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Angeles Zorreguieta
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, Ohio, United States of America
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Science and Mathematics, California State University Fullerton, Fullerton, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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Rodríguez-Baño J, Martí S, Soto S, Fernández-Cuenca F, Cisneros JM, Pachón J, Pascual A, Martínez-Martínez L, McQueary C, Actis LA, Vila J. Biofilm formation in Acinetobacter baumannii: associated features and clinical implications. Clin Microbiol Infect 2008; 14:276-8. [PMID: 18190568 DOI: 10.1111/j.1469-0691.2007.01916.x] [Citation(s) in RCA: 166] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Biofilm formation in 92 unrelated strains of Acinetobacter baumannii isolated in a multicentre cohort study was investigated using a microtitre plate assay. Fifty-six (63%) isolates formed biofilm. These isolates were less frequently resistant to imipenem or ciprofloxacin than were non-biofilm-forming isolates (25% vs. 47%, p 0.04; and 66% vs. 94%, p 0.004, respectively). All catheter-related urinary or bloodstream infections and the sole case of shunt-related meningitis were caused by biofilm-forming strains. Multivariate analysis revealed that treatment in an intensive care unit, ciprofloxacin resistance and isolation from a respiratory sample were associated with non-biofilm-forming isolates, while previous aminoglycoside use was associated with biofilm-forming isolates.
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Affiliation(s)
- J Rodríguez-Baño
- Sección de Enfermedades Infecciosas, Hospital Universitario Virgen Macarena, Sevilla, Spain.
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Rhodes ER, Shoemaker CJ, Menke SM, Edelmann RE, Actis LA. Evaluation of different iron sources and their influence in biofilm formation by the dental pathogen Actinobacillus actinomycetemcomitans. J Med Microbiol 2007; 56:119-128. [PMID: 17172526 DOI: 10.1099/jmm.0.46844-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Actinobacillus actinomycetemcomitans, a pathogen associated with oral and extra-oral infections, requires iron to grow under limiting conditions. Although incapable of producing siderophores, this pathogen could acquire iron by direct interaction with compounds such as haemin, haemoglobin, lactoferrin and transferrin. In this work the ability of different A. actinomycetemcomitans strains to bind and use different iron sources was tested. None of the strains tested used haemoglobin, lactoferrin or transferrin as sole sources of iron. However, all of them used FeCl(3) and haemin as iron sources under chelated conditions. Dot-blot binding assays showed that all strains bind lactoferrin, haemoglobin and haemin, but not transferrin. Insertion inactivation of hmsF, which encodes a predicted cell-envelope protein related to haemin-storage proteins produced by other pathogens, reduced haemin and Congo red binding drastically without affecting haemin utilization as an iron source under chelated conditions. Biofilm assays showed that all strains tested attached to and formed biofilms on plastic under iron-rich and iron-chelated conditions. However, scanning electron microscopy showed that smooth strains formed simpler biofilms than rough isolates. Furthermore, the incubation of rough cells in the presence of FeCl(3) or haemin resulted in the formation of more aggregates and microcolonies compared with the fewer cell aggregates formed when cells were grown in the presence of the synthetic iron chelator dipyridyl. These cell responses to changes in extracellular iron concentrations may reflect those that this pathogen expresses under the conditions it encounters in the human oral cavity.
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Affiliation(s)
- Eric R Rhodes
- Department of Microbiology, Miami University, Oxford, OH, USA
| | | | - Sharon M Menke
- Department of Microbiology, Miami University, Oxford, OH, USA
| | | | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH, USA
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Rhodes ER, Menke S, Shoemaker C, Tomaras AP, McGillivary G, Actis LA. Iron acquisition in the dental pathogen Actinobacillus actinomycetemcomitans: what does it use as a source and how does it get this essential metal? Biometals 2007; 20:365-77. [PMID: 17206384 DOI: 10.1007/s10534-006-9058-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Accepted: 11/28/2006] [Indexed: 11/28/2022]
Abstract
Actinobacillus actinomycetemcomitans requires iron to grow under limiting conditions imposed by synthetic and natural chelators. Although none of the strains tested used hemoglobin, lactoferrin or transferrin, all of them used FeCl3 and hemin as iron sources under chelated conditions. Dot-blot binding assays showed that all strains bind lactoferrin, hemoglobin, and hemin but not transferrin. When compared with smooth strains, the rough isolates showed higher hemin binding activity, which was sensitive to proteinase K treatment. A. actinomycetemcomitans harbors the Fur-regulated afeABCD locus coding for iron acquisition in isogenic and non-isogenic cell backgrounds. The genome of this oral pathogen also harbors several other predicted iron uptake genes including the hitABC locus, which restored iron acquisition in the E. coli 1017 ent mutant. However, the disruption of this locus in the parental strain did not affect iron acquisition as drastically as the inactivation of AfeABCD, suggesting that the latter system could be more involved in iron transport than the HitABC system. The genome of this oral pathogen also harbors an active copy of the exbBexbDtonB operon, which could provide the energy needed for hemin acquisition. However, inactivation of each coding region of this operon did not affect the hemin and iron acquisition phenotypes of isogenic derivatives. This observation suggests that the function of these proteins could be replaced by those coded for by tolQ, tolR and tolA as it was described for other bacterial transport systems. Interruption of a hasR homolog, an actively transcribed gene that is predicted to code for an outer membrane hemophore receptor protein, did not affect the ability of an isogenic derivative to bind and use hemin under chelated conditions. This result also indicates that A. actinomycetemcomitans could produce more than one outer membrane hemin receptor as it was described in other human pathogens. All strains tested formed biofilms on plastic under iron-rich and iron-chelated conditions. However, smooth strains attached poorly and formed weaker biofilms when compared with rough isolates. The incubation of rough cells in the presence of FeCl3 or hemin resulted in an increased number of smaller aggregates and microcolonies as compared to the fewer but larger aggregates formed when cells were grown in the presence of dipyridyl.
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Affiliation(s)
- Eric R Rhodes
- Department of Microbiology, Miami University, 40 Pearson Hall, Oxford, OH 45056, USA
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Dorsey CW, Tomaras AP, Actis LA. Sequence and organization of pMAC, an Acinetobacter baumannii plasmid harboring genes involved in organic peroxide resistance. Plasmid 2006; 56:112-23. [PMID: 16530832 DOI: 10.1016/j.plasmid.2006.01.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/20/2006] [Accepted: 01/21/2006] [Indexed: 11/29/2022]
Abstract
Acinetobacter baumannii 19606 harbors pMAC, a 9540-bp plasmid that contains 11 predicted open-reading frames (ORFs). Cloning and transformation experiments using Acinetobacter calcoaceticus BD413 mapped replication functions within a region containing four 21-bp direct repeats (ori) and ORF 1, which codes for a predicted replication protein. Subcloning and tri-parental mating experiments mapped mobilization functions to the product of ORF 11 and an adjacent predicted oriT. Three ORFs code for proteins that share similarity to hypothetical proteins encoded by plasmid genes found in other bacteria, while the predicted products of three others do not match any known sequence. The product of ORF 8 is similar to Ohr, a hydroperoxide reductase responsible for organic peroxide detoxification and resistance in bacteria. This ORF is immediately upstream of a coding region whose product is related to the MarR family of transcriptional regulators. Disk diffusion assays showed that A. baumannii 19606 is resistant to the organic peroxide-generating compounds cumene hydroperoxide (CHP) and tert-butyl hydroperoxide (t-BHP), although to levels lower than those detected in Pseudomonas aeruginosa PAO1. Cloning and introduction of the ohr and marR ORFs into Escherichia coli was associated with an increase in resistance to CHP and t-BHP. This appears to be the first case in which the genetic determinants involved in organic peroxide resistance are located in an extrachromosomal element, a situation that can facilitate the horizontal transfer of genetic elements coding for a function that protects bacterial cells from oxidative damage.
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Affiliation(s)
- Caleb W Dorsey
- Department of Microbiology, Miami University, Oxford, OH, USA
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McGillivary G, Smoot LM, Actis LA. Characterization of the IgA1 protease from the Brazilian purpuric fever strain F3031 of Haemophilus influenzae biogroup aegyptius. FEMS Microbiol Lett 2006; 250:229-36. [PMID: 16085369 DOI: 10.1016/j.femsle.2005.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Revised: 06/21/2005] [Accepted: 07/11/2005] [Indexed: 11/28/2022] Open
Abstract
Brazilian purpuric fever is a severe vascular disease caused by an invasive clone of Haemophilus influenzae biogroup aegyptius, which normally causes self-limiting eye infections. A previous genome subtraction procedure resulted in the isolation of a DNA fragment, which encodes a putative IgA1 protease, specific to the F3031 Brazilian purpuric fever type strain. Cloning and sequencing of the entire F3031 iga1 gene showed that the subtracted DNA fragment encompasses the iga1 region encoding the active site and the cleavage specificity determinant of the protein, which are different from the cognate regions of the proteases produced by other H. influenzae strains. Western and IgA cleavage assays together with clustering analysis showed that the F3031 IgA1 protease is most similar to the type 2 proteases produced by H. influenzae type c and e strains. Analysis of the promoter region of the F3031 iga1 gene revealed the presence of Fur binding sites. However, real-time PCR analysis and transcriptional fusion assays showed that the expression of iga1 is not regulated by iron or hemin under the conditions tested.
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Affiliation(s)
- Glen McGillivary
- Department of Microbiology, Miami University, 40 Pearson Hall, Oxford, OH 45056, USA
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Rhodes ER, Tomaras AP, McGillivary G, Connerly PL, Actis LA. Genetic and functional analyses of the Actinobacillus actinomycetemcomitans AfeABCD siderophore-independent iron acquisition system. Infect Immun 2005; 73:3758-63. [PMID: 15908408 PMCID: PMC1111845 DOI: 10.1128/iai.73.6.3758-3763.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Actinobacillus actinomycetemcomitans afeABCD iron transport system, the expression of which is controlled by iron and Fur, was identified in three different isolates. The protein products of this locus are related to bacterial ABC transporters involved in metal transport. Transformation of the Escherichia coli 1017 iron acquisition mutant with a plasmid harboring afeABCD promoted cell growth under iron-chelated conditions. However, insertion disruption of each of the afeABCD coding regions abolished this growth-relieving effect. The replacement of the parental afeA allele with the derivative afeA::EZ::TN<KAN-2> drastically reduced the ability of A. actinomycetemcomitans cells to grow under iron-chelated conditions.
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Affiliation(s)
- Eric R Rhodes
- Department of Microbiology, Miami University, 40 Pearson Hall, Oxford, OH 45056, USA
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McGillivary G, Tomaras AP, Rhodes ER, Actis LA. Cloning and sequencing of a genomic island found in the Brazilian purpuric fever clone of Haemophilus influenzae biogroup aegyptius. Infect Immun 2005; 73:1927-38. [PMID: 15784532 PMCID: PMC1087403 DOI: 10.1128/iai.73.4.1927-1938.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A genomic island was identified in the Haemophilus influenzae biogroup aegyptius Brazilian purpuric fever (BPF) strain F3031. This island, which was also found in other BPF isolates, could not be detected in non-BPF biogroup aegyptius strains or in nontypeable or typeable H. influenzae strains, with the exception of a region present in the type b Eagan strain. This 34,378-bp island is inserted, in reference to H. influenzae Rd KW20, within a choline transport gene and contains a mosaic structure of Mu-like prophage genes, several hypothetical genes, and genes potentially encoding an Erwinia carotovora carotovoricin Er-like bacteriocin. The product of the tail fiber ORF in the bacteriocin-like region shows a hybrid structure where the C terminus is similar to an H. influenzae phage HP1 tail protein implicating this open reading frame in altering host specificity for a putative bacteriocin. Significant synteny is seen in the entire genomic island with genomic regions from Salmonella enterica subsp. enterica serovar Typhi CT18, Photorhabdus luminescens subsp. laumondii TT01, Chromobacterium violaceum, and to a lesser extent Haemophilus ducreyi 35000HP. In a previous work, we isolated several BPF-specific DNA fragments through a genome subtraction procedure, and we have found that a majority of these fragments map to this locus. In addition, several subtracted fragments generated from an independent laboratory by using different but related strains also map to this island. These findings underscore the importance of this BPF-specific chromosomal region in explaining some of the genomic differences between highly invasive BPF strains and non-BPF isolates of biogroup aegyptius.
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Affiliation(s)
- Glen McGillivary
- Department of Microbiology, Miami University, 40 Pearson Hall, Oxford, OH 45056, USA
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Dorsey CW, Tomaras AP, Connerly PL, Tolmasky ME, Crosa JH, Actis LA. The siderophore-mediated iron acquisition systems of Acinetobacter baumannii ATCC 19606 and Vibrio anguillarum 775 are structurally and functionally related. Microbiology (Reading) 2004; 150:3657-3667. [PMID: 15528653 DOI: 10.1099/mic.0.27371-0] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
TheAcinetobacter baumanniitype strain, ATCC 19606, secretes acinetobactin, a catechol siderophore highly related to the iron chelator anguibactin produced by the fish pathogenVibrio anguillarum(Listonella anguillarum). This paper reports the initial characterization of the genes and gene products involved in the acinetobactin-mediated iron-acquisition process. Insertional mutagenesis resulted in the isolation of several derivatives whose ability to grow in medium containing the iron chelator 2,2′-dipyridyl was affected. One of the insertions disrupted a gene encoding a predicted outer-membrane protein, named BauA, highly similar to FatA, the receptor for ferric anguibactin. Immunological relatedness of BauA with FatA was confirmed by Western blot analysis. Another transposon insertion was mapped to a gene encoding a protein highly similar to FatD, the permease component of the anguibactin transport system. Further DNA sequencing and nucleotide sequence analysis revealed that theseA. baumannii19606 genes are part of a polycistronic locus that contains thebauDCEBAORFs. While the translation products ofbauD, -C, -Band -Aare highly related to theV. anguillarumFatDCBA iron-transport proteins, the product ofbauEis related to the ATPase component of Gram-positive ATP-binding cassette (ABC) transport systems. This entire locus is flanked by genes encoding predicted proteins related to AngU and AngN,V. anguillarumproteins required for the biosynthesis of anguibactin. These protein similarities, as well as the structural similarity of anguibactin and acinetobactin, suggested that these two siderophores could be utilized by both bacterial strains, a possibility that was confirmed by siderophore utilization bioassays. Taken together, these results demonstrate that these pathogens, which cause serious infections in unrelated hosts, express very similar siderophore-mediated iron-acquisition systems.
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Affiliation(s)
- Caleb W Dorsey
- Department of Microbiology, 40 Pearson Hall, Miami University, Oxford, OH 45056, USA
| | - Andrew P Tomaras
- Department of Microbiology, 40 Pearson Hall, Miami University, Oxford, OH 45056, USA
| | - Pamela L Connerly
- Department of Microbiology, 40 Pearson Hall, Miami University, Oxford, OH 45056, USA
| | - Marcelo E Tolmasky
- Department of Biological Science, California State University Fullerton, Fullerton, CA 92834-6850, USA
| | - Jorge H Crosa
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health Sciences University, Portland, OR 97201-3098, USA
| | - Luis A Actis
- Department of Microbiology, 40 Pearson Hall, Miami University, Oxford, OH 45056, USA
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