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Casella LG, Torres NJ, Tomlinson BR, Shepherd M, Shaw LN. The novel two-component system AmsSR governs alternative metabolic pathway usage in Acinetobacter baumannii. Front Microbiol 2023; 14:1139253. [PMID: 37082186 PMCID: PMC10112286 DOI: 10.3389/fmicb.2023.1139253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/15/2023] [Indexed: 04/22/2023] Open
Abstract
In this study, we identify a novel two-component system in Acinetobacter baumannii (herein named AmsSR for regulator of alternative metabolic systems) only present in select gammaproteobacterial and betaproteobacterial species. Bioinformatic analysis revealed that the histidine kinase, AmsS, contains 14 predicted N-terminal transmembrane domains and harbors a hybrid histidine kinase arrangement in its C-terminus. Transcriptional analysis revealed the proton ionophore CCCP selectively induces P amsSR expression. Disruption of amsSR resulted in decreased intracellular pH and increased depolarization of cytoplasmic membranes. Transcriptome profiling revealed a major reordering of metabolic circuits upon amsR disruption, with energy generation pathways typically used by bacteria growing in limited oxygen being favored. Interestingly, we observed enhanced growth rates for mutant strains in the presence of glucose, which led to overproduction of pyruvate. To mitigate the toxic effects of carbon overflow, we noted acetate overproduction in amsSR-null strains, resulting from a hyperactive Pta-AckA pathway. Additionally, due to altered expression of key metabolic genes, amsSR mutants favor an incomplete TCA cycle, relying heavily on an overactive glyoxylate shunt. This metabolic reordering overproduces NADH, which is not oxidized by the ETC; components of which were significantly downregulated upon amsSR disruption. As a result, the mutants almost exclusively rely on substrate phosphorylation for ATP production, and consequently display reduced oxygen consumption in the presence of glucose. Collectively, our data suggests that disruption of amsSR affects the function of the aerobic respiratory chain, impacting the energy status of the cell, which in turn upregulates alternative metabolic and energy generation pathways.
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Affiliation(s)
- Leila G. Casella
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, United States
| | - Nathanial J. Torres
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, United States
| | - Brooke R. Tomlinson
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, United States
| | - Mark Shepherd
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Lindsey N. Shaw
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, United States
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Fluorescence-Based Detection of Natural Transformation in Drug-Resistant Acinetobacter baumannii. J Bacteriol 2018; 200:JB.00181-18. [PMID: 30012729 PMCID: PMC6148472 DOI: 10.1128/jb.00181-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/27/2018] [Indexed: 01/05/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial agent with a high propensity for developing resistance to antibiotics. This ability relies on horizontal gene transfer mechanisms occurring in the Acinetobacter genus, including natural transformation. To study natural transformation in bacteria, the most prevalent method uses selection for the acquisition of an antibiotic resistance marker in a target chromosomal locus by the recipient cell. Most clinical isolates of A. baumannii are resistant to multiple antibiotics, limiting the use of such selection-based methods. Here, we report the development of a phenotypic and selection-free method based on flow cytometry to detect transformation events in multidrug-resistant (MDR) clinical A. baumannii isolates. To this end, we engineered a translational fusion between the abundant and conserved A. baumannii nucleoprotein (HU) and the superfolder green fluorescent protein (sfGFP). The new method was benchmarked against the conventional antibiotic selection-based method. Using this new method, we investigated several parameters affecting transformation efficiencies and identified conditions of transformability one hundred times higher than those previously reported. Using optimized transformation conditions, we probed natural transformation in a set of MDR clinical and nonclinical animal A. baumannii isolates. Regardless of their origin, the majority of the isolates displayed natural transformability, indicative of a conserved trait in the species. Overall, this new method and optimized protocol will greatly facilitate the study of natural transformation in the opportunistic pathogen A. baumannii IMPORTANCE Antibiotic resistance is a pressing global health concern with the rise of multiple and panresistant pathogens. The rapid and unfailing resistance to multiple antibiotics of the nosocomial agent Acinetobacter baumannii, notably to carbapenems, prompt to understand the mechanisms behind acquisition of new antibiotic resistance genes. Natural transformation, one of the horizontal gene transfer mechanisms in bacteria, was only recently described in A. baumannii and could explain its ability to acquire resistance genes. We developed a reliable method to probe and study natural transformation mechanism in A. baumannii More broadly, this new method based on flow cytometry will allow experimental detection and quantification of horizontal gene transfer events in multidrug-resistant A. baumannii.
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Uppuluri P, Lin L, Alqarihi A, Luo G, Youssef EG, Alkhazraji S, Yount NY, Ibrahim BA, Bolaris MA, Edwards JE, Swidergall M, Filler SG, Yeaman MR, Ibrahim AS. The Hyr1 protein from the fungus Candida albicans is a cross kingdom immunotherapeutic target for Acinetobacter bacterial infection. PLoS Pathog 2018; 14:e1007056. [PMID: 29746596 PMCID: PMC5963808 DOI: 10.1371/journal.ppat.1007056] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 05/22/2018] [Accepted: 04/26/2018] [Indexed: 11/21/2022] Open
Abstract
Different pathogens share similar medical settings and rely on similar virulence strategies to cause infections. We have previously applied 3-D computational modeling and bioinformatics to discover novel antigens that target more than one human pathogen. Active and passive immunization with the recombinant N-terminus of Candida albicans Hyr1 (rHyr1p-N) protect mice against lethal candidemia. Here we determine that Hyr1p shares homology with cell surface proteins of the multidrug resistant Gram negative bacterium, Acinetobacter baumannii including hemagglutinin (FhaB) and outer membrane protein A (OmpA). The A. baumannii OmpA binds to C. albicans Hyr1p, leading to a mixed species biofilm. Deletion of HYR1, or blocking of Hyr1p using polyclonal antibodies, significantly reduce A. baumannii binding to C. albicans hyphae. Furthermore, active vaccination with rHyr1p-N or passive immunization with polyclonal antibodies raised against specific peptide motifs of rHyr1p-N markedly improve survival of diabetic or neutropenic mice infected with A. baumannii bacteremia or pneumonia. Antibody raised against one particular peptide of the rHyr1p-N sequence (peptide 5) confers majority of the protection through blocking A. baumannii invasion of host cells and inducing death of the bacterium by a putative iron starvation mechanism. Anti-Hyr1 peptide 5 antibodies also mitigate A. baumannii /C. albicans mixed biofilm formation in vitro. Consistent with our bioinformatic analysis and structural modeling of Hyr1p, anti-Hyr1p peptide 5 antibodies bound to A. baumannii FhaB, OmpA, and an outer membrane siderophore binding protein. Our studies highlight the concept of cross-kingdom vaccine protection against high priority human pathogens such as A. baumannii and C. albicans that share similar ecological niches in immunocompromised patients.
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Affiliation(s)
- Priya Uppuluri
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Lin Lin
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Abdullah Alqarihi
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Guanpingsheng Luo
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Eman G. Youssef
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Biotechnology and Life Sciences, Faculty of Postgraduate Studies for Advanced Sciences (PSAS), Beni-Suef University, Beni-Suef, Egypt
| | - Sondus Alkhazraji
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Nannette Y. Yount
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Belal A. Ibrahim
- Portola High School, Irvine, California, United States of America
| | - Michael Anthony Bolaris
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - John E. Edwards
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Marc Swidergall
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Scott G. Filler
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Michael R. Yeaman
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Ashraf S. Ibrahim
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
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Tseng CC, Tsai YH, Hu A, Liou JW, Chang KC, Chang HH. Altered susceptibility to the bactericidal effect of photocatalytic oxidation by TiO2 is related to colistin resistance development in Acinetobacter baumannii. Appl Microbiol Biotechnol 2016; 100:8549-61. [DOI: 10.1007/s00253-016-7654-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/24/2016] [Accepted: 05/27/2016] [Indexed: 10/21/2022]
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Méndez JA, Mateos J, Beceiro A, Lopez M, Tomás M, Poza M, Bou G. Quantitative proteomic analysis of host--pathogen interactions: a study of Acinetobacter baumannii responses to host airways. BMC Genomics 2015; 16:422. [PMID: 26025090 PMCID: PMC4449591 DOI: 10.1186/s12864-015-1608-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 05/01/2015] [Indexed: 01/23/2023] Open
Abstract
Background Acinetobacter baumannii is a major health problem. The most common infection caused by A. baumannii is hospital acquired pneumonia, and the associated mortality rate is approximately 50 %. Neither in vivo nor ex vivo expression profiling has been performed at the proteomic or transcriptomic level for pneumonia caused by A. baumannii. In this study, we characterized the proteome of A. baumannii under conditions that simulate those found in the airways, to gain some insight into how A. baumannii adapts to the host and to improve knowledge about the pathogenesis and virulence of this bacterium. A clinical strain of A. baumannii was grown under different conditions: in the presence of bronchoalveolar lavage fluid from infected rats, of RAW 264.7 cells to simulate conditions in the respiratory tract and in control conditions. We used iTRAQ labelling and LC-MALDI-TOF/TOF to investigate how A. baumannii responds on exposure to macrophages/BALF. Results 179 proteins showed differential expression. In both models, proteins involved in the following processes were over-expressed: (i) pathogenesis and virulence (OmpA, YjjK); (ii) cell wall/membrane/envelope biogenesis (MurC); (iii) energy production and conversion (acetyl-CoA hydrolase); and (iv) translation (50S ribosomal protein L9). Proteins involved in the following were under-expressed: (i) lipid metabolism (short-chain dehydrogenase); (ii) amino acid metabolism and transport (aspartate aminotransferase); (iii) unknown function (DNA-binding protein); and (iv) inorganic ion transport and metabolism (hydroperoxidase). Conclusions We observed alterations in cell wall synthesis and identified 2 upregulated virulence-associated proteins with >15 peptides/protein in both ex vivo models (OmpA and YjjK), suggesting that these proteins are fundamental for pathogenesis and virulence in the airways. This study is the first comprehensive overview of the ex vivo proteome of A. baumannii and is an important step towards identification of diagnostic biomarkers, novel drug targets and potential vaccine candidates in the fight against pneumonia caused by A. baumannii. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1608-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jose Antonio Méndez
- Microbiology Division, INIBIC-Complejo Hospitalario Universitario de la Coruña, A Coruña, Spain.
| | - Jesús Mateos
- Grupo de Proteomica-PBR2-ProteoRed/ISCIII-Servicio de Reumatologia, A Coruña, Spain.
| | - Alejandro Beceiro
- Microbiology Division, INIBIC-Complejo Hospitalario Universitario de la Coruña, A Coruña, Spain.
| | - María Lopez
- Microbiology Division, INIBIC-Complejo Hospitalario Universitario de la Coruña, A Coruña, Spain.
| | - María Tomás
- Microbiology Division, INIBIC-Complejo Hospitalario Universitario de la Coruña, A Coruña, Spain.
| | - Margarita Poza
- Microbiology Division, INIBIC-Complejo Hospitalario Universitario de la Coruña, A Coruña, Spain.
| | - Germán Bou
- Microbiology Division, INIBIC-Complejo Hospitalario Universitario de la Coruña, A Coruña, Spain.
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A Commensal Strain of Staphylococcus epidermidis Overexpresses Membrane Proteins Associated with Pathogenesis When Grown in Biofilms. J Membr Biol 2015; 248:431-42. [PMID: 25837994 DOI: 10.1007/s00232-015-9801-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/26/2015] [Indexed: 11/26/2022]
Abstract
Staphylococcus epidermidis has emerged as one of the major nosocomial pathogens associated with infections of implanted medical devices. The most important factor in the pathogenesis of these infections is the formation of bacterial biofilms. Bacteria grown in biofilms are more resistant to antibiotics and to the immune defence system than planktonic bacteria. In these infections, the antimicrobial therapy usually fails and the removal of the biofilm-coated implanted device is the only effective solution. In this study, three proteomic approaches were performed to investigate membrane proteins associated to biofilm formation: (i) sample fractionation by gel electrophoresis, followed by isotopic labelling and LC-MS/MS analysis, (ii) in-solution sample preparation, followed by isotopic labelling and LC-MS/MS analysis and (iii) in-solution sample preparation and label-free LC-MS/MS analysis. We found that the commensal strain S. epidermidis CECT 231 grown in biofilms expressed higher levels of five membrane and membrane-associated proteins involved in pathogenesis: accumulation-associated protein, staphylococcal secretory antigen, signal transduction protein TRAP, ribonuclease Y and phenol soluble modulin beta 1 when compared with bacteria grown under planktonic conditions. These results indicate that a commensal strain can acquire a pathogenic phenotype depending on the mode of growth.
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7
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Tiwari V, Tiwari M. Quantitative proteomics to study carbapenem resistance in Acinetobacter baumannii. Front Microbiol 2014; 5:512. [PMID: 25309531 PMCID: PMC4176082 DOI: 10.3389/fmicb.2014.00512] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 09/11/2014] [Indexed: 12/28/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen causing pneumonia, respiratory infections and urinary tract infections. The prevalence of this lethal pathogen increases gradually in the clinical setup where it can grow on artificial surfaces, utilize ethanol as a carbon source. Moreover it resists desiccation. Carbapenems, a β-lactam, are the most commonly prescribed drugs against A. baumannii. Resistance against carbapenem has emerged in Acinetobacter baumannii which can create significant health problems and is responsible for high morbidity and mortality. With the development of quantitative proteomics, a considerable progress has been made in the study of carbapenem resistance of Acinetobacter baumannii. Recent updates showed that quantitative proteomics has now emerged as an important tool to understand the carbapenem resistance mechanism in Acinetobacter baumannii. Present review also highlights the complementary nature of different quantitative proteomic methods used to study carbapenem resistance and suggests to combine multiple proteomic methods for understanding the response to antibiotics by Acinetobacter baumannii.
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Affiliation(s)
- Vishvanath Tiwari
- Department of Biochemistry, Central University of RajasthanAjmer, India
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Fajardo Bonin R, Chapeaurouge A, Perales J, da Silva JG, do Nascimento HJ, D'Alincourt Carvalho Assef AP, Moreno Senna JP. Identification of immunogenic proteins of the bacterium Acinetobacter baumannii using a proteomic approach. Proteomics Clin Appl 2014; 8:916-23. [PMID: 24899143 DOI: 10.1002/prca.201300133] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 04/08/2014] [Accepted: 05/28/2014] [Indexed: 11/11/2022]
Abstract
PURPOSE Acinetobacter baumannii is an important opportunistic pathogen that causes pneumoniae, urinary tract infections, and/or septicemia in immunocompromised patients. This pathogen is frequently associated with nosocomial outbreaks worldwide and has become particularly problematic because of its prevalence and resistance patterns to several antibiotics. In the present study, we used an immunoproteome-based approach to identify immunogenic proteins located on the surface of A. baumannii for the development of a possible immunotherapy against this devastating bacterial infection. EXPERIMENTAL DESIGN Sera from patients with A. baumannii infections (n = 50) and from a control group of healthy individuals (n = 3) were analyzed for reactivity against A. baumannii outer membrane proteins (OMPs) using Western blot analysis. To identify potential immunogenic proteins in A. baumannii, OMPs were separated by 2DE, and reactive sera from infected patients were randomly selected and divided into two different pools, each containing 15 sera. Finally, MALDI-TOF/TOF mass spectrometric analysis was employed to identify the corresponding proteins. RESULTS This analysis identified six immunoreactive proteins: OmpA, Omp34kDa, OprC, OprB-like, OXA-23, and ferric siderophore receptor protein. Notably, these proteins are highly abundant on the bacterial surface and involved in virulence, antibiotic resistance, and growth. CONCLUSIONS AND CLINICAL RELEVANCE Our results support the notion that the proteins identified in the present immunoproteome study could serve as antigen candidates for the development of vaccines and passive immunotherapies against A. baumannii infections.
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Li X, Bai T, Li Y, Ruan X, Li H. Proteomic analysis of Fusarium oxysporum f. sp. cubense tropical race 4-inoculated response to Fusarium wilts in the banana root cells. Proteome Sci 2013; 11:41. [PMID: 24070062 PMCID: PMC3850410 DOI: 10.1186/1477-5956-11-41] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 09/22/2013] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Fusarium wilt of banana is one of the most destructive diseases in the world. This disease has caused heavy losses in major banana production areas. Except for molecular breeding methods based on plant defense mechanisms, effective methods to control the disease are still lacking. Dynamic changes in defense mechanisms between susceptible, moderately resistant, and highly resistant banana and Fusarium oxysporum f. sp. cubense tropical race 4 (Foc4) at the protein level remain unknown. This research reports the proteomic profile of three banana cultivars in response to Foc4 and transcriptional levels correlated with their sequences for the design of disease control strategies by molecular breeding. RESULTS Thirty-eight differentially expressed proteins were identified to function in cell metabolism. Most of these proteins were positively regulated after Foc4 inoculation. These differentially regulated proteins were found to have important functions in banana defense response. Functional categories implicated that these proteins were associated with pathogenesis-related (PR) response; isoflavonoid, flavonoid, and anthocyanin syntheses; cell wall strengthening; cell polarization; reactive oxygen species production and scavenging; jasmonic acid-, abscisic acid-, and auxin-mediated signaling conduction; molecular chaperones; energy; and primary metabolism. By comparing the protein profiles of resistant and susceptible banana cultivars, many proteins showed obvious distinction in their defense mechanism functions. PR proteins in susceptible 'Brazil' were mainly involved in defense. The proteins related to PR response, cell wall strengthening and antifungal compound synthesis in moderately resistant 'Nongke No.1' were mainly involved in defense. The proteins related to PR response, cell wall strengthening, and antifungal compound synthesis in highly resistant 'Yueyoukang I' were mainly involved in defense. 12 differentially regulated genes were selected to validate through quantitative real time PCR method. Quantitative RT-PCR analyses of these selected genes corroborate with their respective protein abundance after pathogen infection. CONCLUSIONS This report is the first to use proteomic profiling to study the molecular mechanism of banana roots infected with Foc4. The differentially regulated proteins involved in different defense pathways are likely associated with different resistant levels of the three banana cultivars.
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Affiliation(s)
- Xingshen Li
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou, Guangdong 510642, China
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Tingting Bai
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou, Guangdong 510642, China
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Yunfeng Li
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Xiaolei Ruan
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou, Guangdong 510642, China
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
| | - Huaping Li
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou, Guangdong 510642, China
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China
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Beceiro A, Tomás M, Bou G. Antimicrobial resistance and virulence: a successful or deleterious association in the bacterial world? Clin Microbiol Rev 2013; 26:185-230. [PMID: 23554414 PMCID: PMC3623377 DOI: 10.1128/cmr.00059-12] [Citation(s) in RCA: 616] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hosts and bacteria have coevolved over millions of years, during which pathogenic bacteria have modified their virulence mechanisms to adapt to host defense systems. Although the spread of pathogens has been hindered by the discovery and widespread use of antimicrobial agents, antimicrobial resistance has increased globally. The emergence of resistant bacteria has accelerated in recent years, mainly as a result of increased selective pressure. However, although antimicrobial resistance and bacterial virulence have developed on different timescales, they share some common characteristics. This review considers how bacterial virulence and fitness are affected by antibiotic resistance and also how the relationship between virulence and resistance is affected by different genetic mechanisms (e.g., coselection and compensatory mutations) and by the most prevalent global responses. The interplay between these factors and the associated biological costs depend on four main factors: the bacterial species involved, virulence and resistance mechanisms, the ecological niche, and the host. The development of new strategies involving new antimicrobials or nonantimicrobial compounds and of novel diagnostic methods that focus on high-risk clones and rapid tests to detect virulence markers may help to resolve the increasing problem of the association between virulence and resistance, which is becoming more beneficial for pathogenic bacteria.
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11
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Liou ML, Soo PC, Ling SR, Kuo HY, Tang CY, Chang KC. The sensor kinase BfmS mediates virulence in Acinetobacter baumannii. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2013; 47:275-81. [PMID: 23453128 DOI: 10.1016/j.jmii.2012.12.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 11/15/2012] [Accepted: 12/17/2012] [Indexed: 11/18/2022]
Abstract
BACKGROUND/PURPOSE BfmR, the response regulator component of the two-component system BfmRS, has important roles in biofilm formation and cellular morphology of Acinetobacter baumannii. Until now, the contribution of the sensor kinase BfmS to the virulence of this bacterium remains unknown. In this study, a bfmS knockout and complementation studies were performed to clarify the role of BfmS in A. baumannii virulence. METHODS We constructed a bfmS knockout mutant in the A. baumannii 17978 type strain by transposon inactivation. To clarify the role of bfmS in A. baumannii virulence, the biofilm formation, adherence ability to eukaryotic cells, serum resistance, and antibiotic susceptibility tests were performed in A. baumannii 17978 and its derivative knockout and complementation strains. RESULTS The bfmS knockout displayed a reduction in biofilm formation, loss of adherence to eukaryotic cells, and greater sensitivity to serum killing compared with the parent strain. Proteomic analysis of culture supernatants revealed that the release of outer membrane proteins (Omps), including CarO and outer membrane protein A (OmpA), was associated with the inactivation of BfmS in A. baumannii. CONCLUSION This study is the first to demonstrate that the pathway regulated by the sensor kinase BfmS is associated with biofilm formation, adherence to biotic surfaces, serum resistance, and antibiotic susceptibility, which may be associated with the release of Omps in A. baumannii.
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Affiliation(s)
- Ming-Li Liou
- Department of Medical Laboratory Science and Biotechnology, Yuanpei University, Hsin-Chu City, Taiwan; Department of Computer Science and Information Engineering, Providence University, Taichung County, Taiwan
| | - Po-Chi Soo
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien, Taiwan
| | - Siao-Ru Ling
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien, Taiwan
| | - Han-Yueh Kuo
- Department of Medicine, National Taiwan University Hospital, Hsin-Chu Branch, Hsin-Chu City, Taiwan; School of Medicine, National Yang-Ming University, New Taipei City, Taiwan
| | - Chuan Yi Tang
- Department of Computer Science and Information Engineering, Providence University, Taichung County, Taiwan
| | - Kai-Chih Chang
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien, Taiwan; Department of Laboratory Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan.
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12
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Chang CJ, Lin JH, Chang KC, Lai MJ, Rohini R, Hu A. Diagnosis of β-Lactam Resistance in Acinetobacter baumannii Using Shotgun Proteomics and LC-Nano-Electrospray Ionization Ion Trap Mass Spectrometry. Anal Chem 2013; 85:2802-8. [DOI: 10.1021/ac303326a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Chih-Jui Chang
- Department of Molecular Biology and
Human Genetics, Tzu Chi University, Hualien
970, Taiwan
| | - Jyun-Han Lin
- Department
of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 970, Taiwan
| | - Kai-Chih Chang
- Department
of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 970, Taiwan
- Buddhist Tzu Chi General Hospital, Hualien 970, Taiwan
| | - Meng-Jiun Lai
- Department
of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 970, Taiwan
| | - Rondla Rohini
- Department
of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 970, Taiwan
| | - Anren Hu
- Department
of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 970, Taiwan
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13
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Mendez JA, Soares NC, Mateos J, Gayoso C, Rumbo C, Aranda J, Tomas M, Bou G. Extracellular Proteome of a Highly Invasive Multidrug-resistant Clinical Strain of Acinetobacter baumannii. J Proteome Res 2012; 11:5678-94. [DOI: 10.1021/pr300496c] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jose Antonio Mendez
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Nelson C. Soares
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Jesús Mateos
- Unidad de Proteómica, INIBIC, As Xubias s/n, La Coruña, Spain
| | - Carmen Gayoso
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Carlos Rumbo
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Jesús Aranda
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Maria Tomas
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Germán Bou
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
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14
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Tiwari V, Vashistt J, Kapil A, Moganty RR. Comparative proteomics of inner membrane fraction from carbapenem-resistant Acinetobacter baumannii with a reference strain. PLoS One 2012; 7:e39451. [PMID: 22761799 PMCID: PMC3383706 DOI: 10.1371/journal.pone.0039451] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/21/2012] [Indexed: 12/31/2022] Open
Abstract
Acinetobacter baumannii has been identified by the Infectious Diseases Society of America as one of the six pathogens that cause majority of hospital infections. Increased resistance of A.baumannii even to the latest generation of β-lactams like carbapenem is an immediate threat to mankind. As inner-membrane fraction plays a significant role in survival of A.baumannii, we investigated the inner-membrane fraction proteome of carbapenem-resistant strain of A.baumannii using Differential In-Gel Electrophoresis (DIGE) followed by DeCyder, Progenesis and LC-MS/MS analysis. We identified 19 over-expressed and 4 down-regulated proteins (fold change>2, p<0.05) in resistant strain as compared to reference strain. Some of the upregulated proteins in resistant strain and their association with carbapenem resistance in A.baumannii are: i) β-lactamases, AmpC and OXA-51: cleave and inactivate carbapenem ii) metabolic enzymes, ATP synthase, malate dehydrogenase and 2-oxoglutarate dehydrogenase: help in increased energy production for the survival and iii) elongation factor Tu and ribosomal proteins: help in the overall protein production. Further, entry of carbapenem perhaps is limited by controlled production of OmpW and low levels of surface antigen help to evade host defence mechanism in developing resistance in A.baumannii. Present results support a model for the importance of proteins of inner-membrane fraction and their synergistic effect in the mediation of resistance of A.baumannii to carbapenem.
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Affiliation(s)
- Vishvanath Tiwari
- Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Jitendraa Vashistt
- Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Arti Kapil
- Department of Microbiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Rajeswari R. Moganty
- Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
- * E-mail:
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15
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Beceiro A, Tomás M, Bou G. [Antimicrobial resistance and virulence: a beneficial relationship for the microbial world?]. Enferm Infecc Microbiol Clin 2012; 30:492-9. [PMID: 22385639 DOI: 10.1016/j.eimc.2012.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 01/01/2012] [Indexed: 11/28/2022]
Abstract
While bacterial virulence has experienced a long host/pathogen-dependent evolutionary process, antimicrobial resistance has had a very different, shorting and changing evolution due to the biological pressure caused by the introduction of the antimicrobials in human medicine. This strong pressure has forced the microorganisms to adapt to these changing conditions, continuously acquiring or developing new resistance mechanisms, causing major changes in cellular functions and finally influencing the virulence and bacterial fitness. Multiple factors may mediate in the relationship between virulence and resistance. The genes often involved in both phenomena have the same transport and dispersion mediums. Islands, integrons, transposons and other genetic elements could also facilitate the combined selection of virulence and resistance genes. The increase in resistance can affect virulence in different ways, mainly depending on the bacterial species, the environment, and the mechanism of resistance. This review presents the different phenomena in which the genetic mechanism that provides an advantage over the antimicrobials directly affects the virulence and fitness, such as changes in the structure of the cellular wall, efflux pumps, porins or two-component regulatory systems. The co-selection of virulence and antimicrobial resistance factors and the relative ease of bacteria to develop compensatory mutations can favour, particularly in environments with high antibiotic pressure, the emergence of prevalent clones. These can be virulent and with few treatment options, and could be a major health problem in the near future.
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Affiliation(s)
- Alejandro Beceiro
- Servizo de Microbioloxía-INIBIC, Complexo Hospitalario Universitario A Coruña, A Coruña, España.
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16
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Active and passive immunization protects against lethal, extreme drug resistant-Acinetobacter baumannii infection. PLoS One 2012; 7:e29446. [PMID: 22253723 PMCID: PMC3254619 DOI: 10.1371/journal.pone.0029446] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 11/28/2011] [Indexed: 12/04/2022] Open
Abstract
Extreme-drug-resistant (XDR) Acinetobacter baumannii is a rapidly emerging pathogen causing infections with unacceptably high mortality rates due to inadequate available treatment. New methods to prevent and treat such infections are a critical unmet medical need. To conduct a rational vaccine discovery program, OmpA was identified as the primary target of humoral immune response after intravenous infection by A. baumannii in mice. OmpA was >99% conserved at the amino acid level across clinical isolates harvested between 1951 and 2009 from cerebrospinal fluid, blood, lung, and wound infections, including carbapenem-resistant isolates, and was ≥89% conserved among other sequenced strains, but had minimal homology to the human proteome. Vaccination of diabetic mice with recombinant OmpA (rOmpA) with aluminum hydroxide adjuvant markedly improved survival and reduced tissue bacterial burden in mice infected intravenously. Vaccination induced high titers of anti-OmpA antibodies, the levels of which correlated with survival in mice. Passive transfer with immune sera recapitulated protection. Immune sera did not enhance complement-mediated killing but did enhance opsonophagocytic killing of A. baumannii. These results define active and passive immunization strategies to prevent and treat highly lethal, XDR A. baumannii infections.
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17
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Cabral MP, Soares NC, Aranda J, Parreira JR, Rumbo C, Poza M, Valle J, Calamia V, Lasa Í, Bou G. Proteomic and Functional Analyses Reveal a Unique Lifestyle for Acinetobacter baumannii Biofilms and a Key Role for Histidine Metabolism. J Proteome Res 2011; 10:3399-417. [DOI: 10.1021/pr101299j] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Maria P. Cabral
- Laboratorio de Microbiología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC), As Xubias s/n; La Coruña, Spain
| | - Nelson C. Soares
- Laboratorio de Microbiología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC), As Xubias s/n; La Coruña, Spain
| | - Jesús Aranda
- Laboratorio de Microbiología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC), As Xubias s/n; La Coruña, Spain
| | - José R. Parreira
- Laboratorio de Microbiología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC), As Xubias s/n; La Coruña, Spain
| | - Carlos Rumbo
- Laboratorio de Microbiología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC), As Xubias s/n; La Coruña, Spain
| | - Margarita Poza
- Laboratorio de Microbiología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC), As Xubias s/n; La Coruña, Spain
| | - Jaione Valle
- Laboratorio de Biofilms Microbianos, Instituto de Agrobiotecnología, Universidad Pública de Navarra-CSIC, Pamplona, Spain
| | | | - Íñigo Lasa
- Laboratorio de Biofilms Microbianos, Instituto de Agrobiotecnología, Universidad Pública de Navarra-CSIC, Pamplona, Spain
| | - Germán Bou
- Laboratorio de Microbiología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC), As Xubias s/n; La Coruña, Spain
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18
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Horizontal transfer of the OXA-24 carbapenemase gene via outer membrane vesicles: a new mechanism of dissemination of carbapenem resistance genes in Acinetobacter baumannii. Antimicrob Agents Chemother 2011; 55:3084-90. [PMID: 21518847 DOI: 10.1128/aac.00929-10] [Citation(s) in RCA: 242] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The resistance of Acinetobacter baumannii strains to carbapenems is a worrying problem in hospital settings. The main mechanism of carbapenem resistance is the expression of β-lactamases (metalloenzymes or class D enzymes). The mechanisms of the dissemination of these genes among A. baumannii strains are not fully understood. In this study we used two carbapenem-resistant clinical strains of A. baumannii (AbH12O-A2 and AbH12O-CU3) expressing the plasmid-borne bla(OXA-24) gene (plasmids pMMA2 and pMMCU3, respectively) to demonstrate that A. baumannii releases outer membrane vesicles (OMVs) during in vitro growth. The use of hybridization studies enabled us to show that these OMVs harbored the bla(OXA-24) gene. The incubation of these OMVs with the carbapenem-susceptible A. baumannii ATCC 17978 host strain yielded full resistance to carbapenems. The presence of the original plasmids harboring the bla(OXA-24) gene was detected in strain ATCC 17978 after the transformation of OMVs. New OMVs harboring bla(OXA-24) were released by A. baumannii ATCC 17978 after it was transformed with the original OMV-mediated plasmids, indicating the universality of the process. We present the first experimental evidence that clinical isolates of A. baumannii may release OMVs as a mechanism of horizontal gene transfer whereby carbapenem resistance genes are delivered to surrounding A. baumannii bacterial isolates.
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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] [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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20
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Yun SH, Choi CW, Kwon SO, Park GW, Cho K, Kwon KH, Kim JY, Yoo JS, Lee JC, Choi JS, Kim S, Kim SI. Quantitative proteomic analysis of cell wall and plasma membrane fractions from multidrug-resistant Acinetobacter baumannii. J Proteome Res 2010; 10:459-69. [PMID: 21053951 DOI: 10.1021/pr101012s] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Acinetobacter baumannii is a Gram-negative, nonmotile aerobic bacterium that has emerged as an important nosocomial pathogen. Multidrug-resistant (MDR) A. baumannii is difficult to treat with antibiotics, and treatment failure in infected patients is of great concern in clinical settings. To investigate proteome regulation in A. baumannii under antibiotic stress conditions, quantitative membrane proteomic analyses of a clinical MDR A. baumannii strain cultured in subminimal inhibitory concentrations of tetracycline and imipenem were performed using a combination of label-free (one-dimensional electrophoresis-liquid chromatography-tandem mass spectrometry) and label (isobaric tag for relative and absolute quantitation) approaches. In total, 484 proteins were identified, and 302 were classified as outer membrane, periplasmic, or plasma membrane proteins. The clinical A. baumannii strain DU202 responded specifically and induced different cell wall and membrane protein sets that provided resistance to the antibiotics. The induction of resistance-nodulation-cell division transporters and protein kinases, and the repression of outer membrane proteins were common responses in the presence of tetracycline and imipenem. Induction of a tetracycline resistant pump, ribosomal proteins, and iron-uptake transporters appeared to be dependent on tetracycline conditions, whereas β-lactamase and penicillin-binding proteins appeared to be dependent on imipenem conditions. These results suggest that combined liquid chromatography-based proteomic approaches can be used to identify cell wall and membrane proteins involved in the antibiotic resistance of A. baumannii.
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Affiliation(s)
- Sung-Ho Yun
- Division of Life Science, Korea Basic Science Institute, Daejeon, Korea
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21
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Aranda J, Poza M, Pardo BG, Rumbo S, Rumbo C, Parreira JR, Rodríguez-Velo P, Bou G. A rapid and simple method for constructing stable mutants of Acinetobacter baumannii. BMC Microbiol 2010; 10:279. [PMID: 21062436 PMCID: PMC2993698 DOI: 10.1186/1471-2180-10-279] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 11/09/2010] [Indexed: 01/06/2023] Open
Abstract
Background Acinetobacter baumannii is a multidrug-resistant bacterium responsible for nosocomial infections in hospitals worldwide. Study of mutant phenotypes is fundamental for understanding gene function. The methodologies developed to inactivate A. baumannii genes are complicated and time-consuming; sometimes result in unstable mutants, and do not enable construction of double (or more) gene knockout mutant strains of A. baumannii. Results We describe here a rapid and simple method of obtaining A. baumannii mutants by gene replacement via double crossover recombination, by use of a PCR product that carries an antibiotic resistance cassette flanked by regions homologous to the target locus. To demonstrate the reproducibility of the approach, we produced mutants of three different chromosomal genes (omp33, oxyR, and soxR) by this method. In addition, we disrupted one of these genes (omp33) by integration of a plasmid into the chromosome by single crossover recombination, the most widely used method of obtaining A. baumannii mutants. Comparison of the different techniques revealed absolute stability when the gene was replaced by a double recombination event, whereas up to 40% of the population reverted to wild-type when the plasmid was disrupting the target gene after 10 passages in broth without selective pressure. Moreover, we demonstrate that the combination of both gene disruption and gene replacement techniques is an easy and useful procedure for obtaining double gene knockout mutants in A. baumannii. Conclusions This study provides a rapid and simple method of obtaining stable mutants of A. baumannii free of foreign plasmidic DNA, which does not require cloning steps, and enables construction of multiple gene knockout mutants.
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Affiliation(s)
- Jesús Aranda
- Servizo de Microbioloxía-INIBIC, Complexo Hospitalario Universitario A Coruña, 15006,A Coruña, Spain
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22
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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] [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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23
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Rahbar MR, Rasooli I, Mousavi Gargari SL, Amani J, Fattahian Y. In silico analysis of antibody triggering biofilm associated protein in Acinetobacter baumannii. J Theor Biol 2010; 266:275-90. [PMID: 20600143 DOI: 10.1016/j.jtbi.2010.06.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2010] [Revised: 06/07/2010] [Accepted: 06/08/2010] [Indexed: 12/24/2022]
Abstract
Acinetobacter baumannii surface protein, commonly known as biofilm associated protein (Bap), is involved in biofilm formation. A high propensity among the clinical isolates to form biofilm and a significant association of biofilms with multiple drug resistance has been demonstrated. Production of antibodies can be used for inhibition of biofilm and control of the diseases caused by A. baumannii. Large molecular mass of Bap justifies an approach to identifying A. baumannii effective antigens. It has a core domain of seven repeat modules A-G. With the large number of available biofilm gene sequences, bioinformatic tools are needed to identify the genes encoding the antigens. Proteins containing these tandem repeats of Bap domains have high propensities to attach to each other to form biofilm. We hypothesized that conserved and functional domains of tandem repeat could be identified with a search and alignment of the repeats for evaluation of antigenic determinants. Here we demonstrate the results of bioinformatics screening and gene scan of the gene sequence database of homolog sequences to identify conserved domains. Higher scoring hits were found in repeat modules mostly D, B, C and A, respectively. Upon the analysis four regions of highly structural and functional conserved regions from Bap sequence of A. baumannii were selected. 3D structure, antigenicity and solubility predictions revealed that these regions were appropriate candidates for antibody production.
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Affiliation(s)
- Mohammad Reza Rahbar
- Department of Biology, Shahed University, Tehran-Qom Express Way, Opposite Imam Khomeini's Shrine, Tehran 3319118651, Iran
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Soares NC, Cabral MP, Gayoso C, Mallo S, Rodriguez-Velo P, Fernández-Moreira E, Bou G. Associating Growth-Phase-Related Changes in the Proteome of Acinetobacter baumannii with Increased Resistance to Oxidative Stress. J Proteome Res 2010; 9:1951-64. [DOI: 10.1021/pr901116r] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Nelson C. Soares
- Servicio de Microbiologia-INIBIC, Complejo Hospitalario Universitario La Coruña, As Xubias s/n, 15006 La Coruña, Spain
| | - Maria P. Cabral
- Servicio de Microbiologia-INIBIC, Complejo Hospitalario Universitario La Coruña, As Xubias s/n, 15006 La Coruña, Spain
| | - Carmen Gayoso
- Servicio de Microbiologia-INIBIC, Complejo Hospitalario Universitario La Coruña, As Xubias s/n, 15006 La Coruña, Spain
| | - Susana Mallo
- Servicio de Microbiologia-INIBIC, Complejo Hospitalario Universitario La Coruña, As Xubias s/n, 15006 La Coruña, Spain
| | - Patricia Rodriguez-Velo
- Servicio de Microbiologia-INIBIC, Complejo Hospitalario Universitario La Coruña, As Xubias s/n, 15006 La Coruña, Spain
| | - Esteban Fernández-Moreira
- Servicio de Microbiologia-INIBIC, Complejo Hospitalario Universitario La Coruña, As Xubias s/n, 15006 La Coruña, Spain
| | - Germán Bou
- Servicio de Microbiologia-INIBIC, Complejo Hospitalario Universitario La Coruña, As Xubias s/n, 15006 La Coruña, Spain
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