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Burch-Konda J, Kayastha BB, Kubo A, Achour M, Hull M, Braga R, Winton L, Rogers RR, McCoy J, Lutter EI, Patrauchan MA. EF-Hand Calcium Sensor, EfhP, Controls Transcriptional Regulation of Iron Uptake by Calcium in Pseudomonas aeruginosa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.09.574892. [PMID: 38260268 PMCID: PMC10802428 DOI: 10.1101/2024.01.09.574892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The human pathogen Pseudomonas aeruginosa poses a major risk for a range of severe infections, particularly lung infections in patients suffering from cystic fibrosis (CF). As previously reported, the virulent behavior of this pathogen is enhanced by elevated levels of Ca 2+ that are commonly present in CF nasal and lung fluids. In addition, a Ca 2+ -binding EF-hand protein, EfhP (PA4107), was partially characterized and shown to be critical for the Ca 2+ -regulated virulence in P. aeruginosa . Here we describe the rapid (10 min, 60 min), and adaptive (12 h) transcriptional responses of PAO1 to elevated Ca 2+ detected by genome-wide RNA sequencing and show that efhP deletion significantly hindered both rapid and adaptive Ca 2+ regulation. The most differentially regulated genes included multiple Fe sequestering mechanisms, a large number of extracytoplasmic function sigma factors (ECFσ) and several virulence factors, such as production of pyocins. The Ca 2+ regulation of Fe uptake was also observed in CF clinical isolates and appeared to involve the global regulator Fur. In addition, we showed that the efhP transcription is controlled by Ca 2+ and Fe, and this regulation required Ca 2+ -dependent two-component regulatory system CarSR. Furthermore, the efhP expression is significantly increased in CF clinical isolates and upon pathogen internalization into epithelial cells. Overall, the results established for the first time that Ca 2+ controls Fe sequestering mechanisms in P. aeruginosa and that EfhP plays a key role in the regulatory interconnectedness between Ca 2+ and Fe signaling pathways, the two distinct and important signaling pathways that guide the pathogen's adaptation to host. IMPORTANCE Pseudomonas aeruginosa ( Pa ) poses a major risk for severe infections, particularly in patients suffering from cystic fibrosis (CF). For the first time, kinetic RNA sequencing analysis identified Pa rapid and adaptive transcriptional responses to Ca 2+ levels consistent with those present in CF respiratory fluids. The most highly upregulated processes include iron sequestering, iron starvation sigma factors, and self-lysis factors pyocins. An EF-hand Ca 2+ sensor, EfhP, is required for at least 1/3 of the Ca 2+ response, including all the iron uptake mechanisms and production of pyocins. Transcription of efhP itself is regulated by Ca 2+ , Fe, and increases during interactions with host epithelial cells, suggesting the protein's important role in Pa infections. The findings establish the regulatory interconnectedness between Ca 2+ and iron signaling pathways that shape Pa transcriptional responses. Therefore, understanding Pa's transcriptional response to Ca 2+ and associated regulatory mechanisms will serve the development of future therapeutics targeting Pa dangerous infections.
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Sánchez-Gil JJ, Poppeliers SWM, Vacheron J, Zhang H, Odijk B, Keel C, de Jonge R. The conserved iol gene cluster in Pseudomonas is involved in rhizosphere competence. Curr Biol 2023; 33:3097-3110.e6. [PMID: 37419116 DOI: 10.1016/j.cub.2023.05.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/25/2023] [Accepted: 05/24/2023] [Indexed: 07/09/2023]
Abstract
The Pseudomonas genus has shown great potential as a sustainable solution to support agriculture through its plant-growth-promoting and biocontrol activities. However, their efficacy as bioinoculants is limited by unpredictable colonization in natural conditions. Our study identifies the iol locus, a gene cluster in Pseudomonas involved in inositol catabolism, as a feature enriched among superior root colonizers in natural soil. Further characterization revealed that the iol locus increases competitiveness, potentially caused by an observed induction of swimming motility and the production of fluorescent siderophore in response to inositol, a plant-derived compound. Public data analyses indicate that the iol locus is broadly conserved in the Pseudomonas genus and linked to diverse host-microbe interactions. Together, our findings suggest the iol locus as a potential target for developing more effective bioinoculants for sustainable agriculture.
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Affiliation(s)
- Juan J Sánchez-Gil
- Plant-Microbe Interactions, Department of Biology, Science for Life, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Sanne W M Poppeliers
- Plant-Microbe Interactions, Department of Biology, Science for Life, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Jordan Vacheron
- Department of Fundamental Microbiology, University of Lausanne, Lausanne CH-1015, Switzerland
| | - Hao Zhang
- Plant-Microbe Interactions, Department of Biology, Science for Life, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Bart Odijk
- Plant-Microbe Interactions, Department of Biology, Science for Life, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Christoph Keel
- Department of Fundamental Microbiology, University of Lausanne, Lausanne CH-1015, Switzerland
| | - Ronnie de Jonge
- Plant-Microbe Interactions, Department of Biology, Science for Life, Utrecht University, Utrecht 3584 CH, The Netherlands.
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Regulatory Landscape of the Pseudomonas aeruginosa Phosphoethanolamine Transferase Gene eptA in the Context of Colistin Resistance. Antibiotics (Basel) 2023; 12:antibiotics12020200. [PMID: 36830112 PMCID: PMC9952513 DOI: 10.3390/antibiotics12020200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/14/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Pseudomonas aeruginosa has the genetic potential to acquire colistin resistance through the modification of lipopolysaccharide by the addition of 4-amino-4-deoxy-L-arabinose (L-Ara4N) or phosphoethanolamine (PEtN), mediated by the arn operon or the eptA gene, respectively. However, in vitro evolution experiments and genetic analysis of clinical isolates indicate that lipopolysaccharide modification with L-Ara4N is invariably preferred over PEtN addition as the colistin resistance mechanism in this bacterium. Since little is known about eptA regulation in P. aeruginosa, we generated luminescent derivatives of the reference strain P. aeruginosa PAO1 to monitor arn and eptA promoter activity. We performed transposon mutagenesis assays to compare the likelihood of acquiring mutations leading to arn or eptA induction and to identify eptA regulators. The analysis revealed that eptA was slightly induced under certain stress conditions, such as arginine or biotin depletion and accumulation of the signal molecule diadenosine tetraphosphate, but the induction did not confer colistin resistance. Moreover, we demonstrated that spontaneous mutations leading to colistin resistance invariably triggered arn rather than eptA expression, and that eptA was not induced in resistant mutants upon colistin exposure. Overall, these results suggest that the contribution of eptA to colistin resistance in P. aeruginosa may be limited by regulatory restraints.
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Hamza EH, El-Shawadfy AM, Allam AA, Hassanein WA. Study on pyoverdine and biofilm production with detection of LasR gene in MDR Pseudomonas aeruginosa. Saudi J Biol Sci 2022; 30:103492. [DOI: 10.1016/j.sjbs.2022.103492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 10/08/2022] [Accepted: 11/07/2022] [Indexed: 11/13/2022] Open
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5
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Pseudomonas aeruginosa Strains from Both Clinical and Environmental Origins Readily Adopt a Stable Small-Colony-Variant Phenotype Resulting from Single Mutations in c-di-GMP Pathways. J Bacteriol 2022; 204:e0018522. [PMID: 36102640 PMCID: PMC9578426 DOI: 10.1128/jb.00185-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A subpopulation of small-colony variants (SCVs) is a frequently observed feature of Pseudomonas aeruginosa isolates obtained from colonized cystic fibrosis lungs. Since most SCVs have until now been isolated from clinical samples, it remains unclear how widespread the ability of P. aeruginosa strains to develop this phenotype is and what the genetic mechanism(s) behind the emergence of SCVs are according to the origin of the isolate. In the present work, we investigated the ability of 22 P. aeruginosa isolates from various environmental origins to spontaneously adopt an SCV-like smaller alternative morphotype distinguishable from that of the ancestral parent strain under laboratory culture conditions. We found that all the P. aeruginosa strains tested could adopt an SCV phenotype, regardless of their origin. Whole-genome sequencing of SCVs obtained from clinical and environmental sources revealed single mutations exclusively in two distinct c-di-GMP signaling pathways, the Wsp and YfiBNR pathways. We conclude that the ability to switch to an SCV phenotype is a conserved feature of P. aeruginosa and results from the acquisition of a stable genetic mutation, regardless of the origin of the strain. IMPORTANCE P. aeruginosa is an opportunistic pathogen that thrives in many environments. It poses a significant health concern, notably because this bacterium is the most prevalent pathogen found in the lungs of people with cystic fibrosis. In infected hosts, its persistence is considered related to the emergence of an alternative small-colony-variant (SCV) phenotype. By reporting the distribution of P. aeruginosa SCVs in various nonclinical environments and the involvement of c-di-GMP in SCV emergence from both clinical and environmental strains, this work contributes to understanding a conserved adaptation mechanism used by P. aeruginosa to adapt readily in all environments. Hindering this adaptation strategy could help control persistent infection by P. aeruginosa.
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Shewaramani S, Kassen R. Niche, not phylogeny, governs the response to oxygen availability among diverse Pseudomonas aeruginosa strains. Front Microbiol 2022; 13:953964. [PMID: 36060748 PMCID: PMC9428489 DOI: 10.3389/fmicb.2022.953964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/28/2022] [Indexed: 11/23/2022] Open
Abstract
Pseudomonas aeruginosa, a ubiquitous opportunistic pathogen, is a leading cause of chronic infection of airways in cystic fibrosis (CF) patients. Chronic infections typically arise from colonization by environmental strains, followed by adaptation of P. aeruginosa to the conditions within the CF airway. It has been suggested that oxygen availability can be an important source of selection causing trait changes associated with the transition to chronic infection, but little data exist on the response of P. aeruginosa to varying levels of oxygen. Here, we use a diverse collection of P. aeruginosa strains recovered from both CF patients and environmental sources to evaluate the role of oxygen availability in driving adaptation to the CF lung while also accounting for phylogenetic relatedness. While we can detect a signal of phylogeny in trait responses to oxygen availability, niche of origin is a far stronger predictor. Specifically, strains isolated from the lungs of CF patients are more sensitive to external oxidative stress but more resistant to antibiotics under anoxic conditions. Additionally, many, though not all, patho-adaptive traits we assayed are insensitive to oxygen availability. Our results suggest that inferences about trait expression, especially those associated with the transition to chronic infection, depend on both the available oxygen and niche of origin of the strains being studied.
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Alviz-Gazitua P, González A, Lee MR, Aranda CP. Molecular Relationships in Biofilm Formation and the Biosynthesis of Exoproducts in Pseudoalteromonas spp. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2022; 24:431-447. [PMID: 35486299 DOI: 10.1007/s10126-022-10097-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
Most members of the Pseudoalteromonas genus have been isolated from living surfaces as members of epiphytic and epizooic microbiomes on marine macroorganisms. Commonly Pseudoalteromonas isolates are reported as a source of bioactive exoproducts, i.e., secondary metabolites, such as exopolymeric substances and extracellular enzymes. The experimental conditions for the production of these agents are commonly associated with sessile metabolic states such as biofilms or liquid cultures in the stationary growth phase. Despite this, the molecular mechanisms that connect biofilm formation and the biosynthesis of exoproducts in Pseudoalteromonas isolates have rarely been mentioned in the literature. This review compiles empirical evidence about exoproduct biosynthesis conditions and molecular mechanisms that regulate sessile metabolic states in Pseudoalteromonas species, to provide a comprehensive perspective on the regulatory convergences that generate the recurrent coexistence of both phenomena in this bacterial genus. This synthesis aims to provide perspectives on the extent of this phenomenon for the optimization of bioprospection studies and biotechnology processes based on these bacteria.
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Affiliation(s)
- P Alviz-Gazitua
- Departamento de Ciencias Biológicas y Biodiversidad, Universidad de Los Lagos, Avda. Fuchslocher 1305, P. Box 5290000, Osorno, Chile
| | - A González
- Departamento de Ciencias Biológicas y Biodiversidad, Universidad de Los Lagos, Avda. Fuchslocher 1305, P. Box 5290000, Osorno, Chile
| | - M R Lee
- Centro i~mar, Universidad de Los Lagos, Camino a Chinquihue km 6, P. Box 5480000, Puerto Montt, Chile
| | - C P Aranda
- Departamento de Ciencias Biológicas y Biodiversidad, Universidad de Los Lagos, Avda. Fuchslocher 1305, P. Box 5290000, Osorno, Chile.
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Liu Y, Gloag ES, Hill PJ, Parsek MR, Wozniak DJ. Interbacterial Antagonism Mediated by a Released Polysaccharide. J Bacteriol 2022; 204:e0007622. [PMID: 35446119 PMCID: PMC9112932 DOI: 10.1128/jb.00076-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/06/2022] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa and Staphylococcus aureus are two common pathogens causing chronic infections in the lungs of people with cystic fibrosis (CF) and in wounds, suggesting that these two organisms coexist in vivo. However, P. aeruginosa utilizes various mechanisms to antagonize S. aureus when these organisms are grown together in vitro. Here, we suggest a novel role for Psl in antagonizing S. aureus growth. Psl is an exopolysaccharide that exists in both cell-associated and cell-free forms and is important for biofilm formation in P. aeruginosa. When grown in planktonic coculture with a P. aeruginosa psl mutant, S. aureus had increased survival compared to when it was grown with wild-type P. aeruginosa. We found that cell-free Psl was critical for the killing, as purified cell-free Psl was sufficient to kill S. aureus. Transmission electron microscopy of S. aureus treated with Psl revealed disrupted cell envelopes, suggesting that Psl causes S. aureus cell lysis. This was independent of known mechanisms used by P. aeruginosa to antagonize S. aureus. Cell-free Psl could also promote S. aureus killing during growth in in vivo-like conditions. We also found that Psl production in P. aeruginosa CF clinical isolates positively correlated with the ability to kill S. aureus. This could be a result of P. aeruginosa coevolution with S. aureus in CF lungs. In conclusion, this study defines a novel role for P. aeruginosa Psl in killing S. aureus, potentially impacting the coexistence of these two opportunistic pathogens in vivo. IMPORTANCE Pseudomonas aeruginosa and Staphylococcus aureus are two important opportunistic human pathogens commonly coisolated from clinical samples. However, P. aeruginosa can utilize various mechanisms to antagonize S. aureus in vitro. Here, we investigated the interactions between these two organisms and report a novel role for P. aeruginosa exopolysaccharide Psl in killing S. aureus. We found that cell-free Psl could kill S. aureus in vitro, possibly by inducing cell lysis. This was also observed in conditions reflective of in vivo scenarios. In accord with this, Psl production in P. aeruginosa clinical isolates positively correlated with their ability to kill S. aureus. Together, our data suggest a role for Psl in affecting the coexistence of P. aeruginosa and S. aureus in vivo.
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Affiliation(s)
- Yiwei Liu
- Department of Microbiology, Ohio State University, Columbus, Ohio, USA
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Erin S. Gloag
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Preston J. Hill
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Matthew R. Parsek
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Daniel J. Wozniak
- Department of Microbiology, Ohio State University, Columbus, Ohio, USA
- Department of Microbial Infection and Immunity, Ohio State University College of Medicine, Columbus, Ohio, USA
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9
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Yu Z, Fu Y, Zhang W, Zhu L, Yin W, Chou SH, He J. The RNA Chaperone Protein Hfq Regulates the Characteristic Sporulation and Insecticidal Activity of Bacillus thuringiensis. Front Microbiol 2022; 13:884528. [PMID: 35479624 PMCID: PMC9037596 DOI: 10.3389/fmicb.2022.884528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 03/15/2022] [Indexed: 11/13/2022] Open
Abstract
Bacillus thuringiensis (Bt) is one of the most widely used bio-insecticides at present. It can produce many virulence factors and insecticidal crystal proteins during growth and sporulation. Hfq, on the other hand, is a bacterial RNA chaperone that can regulate the function of different kinds of RNAs, thereby affecting various bacterial phenotypes. To further explore the physiological functions of Hfq in Bt, we took BMB171 as the starting strain, knocked out one, two, or three hfq genes in its genome in different combinations, and compared the phenotypic differences between the deletion mutant strains and the starting strain. We did observe significant changes in several phenotypes, including motility, biofilm formation, sporulation, and insecticidal activity against cotton bollworm, among others. Afterward, we found through transcriptome studies that when all hfq genes were deleted, 32.5% of the genes in Bt were differentially transcribed, with particular changes in the sporulation-related and virulence-related genes. The above data demonstrated that Hfq plays a pivotal role in Bt and can regulate its various physiological functions. Our study on the regulatory mechanism of Hfq in Bt, especially the mining of the regulatory network of its sporulation and insecticidal activity, could lay a theoretical foundation for the better utilization of Bt as an effective insecticide.
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Affiliation(s)
- Zhaoqing Yu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yang Fu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.,National Engineering Research Center of Edible Fungi, Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Wei Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Li Zhu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Wen Yin
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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Franklin T, Wu Y, Lang J, Li S, Yang R. Design of Polymeric Thin Films to Direct Microbial Biofilm Growth, Virulence, and Metabolism. Biomacromolecules 2021; 22:4933-4944. [PMID: 34694768 DOI: 10.1021/acs.biomac.1c00731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Biofilms are ubiquitous in nature, yet strategies to direct biofilm behavior without genetic manipulation are limited. Due to the small selection of materials that have been used to successfully grow biofilms, the availability of functional materials that are able to support growth and program microbial functions remains a critical bottleneck in the design and deployment of functional yet safe microbes. Here, we report the design of insoluble pyridine-rich polymer surfaces synthesized using initiated chemical vapor deposition, which led to modulated biofilm growth and virulence in Pseudomonas aeruginosa (PAO1). A variety of extracellular virulence factors exhibited decreased production in response to the functional polymer, most significantly biomolecules also associated with iron acquisition, validating the material design strategy reported here. This report signifies a rich potential for materials-based strategies to direct the behavior of naturally occurring biofilms, which complement the existing genetic engineering toolkits in advancing microbiology, translational medicine, and biomanufacturing.
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Affiliation(s)
- Trevor Franklin
- Robert F. Smith School of Chemical & Biomolecular Engineering, Cornell University, 120, Olin Hall, Ithaca, New York 14853, United States
| | - Yinan Wu
- Robert F. Smith School of Chemical & Biomolecular Engineering, Cornell University, 120, Olin Hall, Ithaca, New York 14853, United States
| | - Jiayan Lang
- Robert F. Smith School of Chemical & Biomolecular Engineering, Cornell University, 120, Olin Hall, Ithaca, New York 14853, United States
| | - Sijin Li
- Robert F. Smith School of Chemical & Biomolecular Engineering, Cornell University, 120, Olin Hall, Ithaca, New York 14853, United States
| | - Rong Yang
- Robert F. Smith School of Chemical & Biomolecular Engineering, Cornell University, 120, Olin Hall, Ithaca, New York 14853, United States
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11
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Ghirga F, Stefanelli R, Cavinato L, Lo Sciuto A, Corradi S, Quaglio D, Calcaterra A, Casciaro B, Loffredo MR, Cappiello F, Morelli P, Antonelli A, Rossolini GM, Mangoni M, Mancone C, Botta B, Mori M, Ascenzioni F, Imperi F. A novel colistin adjuvant identified by virtual screening for ArnT inhibitors. J Antimicrob Chemother 2021; 75:2564-2572. [PMID: 32514531 PMCID: PMC7443731 DOI: 10.1093/jac/dkaa200] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/31/2020] [Accepted: 04/21/2020] [Indexed: 12/20/2022] Open
Abstract
Background Colistin is a last-resort treatment option for many MDR Gram-negative bacteria. The covalent addition of l-aminoarabinose to the lipid A moiety of LPS is the main colistin resistance mechanism in the human pathogen Pseudomonas aeruginosa. Objectives Identification (by in silico screening of a chemical library) of potential inhibitors of ArnT, which catalyses the last committed step of lipid A aminoarabinosylation, and their validation in vitro as colistin adjuvants. Methods The available ArnT crystal structure was used for a docking-based virtual screening of an in-house library of natural products. The resulting putative ArnT inhibitors were tested in growth inhibition assays using a reference colistin-resistant P. aeruginosa strain. The most promising compound was further characterized for its range of activity, specificity and cytotoxicity. Additionally, the effect of the compound on lipid A aminoarabinosylation was verified by MS analyses of lipid A. Results A putative ArnT inhibitor (BBN149) was discovered by molecular docking and demonstrated to specifically potentiate colistin activity in colistin-resistant P. aeruginosa isolates, without relevant effect on colistin-susceptible strains. BBN149 also showed adjuvant activity against colistin-resistant Klebsiella pneumoniae and low toxicity to bronchial epithelial cells. Lipid A aminoarabinosylation was reduced in BBN149-treated cells, although only partially. Conclusions This study demonstrates that in silico screening targeting ArnT can successfully identify inhibitors of colistin resistance and provides a promising lead compound for the development of colistin adjuvants for the treatment of MDR bacterial infections.
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Affiliation(s)
- Francesca Ghirga
- Center for Life Nano Science@Sapienza, Italian Institute of Technology, Rome, Italy
| | - Roberta Stefanelli
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Laboratory affiliated to Pasteur Italia-Fondazione Cenci Bolognetti, Rome, Italy.,Department of Sciences, 'Department of Excellence 2018 - 2022', Roma Tre University, Rome, Italy
| | - Luca Cavinato
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Laboratory affiliated to Pasteur Italia-Fondazione Cenci Bolognetti, Rome, Italy
| | - Alessandra Lo Sciuto
- Department of Sciences, 'Department of Excellence 2018 - 2022', Roma Tre University, Rome, Italy
| | - Silvia Corradi
- Center for Life Nano Science@Sapienza, Italian Institute of Technology, Rome, Italy.,Department of Chemistry and Technology of Drugs, 'Department of Excellence 2018 - 2022', Sapienza University of Rome, Rome, Italy
| | - Deborah Quaglio
- Department of Chemistry and Technology of Drugs, 'Department of Excellence 2018 - 2022', Sapienza University of Rome, Rome, Italy
| | - Andrea Calcaterra
- Department of Chemistry and Technology of Drugs, 'Department of Excellence 2018 - 2022', Sapienza University of Rome, Rome, Italy
| | - Bruno Casciaro
- Center for Life Nano Science@Sapienza, Italian Institute of Technology, Rome, Italy
| | - Maria Rosa Loffredo
- Department of Biochemical Sciences, Sapienza University of Rome, Laboratory affiliated to Pasteur Italia-Fondazione Cenci Bolognetti, Rome, Italy
| | - Floriana Cappiello
- Department of Biochemical Sciences, Sapienza University of Rome, Laboratory affiliated to Pasteur Italia-Fondazione Cenci Bolognetti, Rome, Italy
| | - Patrizia Morelli
- Microbiology Laboratory, Giannina Gaslini Institute, Genoa, Italy
| | - Alberto Antonelli
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy.,Clinical Microbiology and Virology Unit, Florence Careggi University Hospital, Florence, Italy
| | - Gian Maria Rossolini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy.,Clinical Microbiology and Virology Unit, Florence Careggi University Hospital, Florence, Italy
| | - Marialuisa Mangoni
- Department of Biochemical Sciences, Sapienza University of Rome, Laboratory affiliated to Pasteur Italia-Fondazione Cenci Bolognetti, Rome, Italy
| | - Carmine Mancone
- Department of Molecular Medicine, 'Department of Excellence 2018 - 2022', Sapienza University of Rome, Rome, Italy
| | - Bruno Botta
- Department of Chemistry and Technology of Drugs, 'Department of Excellence 2018 - 2022', Sapienza University of Rome, Rome, Italy
| | - Mattia Mori
- Department of Biotechnology, Chemistry and Pharmacy, 'Department of Excellence 2018 - 2022', University of Siena, Siena, Italy
| | - Fiorentina Ascenzioni
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Laboratory affiliated to Pasteur Italia-Fondazione Cenci Bolognetti, Rome, Italy
| | - Francesco Imperi
- Department of Sciences, 'Department of Excellence 2018 - 2022', Roma Tre University, Rome, Italy
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Abstract
Antimicrobial resistance is a serious medical threat, particularly given the decreasing rate of discovery of new treatments. Although attempts to find new treatments continue, it has become clear that merely discovering new antimicrobials, even if they are new classes, will be insufficient. It is essential that new strategies be aggressively pursued. Toward that end, the search for treatments that can mitigate bacterial virulence and tilt the balance of host-pathogen interactions in favor of the host has become increasingly popular. In this review, we will discuss recent progress in this field, with a special focus on synthetic small molecule antivirulents that have been identified from high-throughput screens and on treatments that are effective against the opportunistic human pathogen Pseudomonas aeruginosa.
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13
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Manniello MD, Moretta A, Salvia R, Scieuzo C, Lucchetti D, Vogel H, Sgambato A, Falabella P. Insect antimicrobial peptides: potential weapons to counteract the antibiotic resistance. Cell Mol Life Sci 2021; 78:4259-4282. [PMID: 33595669 PMCID: PMC8164593 DOI: 10.1007/s00018-021-03784-z] [Citation(s) in RCA: 104] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/19/2021] [Accepted: 01/29/2021] [Indexed: 02/07/2023]
Abstract
Misuse and overuse of antibiotics have contributed in the last decades to a phenomenon known as antibiotic resistance which is currently considered one of the principal threats to global public health by the World Health Organization. The aim to find alternative drugs has been demonstrated as a real challenge. Thanks to their biodiversity, insects represent the largest class of organisms in the animal kingdom. The humoral immune response includes the production of antimicrobial peptides (AMPs) that are released into the insect hemolymph after microbial infection. In this review, we have focused on insect immune responses, particularly on AMP characteristics, their mechanism of action and applications, especially in the biomedical field. Furthermore, we discuss the Toll, Imd, and JAK-STAT pathways that activate genes encoding for the expression of AMPs. Moreover, we focused on strategies to improve insect peptides stability against proteolytic susceptibility such as D-amino acid substitutions, N-terminus modification, cyclization and dimerization.
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Affiliation(s)
- M D Manniello
- Department of Sciences, University of Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy
| | - A Moretta
- Department of Sciences, University of Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy
| | - R Salvia
- Department of Sciences, University of Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy
- Spinoff XFlies S.R.L, University of Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy
| | - C Scieuzo
- Department of Sciences, University of Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy
- Spinoff XFlies S.R.L, University of Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy
| | - D Lucchetti
- Department of Translational Medicine and Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
| | - H Vogel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745, Jena, Germany
| | - A Sgambato
- Department of Translational Medicine and Surgery, Università Cattolica del Sacro Cuore, Rome, Italy
- Centro di Riferimento Oncologico Della Basilicata (IRCCS-CROB), Rionero in Vulture (PZ), Italy
| | - P Falabella
- Department of Sciences, University of Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy.
- Spinoff XFlies S.R.L, University of Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy.
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14
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Elmassry MM, Bisht K, Colmer-Hamood JA, Wakeman CA, San Francisco MJ, Hamood AN. Malonate utilization by Pseudomonas aeruginosa affects quorum-sensing and virulence and leads to formation of mineralized biofilm-like structures. Mol Microbiol 2021; 116:516-537. [PMID: 33892520 DOI: 10.1111/mmi.14729] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/06/2021] [Accepted: 04/16/2021] [Indexed: 01/02/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that uses malonate among its many carbon sources. We recently reported that, when grown in blood from trauma patients, P. aeruginosa expression of malonate utilization genes was upregulated. In this study, we explored the role of malonate utilization and its contribution to P. aeruginosa virulence. We grew P. aeruginosa strain PA14 in M9 minimal medium containing malonate (MM9) or glycerol (GM9) as a sole carbon source and assessed the effect of the growth on quorum sensing, virulence factors, and antibiotic resistance. Growth of PA14 in MM9, compared to GM9, reduced the production of elastases, rhamnolipids, and pyoverdine; enhanced the production of pyocyanin and catalase; and increased its sensitivity to norfloxacin. Growth in MM9 decreased extracellular levels of N-acylhomoserine lactone autoinducers, an effect likely associated with increased pH of the culture medium; but had little effect on extracellular levels of PQS. At 18 hr of growth in MM9, PA14 formed biofilm-like structures or aggregates that were associated with biomineralization, which was related to increased pH of the culture medium. These results suggest that malonate significantly impacts P. aeruginosa pathogenesis by influencing the quorum sensing systems, the production of virulence factors, biofilm formation, and antibiotic resistance.
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Affiliation(s)
- Moamen M Elmassry
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Karishma Bisht
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Jane A Colmer-Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Department of Medical Education, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | | | - Michael J San Francisco
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.,Honors College, Texas Tech University, Lubbock, TX, USA
| | - Abdul N Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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15
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Pyoverdines Are Essential for the Antibacterial Activity of Pseudomonas chlororaphis YL-1 under Low-Iron Conditions. Appl Environ Microbiol 2021; 87:AEM.02840-20. [PMID: 33452032 DOI: 10.1128/aem.02840-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 12/24/2020] [Indexed: 01/23/2023] Open
Abstract
Pseudomonas chlororaphis YL-1 has extensive antimicrobial activities against phytopathogens, and its genome harbors a pyoverdine (PVD) biosynthesis gene cluster. The alternative sigma factor PvdS in Pseudomonas aeruginosa PAO1 acts as a critical regulator in response to iron starvation. The assembly of the PVD backbone starts with peptide synthetase enzyme PvdL. PvdF catalyzes formylation of l-OH-Orn to produce l-N 5-hydroxyornithine. Here, we describe the characterization of PVD production in YL-1 and its antimicrobial activity in comparison with that of its PVD-deficient ΔpvdS, ΔpvdF, and ΔpvdL mutants, which were obtained using a sacB-based site-specific mutagenesis strategy. Using in vitro methods, we examined the effect of exogenous iron under low-iron conditions and an iron-chelating agent under iron-sufficient conditions on PVD production, antibacterial activity, and the relative expression of the PVD transcription factor gene pvdS in YL-1. We found that strain YL-1, the ΔpvdF mutant, and the ΔpvdS(pUCP26-pvdS) complemented strain produced visible PVDs and demonstrated a wide range of inhibitory effects against Gram-negative and Gram-positive bacteria in vitro under low-iron conditions and that with the increase of iron, its PVD production and antibacterial activity were reduced. The antibacterial compounds produced by strain YL-1 under low-iron conditions were PVDs based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Moreover, the antibacterial activity observed in vitro was correlated with in vivo control efficacies of strain YL-1 against rice bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae. Collectively, PVDs are responsible for the antibacterial activities of strain YL-1 under both natural and induced low-iron conditions.IMPORTANCE The results demonstrated that PVDs are essential for the broad-spectrum antibacterial activities of strain YL-1 against both Gram-positive and Gram-negative bacteria under low-iron conditions. Our findings also highlight the effect of exogenous iron on the production of PVD and the importance of this bacterial product in bacterial interactions. As a biocontrol agent, PVDs can directly inhibit the proliferation of the tested bacteria in addition to participating in iron competition.
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16
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Raizman R, Little W, Smith AC. Rapid Diagnosis of Pseudomonas aeruginosa in Wounds with Point-Of-Care Fluorescence Imaing. Diagnostics (Basel) 2021; 11:diagnostics11020280. [PMID: 33670266 PMCID: PMC7917920 DOI: 10.3390/diagnostics11020280] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/06/2021] [Accepted: 02/09/2021] [Indexed: 01/14/2023] Open
Abstract
Pseudomonas aeruginosa (PA) is a common bacterial pathogen in chronic wounds known for its propensity to form biofilms and evade conventional treatment methods. Early detection of PA in wounds is critical to the mitigation of more severe wound outcomes. Point-of-care bacterial fluorescence imaging illuminates wounds with safe, violet light, triggering the production of cyan fluorescence from PA. A prospective single blind clinical study was conducted to determine the positive predictive value (PPV) of cyan fluorescence for the detection of PA in wounds. Bacterial fluorescence using the MolecuLight i:X imaging device revealed cyan fluorescence signal in 28 chronic wounds, including venous leg ulcers, surgical wounds, diabetic foot ulcers and other wound types. To correlate the cyan signal to the presence of PA, wound regions positive for cyan fluorescence were sampled via curettage. A semi-quantitative culture analysis of curettage samples confirmed the presence of PA in 26/28 wounds, resulting in a PPV of 92.9%. The bacterial load of PA from cyan-positive regions ranged from light to heavy. Less than 20% of wounds that were positive for PA exhibited the classic symptoms of PA infection. These findings suggest that cyan detected on fluorescence images can be used to reliably predict bacteria, specifically PA at the point-of-care.
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Affiliation(s)
- Rose Raizman
- Department of Professional Practice, Scarborough Health Network, Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, ON M1E 4B9, Canada
- Correspondence: ; Tel.: +1-416-886-2328
| | - William Little
- Department of Honors Studies, Texas Tech University, Lubbock, TX 79409, USA; (W.L.); (A.C.S.)
| | - Allie Clinton Smith
- Department of Honors Studies, Texas Tech University, Lubbock, TX 79409, USA; (W.L.); (A.C.S.)
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17
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Keown K, Reid A, Moore JE, Taggart CC, Downey DG. Coinfection with Pseudomonas aeruginosa and Aspergillus fumigatus in cystic fibrosis. Eur Respir Rev 2020; 29:29/158/200011. [PMID: 33208485 DOI: 10.1183/16000617.0011-2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/16/2020] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVES Cystic fibrosis (CF) lung disease is characterised by mucus stasis, chronic infection and inflammation, causing progressive structural lung disease and eventual respiratory failure. CF airways are inhabited by an ecologically diverse polymicrobial environment with vast potential for interspecies interactions, which may be a contributing factor to disease progression. Pseudomonas aeruginosa and Aspergillus fumigatus are the most common bacterial and fungal species present in CF airways respectively and coinfection results in a worse disease phenotype. METHODS In this review we examine existing expert knowledge of chronic co-infection with P. aeruginosa and A. fumigatus in CF patients. We summarise the mechanisms of interaction and evaluate the clinical and inflammatory impacts of this co-infection. RESULTS P. aeruginosa inhibits A. fumigatus through multiple mechanisms: phenazine secretion, iron competition, quorum sensing and through diffusible small molecules. A. fumigatus reciprocates inhibition through gliotoxin release and phenotypic adaptations enabling evasion of P. aeruginosa inhibition. Volatile organic compounds secreted by P. aeruginosa stimulate A. fumigatus growth, while A. fumigatus stimulates P. aeruginosa production of cytotoxic elastase. CONCLUSION A complex bi-directional relationship exists between P. aeruginosa and A. fumigatus, exhibiting both mutually antagonistic and cooperative facets. Cross-sectional data indicate a worsened disease state in coinfected patients; however, robust longitudinal studies are required to derive causality and to determine whether interspecies interaction contributes to disease progression.
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Affiliation(s)
- Karen Keown
- Royal Belfast Hospital for Sick Children, Belfast Health and Social Care Trust, Belfast, UK.,Wellcome Wolfson Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - Alastair Reid
- Royal Belfast Hospital for Sick Children, Belfast Health and Social Care Trust, Belfast, UK
| | - John E Moore
- Northern Ireland Public Health Laboratory, Dept of Bacteriology, Belfast City Hospital, Belfast, UK
| | - Clifford C Taggart
- Wellcome Wolfson Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK
| | - Damian G Downey
- Wellcome Wolfson Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK
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18
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Zhang Y, Pan X, Wang L, Chen L. Iron metabolism in Pseudomonas aeruginosa biofilm and the involved iron-targeted anti-biofilm strategies. J Drug Target 2020; 29:249-258. [PMID: 32969723 DOI: 10.1080/1061186x.2020.1824235] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Pseudomonas aeruginosa is a gram-negative bacterium that exists in various ecosystems, causing severe infections in patients with AIDS or cystic fibrosis. P. aeruginosa can form biofilm on a variety of surfaces, whereby the bacteria produce defensive substances and enhance antibiotic-resistance, making themselves more adaptable to hostile environments. P. aeruginosa resistance represents one of the main causes of infection-related morbidity and mortality at a global level. Iron is required for the growth of P. aeruginosa biofilm. This review summarises how the iron metabolism contributes to develop biofilm, and more importantly, it may provide some references for the clinic to achieve novel anti-biofilm therapeutics by targeting iron activities.
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Affiliation(s)
- Yapeng Zhang
- Department of Medical Microbiology, School of Basic Medical Sciences, Central South University, Changsha, China
| | - Xuanhe Pan
- Department of Medical Microbiology, School of Basic Medical Sciences, Central South University, Changsha, China
| | - Linqian Wang
- Department of Clinical Laboratory, Hunan Cancer Hospital, the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, China
| | - Liyu Chen
- Department of Medical Microbiology, School of Basic Medical Sciences, Central South University, Changsha, China
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19
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Martínez-Alemán S, Bustamante A, Jimenez-Valdes R, González G, Sánchez-González A. Pseudomonas aeruginosa isolates from cystic fibrosis patients induce neutrophil extracellular traps with different morphologies that could correlate with their disease severity. Int J Med Microbiol 2020; 310:151451. [DOI: 10.1016/j.ijmm.2020.151451] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 08/19/2020] [Accepted: 08/24/2020] [Indexed: 12/11/2022] Open
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20
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Clinical Significance of Carbapenem-Tolerant Pseudomonas aeruginosa Isolated in the Respiratory Tract. Antibiotics (Basel) 2020; 9:antibiotics9090626. [PMID: 32967210 PMCID: PMC7558279 DOI: 10.3390/antibiotics9090626] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 12/22/2022] Open
Abstract
We often come across difficult to treat infections—even after administering appropriate antibiotics according to the minimal inhibitory concentration of the causative bacteria. Antibiotic tolerance has recently started to garner attention as a crucial mechanism of refractory infections. However, few studies have reported the correlation between clinical outcomes and antibiotic tolerance. This study aims to clarify the effect of antibiotic tolerance on clinical outcomes of respiratory tract infection caused by Pseudomonas aeuginosa (P. aeruginosa). We examined a total of 63 strains isolated from sputum samples of different patients and conducted a retrospective survey with the medical records of 37 patients with imipenem-sensitive P. aeruginosa infections. Among them, we selected 15 patients with respiratory infections, and they were divided into high-tolerance minimal bactericidal concentration for adherent bacteria (MBCAD)/minimal inhibitory concentration for adherent bacteria (MICAD) ≥ 32 (n = 9) group and low-tolerance MBCAD/MICAD ≤ 16 (n = 6) group for further investigations. The findings indicated that the high-tolerance group consisted of many cases requiring hospitalization. Chest computed tomography findings showed that the disease was more extensive in the high-tolerance group compared to the low-tolerance group. Regarding the bacterial phenotypic characterization, the high-tolerance group significantly upregulated the production of the virulence factors compared to the low-tolerance group. Our study provided evidence that carbapenem tolerance level is a potent prognostic marker of P. aeruginosa infections, and carbapenem tolerance could be a potential target for new antimicrobial agents to inhibit the progression of persistent P. aeruginosa infections.
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21
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Lo Sciuto A, Cervoni M, Stefanelli R, Mancone C, Imperi F. Effect of lipid A aminoarabinosylation on Pseudomonas aeruginosa colistin resistance and fitness. Int J Antimicrob Agents 2020; 55:105957. [PMID: 32278012 DOI: 10.1016/j.ijantimicag.2020.105957] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/10/2020] [Accepted: 03/20/2020] [Indexed: 01/06/2023]
Abstract
Colistin represents the last-line treatment option against many multidrug-resistant Gram-negative pathogens. Several lines of evidence indicate that aminoarabinosylation of the lipid A moiety of lipopolysaccharide (LPS) is an essential step for the development of colistin resistance in Pseudomonas aeruginosa. However, whether it is sufficient to confer resistance in this bacterium remains unclear. The aim of this work was to investigate the specific contribution of lipid A aminoarabinosylation to colistin resistance in P. aeruginosa and evaluate the effect of this resistance mechanism on bacterial fitness. Recombinant strains constitutively expressing the enzymes for lipid A aminoarabinosylation were generated in a small collection of reference and clinical isolates and verified by quantitative reverse transcription polymerase chain reaction (qRT-PCR), lipid A extraction and mass spectrometry. The effect of aminoarabinosylated lipid A on colistin resistance was found to be strain- and culture condition-dependent. Higher levels of resistance were generally obtained in the presence of divalent cations, which appear to be important for aminoarabinosylation-mediated colistin resistance. High colistin resistance was also observed for most strains in human serum and in artificial sputum medium, which should partly mimic growth conditions during infection. The results of growth, biofilm, cell envelope integrity and Galleria mellonella infection assays indicate that lipid A aminoarabinosylation does not cause relevant fitness costs in P. aeruginosa.
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Affiliation(s)
| | | | - Roberta Stefanelli
- Department of Science, Roma Tre University, Rome, Italy; Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy
| | - Carmine Mancone
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
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22
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Kang D, Revtovich AV, Chen Q, Shah KN, Cannon CL, Kirienko NV. Pyoverdine-Dependent Virulence of Pseudomonas aeruginosa Isolates From Cystic Fibrosis Patients. Front Microbiol 2019; 10:2048. [PMID: 31551982 PMCID: PMC6743535 DOI: 10.3389/fmicb.2019.02048] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/20/2019] [Indexed: 01/03/2023] Open
Abstract
The development of therapies that modulate or prevent pathogen virulence may be a key strategy for circumventing antimicrobial resistance. Toward that end, we examined the production of pyoverdine, a key virulence determinant, in ∼70 Pseudomonas aeruginosa isolates from pediatric cystic fibrosis patients. Pyoverdine production was heterogeneous and showed a clear correlation with pathogenicity in Caenorhabditis elegans and an acute murine pneumonia model. Examination showed pyoverdine accumulation in host tissues, including extrapharyngeal tissues of C. elegans and lung tissues of mice, where accumulation correlated with host death. Many of the isolates tested were resistant to multiple antimicrobials, so we assayed the ability of pyoverdine inhibitors to mitigate virulence and rescue pyoverdine-mediated host pathology. Representatives from three different classes of pyoverdine inhibitors (gallium, fluoropyrimidines, and LK11) significantly improved survival. Our findings highlight the utility of targeting virulence factors in general, and pyoverdine in particular, as a promising method to control bacterial pathogenesis as the utility of antimicrobials continues to diminish.
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Affiliation(s)
- Donghoon Kang
- Department of BioSciences, Rice University, Houston, TX, United States
| | | | - Qingquan Chen
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, TX, United States
| | - Kush N Shah
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, TX, United States
| | - Carolyn L Cannon
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, TX, United States
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23
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Pseudomonas aeruginosa Keratitis: Protease IV and PASP as Corneal Virulence Mediators. Microorganisms 2019; 7:microorganisms7090281. [PMID: 31443433 PMCID: PMC6780138 DOI: 10.3390/microorganisms7090281] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/12/2019] [Accepted: 08/15/2019] [Indexed: 11/17/2022] Open
Abstract
Pseudomonas aeruginosa is a leading cause of bacterial keratitis, especially in users of contact lenses. These infections are characterized by extensive degradation of the corneal tissue mediated by Pseudomonas protease activities, including both Pseudomonas protease IV (PIV) and the P. aeruginosa small protease (PASP). The virulence role of PIV was determined by the reduced virulence of a PIV-deficient mutant relative to its parent strain and the mutant after genetic complementation (rescue). Additionally, the non-ocular pathogen Pseudomonas putida acquired corneal virulence when it produced active PIV from a plasmid-borne piv gene. The virulence of PIV is not limited to the mammalian cornea, as evidenced by its destruction of respiratory surfactant proteins and the cytokine interleukin-22 (IL-22), the key inducer of anti-bacterial peptides. Furthermore, PIV contributes to the P. aeruginosa infection of both insects and plants. A possible limitation of PIV is its inefficient digestion of collagens; however, PASP, in addition to cleaving multiple soluble proteins, is able to efficiently cleave collagens. A PASP-deficient mutant lacks the corneal virulence of its parent or rescue strain evidencing its contribution to corneal damage, especially epithelial erosion. Pseudomonas-secreted proteases contribute importantly to infections of the cornea, mammalian lung, insects, and plants.
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24
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Hou L, Debru A, Chen Q, Bao Q, Li K. AmrZ Regulates Swarming Motility Through Cyclic di-GMP-Dependent Motility Inhibition and Controlling Pel Polysaccharide Production in Pseudomonas aeruginosa PA14. Front Microbiol 2019; 10:1847. [PMID: 31474950 PMCID: PMC6707383 DOI: 10.3389/fmicb.2019.01847] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 07/26/2019] [Indexed: 11/16/2022] Open
Abstract
Swarming is a surface-associated motile behavior that plays an important role in the rapid spread, colonization, and subsequent establishment of bacterial communities. In Pseudomonas aeruginosa, swarming is dependent upon a functional flagella and aided by the production of biosurfactants. AmrZ, a conserved transcription factor across pseudomonads, has been shown to be a global regulator of multiple genes important for virulence and ecological fitness. In this study, we expand this concept of global control to swarming motility by showing that deletion of amrZ results in a severe defect in swarming, while multicopy expression of this gene stimulates swarming of P. aeruginosa. Mechanistic studies showed that the swarming defect of an amrZ mutant does not involve changes of biosurfactant production but is associated with flagellar malfunction. The ∆amrZ mutant exhibits increased levels of the second messenger cyclic di-GMP (c-di-GMP) compared to the wild-type strain, under swarming conditions. We found that the diguanylate cyclase GcbA was the main contributor to the increased accumulation of c-di-GMP observed in the ∆amrZ mutant and was a strong inhibitor of flagellar-dependent motility. Our results revealed that the GcbA-dependent inhibition of motility required the presence of two c-di-GMP receptors containing a PilZ domain: FlgZ and PA14_56180. Furthermore, the ∆amrZ mutant exhibits enhanced production of Pel polysaccharide. Epistasis analysis revealed that GcbA and the Pel polysaccharide act independently to limit swarming in ΔamrZ. Our results support a role for AmrZ in controlling swarming motility, yet another social behavior besides biofilm formation that is crucial for the ability of P. aeruginosa to colonize a variety of surfaces. The central role of AmrZ in controlling these behaviors makes it a good target for the development of treatments directed to combat P. aeruginosa infections.
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Affiliation(s)
- Lingli Hou
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China.,Scientific Research Center of Wenzhou Medical University, Wenzhou, China
| | - Alexander Debru
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Qianqian Chen
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Qiyu Bao
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
| | - Kewei Li
- Department of Microbiology and Immunology, Key Laboratory of Laboratory Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, China
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25
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Imperi F, Fiscarelli EV, Visaggio D, Leoni L, Visca P. Activity and Impact on Resistance Development of Two Antivirulence Fluoropyrimidine Drugs in Pseudomonas aeruginosa. Front Cell Infect Microbiol 2019; 9:49. [PMID: 30915278 PMCID: PMC6422106 DOI: 10.3389/fcimb.2019.00049] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/15/2019] [Indexed: 12/21/2022] Open
Abstract
The rise in antibiotic resistance among bacterial pathogens has prompted the exploitation of alternative antibacterial strategies, such as antivirulence therapy. By inhibiting virulence traits, antivirulence drugs are expected to lessen pathogenicity without affecting bacterial growth, therefore avoiding the spread of resistance. However, some studies argued against this assumption, and the lack of antivirulence drugs in clinical use hampers the empirical assessment of this concept. Here we compared the mode of action and range of activity of two drugs which have been proposed for repurposing as quorum sensing and pyoverdine inhibitors in the human pathogen Pseudomonas aeruginosa: the anticancer drug 5-fluorouracil (5-FU) and the antimycotic drug 5-fluorocytosine (5-FC), respectively. The effect on bacterial growth, emergence and spread of resistance, and activity against clinical isolates were assessed. Our results confirm that 5-FU has growth inhibitory activity on reference strains and can rapidly select for spontaneous resistant mutants with loss-of-function mutations in the upp gene, responsible for uracil conversion into UMP. These mutants were also insensitive to the anti-pyoverdine effect of 5-FC. Conversely, 5-FC did not cause relevant growth inhibition, likely because of poor enzymatic conversion into 5-FU by cytosine deaminase. However, coculturing experiments showed that 5-FU resistant mutants can outcompete sensitive cells in mixed populations, in the presence of not only 5-FU but also 5-FC. Moreover, we observed that serial passages of wild-type cells in 5-FC-containing medium leads to the appearance and spread of 5-FC insensitive sub-populations of 5-FU resistant cells. The different effect on growth of 5-FU and 5-FC was overall conserved in a large collection of cystic fibrosis (CF) isolates, corresponding to different infection stages and antibiotic resistance profiles, although high variability was observed among strains. Notably, this analysis also revealed a significant number of pyoverdine-deficient isolates, whose proportion apparently increases over the course of the CF infection. This study demonstrates that the efficacy of an antivirulence drug with no apparent effect on growth can be significantly influenced by the emergence of insensitive mutants, and highlights the importance of the assessment of resistance-associated fitness cost and activity on clinical isolates for the development of "resistance-proof" antivirulence drugs.
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Affiliation(s)
- Francesco Imperi
- Department of Science, Roma Tre University, Rome, Italy
- Laboratory affiliated to Istituto Pasteur Italia–Fondazione Cenci Bolognetti, Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | | | | | - Livia Leoni
- Department of Science, Roma Tre University, Rome, Italy
| | - Paolo Visca
- Department of Science, Roma Tre University, Rome, Italy
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26
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Andersen SB, Ghoul M, Marvig RL, Lee ZB, Molin S, Johansen HK, Griffin AS. Privatisation rescues function following loss of cooperation. eLife 2018; 7:38594. [PMID: 30558711 PMCID: PMC6298776 DOI: 10.7554/elife.38594] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 11/17/2018] [Indexed: 12/11/2022] Open
Abstract
A single cheating mutant can lead to the invasion and eventual eradication of cooperation from a population. Consequently, cheat invasion is often considered equal to extinction in empirical and theoretical studies of cooperator-cheat dynamics. But does cheat invasion necessarily equate extinction in nature? By following the social dynamics of iron metabolism in Pseudomonas aeruginosa during cystic fibrosis lung infection, we observed that individuals evolved to replace cooperation with a ‘private’ behaviour. Phenotypic assays showed that cooperative iron acquisition frequently was upregulated early in infection, which, however, increased the risk of cheat invasion. With whole-genome sequencing we showed that if, and only if, cooperative iron acquisition is lost from the population, a private system was upregulated. The benefit of upregulation depended on iron availability. These findings highlight the importance of social dynamics of natural populations and emphasizes the potential impact of past social interaction on the evolution of private traits.
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Affiliation(s)
- Sandra Breum Andersen
- Department of Zoology, University of Oxford, Oxford, United Kingdom.,Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Melanie Ghoul
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Rasmus L Marvig
- Center for Genomic Medicine, Rigshospitalet, Copenhagen, Denmark
| | - Zhuo-Bin Lee
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Søren Molin
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Helle Krogh Johansen
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Zhao J, Yu W. Interaction between Pseudomonas aeruginosa and Aspergillus fumigatus in cystic fibrosis. PeerJ 2018; 6:e5931. [PMID: 30430043 PMCID: PMC6231424 DOI: 10.7717/peerj.5931] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 10/13/2018] [Indexed: 12/13/2022] Open
Abstract
Background Cystic fibrosis (CF) is a disease characterized by chronic airway infection with a high incidence and poor prognosis. Pseudomonas aeruginosa and Aspergillus fumigatus are pathogens commonly found in CF patients. Clinically, these two microorganisms often coexist in the airway of CF patients. Combined infection with P. aeruginosa and A. fumigatus results in worsening lung function and clinical condition. Methods In this review, we focus on the mutual inhibition and promotion mechanisms of P. aeruginosa and A. fumigatus in CF patients. We also summarized the mechanisms of the interaction between these pathogenic microorganisms. Results P. aeruginosa inhibits A. fumigatus growth through the effects of phenazines, the quorum sensing system, iron competition, bacteriophages, and small colony variants. P. aeruginosa induces A. fumigatus growth through volatile organic compounds and subbacteriostatic concentrations of phenazines. A. fumigatus interferes with P. aeruginosa, affecting its metabolic growth via phenazine metabolic transformation, gliotoxin production, and reduced antibiotic sensitivity. Discussion Coexistence of P. aeruginosa and A. fumigatus can lead to both mutual inhibition and promotion. In different stages of CF disease, the interaction between these two pathogenic microorganisms may shift between promotion and inhibition. A discussion of the mechanisms of P. aeruginosa and A. fumigatus interaction can be beneficial for further treatment of CF patients and for improving the prognosis of the disease.
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Affiliation(s)
- Jingming Zhao
- Department of Respiratory Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Wencheng Yu
- Department of Respiratory Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
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28
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Kang D, Kirienko NV. Interdependence between iron acquisition and biofilm formation in Pseudomonas aeruginosa. J Microbiol 2018; 56:449-457. [PMID: 29948830 DOI: 10.1007/s12275-018-8114-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 03/22/2018] [Accepted: 03/22/2018] [Indexed: 11/28/2022]
Abstract
Bacterial biofilms remain a persistent threat to human healthcare due to their role in the development of antimicrobial resistance. To combat multi-drug resistant pathogens, it is crucial to enhance our understanding of not only the regulation of biofilm formation, but also its contribution to bacterial virulence. Iron acquisition lies at the crux of these two subjects. In this review, we discuss the role of iron acquisition in biofilm formation and how hosts impede this mechanism to defend against pathogens. We also discuss recent findings that suggest that biofilm formation can also have the reciprocal effect, influencing siderophore production and iron sequestration.
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Affiliation(s)
- Donghoon Kang
- Department of Biosciences, Rice University, Houston, USA
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Visca P, Imperi F. An essential transcriptional regulator: the case of Pseudomonas aeruginosa Fur. Future Microbiol 2018; 13:853-856. [PMID: 29877110 DOI: 10.2217/fmb-2018-0081] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Paolo Visca
- Department of Science, University "Roma Tre", Rome, Italy
| | - Francesco Imperi
- Department of Biology & Biotechnology Charles Darwin, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy
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30
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Kang D, Turner KE, Kirienko NV. PqsA Promotes Pyoverdine Production via Biofilm Formation. Pathogens 2017; 7:pathogens7010003. [PMID: 29295589 PMCID: PMC5874729 DOI: 10.3390/pathogens7010003] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 12/18/2017] [Accepted: 12/22/2017] [Indexed: 01/03/2023] Open
Abstract
Biofilms create an impermeable barrier against antimicrobial treatment and immune cell access, severely complicating treatment and clearance of nosocomial Pseudomonas aeruginosa infections. We recently reported that biofilm also contributes to pathogen virulence by regulating the production of the siderophore pyoverdine. In this study, we investigated the role of PqsA, a key cell-signaling protein, in this regulatory pathway. We demonstrate that PqsA promotes pyoverdine production in a biofilm-dependent manner. Under nutritionally deficient conditions, where biofilm and pyoverdine are decoupled, PqsA is dispensable for pyoverdine production. Interestingly, although PqsA-dependent pyoverdine production does not rely upon Pseudomonas quinolone signal (PQS) biosynthesis, exogenous PQS can also trigger biofilm-independent production of pyoverdine. Adding PQS rapidly induced planktonic cell aggregation. Moreover, these clumps of cells exhibit strong expression of pyoverdine biosynthetic genes and show substantial production of this siderophore. Finally, we surveyed the relationship between biofilm formation and pyoverdine production in various clinical and environmental isolates of P. aeruginosa to evaluate the clinical significance of targeting biofilm during infections. Our findings implicate PqsA in P. aeruginosa virulence by regulating biofilm formation and pyoverdine production.
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Affiliation(s)
- Donghoon Kang
- Department of Biosciences, Rice University, Houston, TX 77005, USA.
| | - Kelly E Turner
- Department of Biosciences, Rice University, Houston, TX 77005, USA.
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31
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Ferric Uptake Regulator Fur Is Conditionally Essential in Pseudomonas aeruginosa. J Bacteriol 2017; 199:JB.00472-17. [PMID: 28847923 DOI: 10.1128/jb.00472-17] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 08/23/2017] [Indexed: 12/13/2022] Open
Abstract
In Pseudomonas aeruginosa, the ferric uptake regulator (Fur) protein controls both metabolism and virulence in response to iron availability. Differently from other bacteria, attempts to obtain fur deletion mutants of P. aeruginosa failed, leading to the assumption that Fur is an essential protein in this bacterium. By investigating a P. aeruginosa conditional fur mutant, we demonstrate that Fur is not essential for P. aeruginosa growth in liquid media, biofilm formation, and pathogenicity in an insect model of infection. Conversely, Fur is essential for growth on solid media since Fur-depleted cells are severely impaired in colony formation. Transposon-mediated random mutagenesis experiments identified pyochelin siderophore biosynthesis as a major cause of the colony growth defect of the conditional fur mutant, and deletion mutagenesis confirmed this evidence. Impaired colony growth of pyochelin-proficient Fur-depleted cells does not depend on oxidative stress, since Fur-depleted cells do not accumulate higher levels of reactive oxygen species (ROS) and are not rescued by antioxidant agents or overexpression of ROS-detoxifying enzymes. Ectopic expression of pch genes revealed that pyochelin production has no inhibitory effects on a fur deletion mutant of Pseudomonas syringae pv. tabaci, suggesting that the toxicity of the pch locus in Fur-depleted cells involves a P. aeruginosa-specific pathway(s).IMPORTANCE Members of the ferric uptake regulator (Fur) protein family are bacterial transcriptional repressors that control iron uptake and storage in response to iron availability, thereby playing a crucial role in the maintenance of iron homeostasis. While fur null mutants of many bacteria have been obtained, Fur appears to be essential in Pseudomonas aeruginosa for still unknown reasons. We obtained Fur-depleted P. aeruginosa cells by conditional mutagenesis and showed that Fur is dispensable for planktonic growth, while it is required for colony formation. This is because Fur protects P. aeruginosa colonies from toxicity exerted by the pyochelin siderophore. This work provides a functional basis to the essentiality of Fur in P. aeruginosa and highlights unique properties of the Fur regulon in this species.
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Kang D, Kirienko NV. High-Throughput Genetic Screen Reveals that Early Attachment and Biofilm Formation Are Necessary for Full Pyoverdine Production by Pseudomonas aeruginosa. Front Microbiol 2017; 8:1707. [PMID: 28928729 PMCID: PMC5591869 DOI: 10.3389/fmicb.2017.01707] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 08/23/2017] [Indexed: 01/14/2023] Open
Abstract
Pseudomonas aeruginosa is a re-emerging, multidrug-resistant, opportunistic pathogen that threatens the lives of immunocompromised patients, patients with cystic fibrosis, and those in critical care units. One of the most important virulence factors in this pathogen is the siderophore pyoverdine. Pyoverdine serves several critical roles during infection. Due to its extremely high affinity for ferric iron, pyoverdine gives the pathogen a significant advantage over the host in their competition for iron. In addition, pyoverdine can regulate the production of multiple bacterial virulence factors and perturb host mitochondrial homeostasis. Inhibition of pyoverdine biosynthesis decreases P. aeruginosa pathogenicity in multiple host models. To better understand the regulation of pyoverdine production, we developed a high-throughput genetic screen that uses the innate fluorescence of pyoverdine to identify genes necessary for its biosynthesis. A substantial number of hits showing severe impairment of pyoverdine production were in genes responsible for early attachment and biofilm formation. In addition to genetic disruption of biofilm, both physical and chemical perturbations also attenuated pyoverdine production. This regulatory relationship between pyoverdine and biofilm is particularly significant in the context of P. aeruginosa multidrug resistance, where the formation of biofilm is a key mechanism preventing access to antimicrobials and the immune system. Furthermore, we demonstrate that the biofilm inhibitor 2-amino-5,6-dimethylbenzimidazole effectively attenuates pyoverdine production and rescues Caenorhabditis elegans from P. aeruginosa-mediated pathogenesis. Our findings suggest that targeting biofilm formation in P. aeruginosa infections may have multiple therapeutic benefits and that employing an unbiased, systems biology-based approach may be useful for understanding the regulation of specific virulence factors and identifying novel anti-virulence therapeutics or new applications for existing therapies for P. aeruginosa infections.
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Affiliation(s)
- Donghoon Kang
- Department of Biosciences, Rice UniversityHouston, TX, United States
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33
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Anand R, Moss RB, Sass G, Banaei N, Clemons KV, Martinez M, Stevens DA. Small Colony Variants of Pseudomonas aeruginosa Display Heterogeneity in Inhibiting Aspergillus fumigatus Biofilm. Mycopathologia 2017; 183:263-272. [DOI: 10.1007/s11046-017-0186-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/28/2017] [Indexed: 11/25/2022]
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Inhibitors of multidrug efflux pumps of Pseudomonas aeruginosa from natural sources: An in silico high-throughput virtual screening and in vitro validation. Med Chem Res 2016. [DOI: 10.1007/s00044-016-1761-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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35
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Lin CS, Tsai YH, Chang CJ, Tseng SF, Wu TR, Lu CC, Wu TS, Lu JJ, Horng JT, Martel J, Ojcius DM, Lai HC, Young JD. An iron detection system determines bacterial swarming initiation and biofilm formation. Sci Rep 2016; 6:36747. [PMID: 27845335 PMCID: PMC5109203 DOI: 10.1038/srep36747] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/20/2016] [Indexed: 11/30/2022] Open
Abstract
Iron availability affects swarming and biofilm formation in various bacterial species. However, how bacteria sense iron and coordinate swarming and biofilm formation remains unclear. Using Serratia marcescens as a model organism, we identify here a stage-specific iron-regulatory machinery comprising a two-component system (TCS) and the TCS-regulated iron chelator 2-isocyano-6,7-dihydroxycoumarin (ICDH-Coumarin) that directly senses and modulates environmental ferric iron (Fe3+) availability to determine swarming initiation and biofilm formation. We demonstrate that the two-component system RssA-RssB (RssAB) directly senses environmental ferric iron (Fe3+) and transcriptionally modulates biosynthesis of flagella and the iron chelator ICDH-Coumarin whose production requires the pvc cluster. Addition of Fe3+, or loss of ICDH-Coumarin due to pvc deletion results in prolonged RssAB signaling activation, leading to delayed swarming initiation and increased biofilm formation. We further show that ICDH-Coumarin is able to chelate Fe3+ to switch off RssAB signaling, triggering swarming initiation and biofilm reduction. Our findings reveal a novel cellular system that senses iron levels to regulate bacterial surface lifestyle.
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Affiliation(s)
- Chuan-Sheng Lin
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Biochemistry and Molecular Biology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Yu-Huan Tsai
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Chih-Jung Chang
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Shun-Fu Tseng
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Tsung-Ru Wu
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Chia-Chen Lu
- Department of Respiratory Therapy, Fu Jen University, New Taipei City, Taiwan, Republic of China
| | - Ting-Shu Wu
- Department of Internal Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
| | - Jang-Jih Lu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
| | - Jim-Tong Horng
- Department of Biochemistry and Molecular Biology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Jan Martel
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - David M. Ojcius
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, United States of America
| | - Hsin-Chih Lai
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
- Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan, Republic of China
- Graduate Institute of Health Industry Technology, Chang Gung University of Science and Technology, Taoyuan, Taiwan, Republic of China
| | - John D. Young
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Laboratory of Cellular Physiology and Immunology, Rockefeller University, New York, United States of America
- Biochemical Engineering Research Center, Ming Chi University of Technology, New Taipei City, Taiwan, Republic of China
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36
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Role of Iron Uptake Systems in Pseudomonas aeruginosa Virulence and Airway Infection. Infect Immun 2016; 84:2324-2335. [PMID: 27271740 DOI: 10.1128/iai.00098-16] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 05/26/2016] [Indexed: 12/24/2022] Open
Abstract
Pseudomonas aeruginosa is a leading cause of hospital-acquired pneumonia and chronic lung infections in cystic fibrosis patients. Iron is essential for bacterial growth, and P. aeruginosa expresses multiple iron uptake systems, whose role in lung infection deserves further investigation. P. aeruginosa Fe(3+) uptake systems include the pyoverdine and pyochelin siderophores and two systems for heme uptake, all of which are dependent on the TonB energy transducer. P. aeruginosa also has the FeoB transporter for Fe(2+) acquisition. To assess the roles of individual iron uptake systems in P. aeruginosa lung infection, single and double deletion mutants were generated in P. aeruginosa PAO1 and characterized in vitro, using iron-poor media and human serum, and in vivo, using a mouse model of lung infection. The iron uptake-null mutant (tonB1 feoB) and the Fe(3+) transport mutant (tonB1) did not grow aerobically under low-iron conditions and were avirulent in the mouse model. Conversely, the wild type and the feoB, hasR phuR (heme uptake), and pchD (pyochelin) mutants grew in vitro and caused 60 to 90% mortality in mice. The pyoverdine mutant (pvdA) and the siderophore-null mutant (pvdA pchD) grew aerobically in iron-poor media but not in human serum, and they caused low mortality in mice (10 to 20%). To differentiate the roles of pyoverdine in iron uptake and virulence regulation, a pvdA fpvR double mutant defective in pyoverdine production but expressing wild-type levels of pyoverdine-regulated virulence factors was generated. Deletion of fpvR in the pvdA background partially restored the lethal phenotype, indicating that pyoverdine contributes to the pathogenesis of P. aeruginosa lung infection by combining iron transport and virulence-inducing capabilities.
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