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Xia L, Li Y, Wang Y, Zhou H, Dandekar AA, Wang M, Xu F. Quorum-sensing regulation of phenazine production heightens Pseudomonas aeruginosa resistance to ciprofloxacin. Antimicrob Agents Chemother 2024; 68:e0011824. [PMID: 38526048 PMCID: PMC11064481 DOI: 10.1128/aac.00118-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Accepted: 03/07/2024] [Indexed: 03/26/2024] Open
Abstract
Quorum sensing is a type of cell-cell communication that modulates various biological activities of bacteria. Previous studies indicate that quorum sensing contributes to the evolution of bacterial resistance to antibiotics, but the underlying mechanisms are not fully understood. In this study, we grew Pseudomonas aeruginosa in the presence of sub-lethal concentrations of ciprofloxacin, resulting in a large increase in ciprofloxacin minimal inhibitory concentration. We discovered that quorum sensing-mediated phenazine biosynthesis was significantly enhanced in the resistant isolates, where the quinolone circuit was the predominant contributor to this phenomenon. We found that production of pyocyanin changed carbon flux and showed that the effect can be partially inhibited by the addition of pyruvate to cultures. This study illustrates the role of quorum sensing-mediated phenotypic resistance and suggests a strategy for its prevention.
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Affiliation(s)
- Lexin Xia
- Department of Infectious Diseases, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yue Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, Zhejiang, China
| | - Yufan Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, Zhejiang, China
| | - Hui Zhou
- Department of Infectious Diseases, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ajai A. Dandekar
- Department of Microbiology, University of Washington, Seattle, Washington, USA
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Meizhen Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, Zhejiang, China
| | - Feng Xu
- Department of Infectious Diseases, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Kostylev M, Smalley NE, Chao MH, Greenberg EP. Relationship of the transcription factor MexT to quorum sensing and virulence in Pseudomonas aeruginosa. J Bacteriol 2023; 205:e0022623. [PMID: 38032211 PMCID: PMC10729655 DOI: 10.1128/jb.00226-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 11/09/2023] [Indexed: 12/01/2023] Open
Abstract
IMPORTANCE Pseudomonas aeruginosa is an opportunistic bacterial pathogen. Many of its virulence genes are regulated by quorum sensing (QS), a form of cell-to-cell communication. P. aeruginosa QS consists of three interlinked circuits, LasI-R, Rhl-R, and Pseudomonas quinolone signal (PQS). Additionally, its QS system is interconnected with other regulatory networks, which help optimize gene expression under variable conditions. The numbers of genes regulated by QS differ substantially among P. aeruginosa strains. We show that a regulatory factor MexT, which is activated in response to certain antibiotics, downregulates the RhlI-R circuit and in turn measurably lowers virulence in a nematode worm infection model. Our findings help understand how existing and future therapeutic interventions for P. aeruginosa infections may impact this bacterium's gene regulation and physiology.
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Affiliation(s)
- Maxim Kostylev
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Nicole E. Smalley
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Man Hou Chao
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - E. Peter Greenberg
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
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Clarke A, Llabona IM, Khalid N, Hulvey D, Irvin A, Adams N, Heine HS, Eshraghi A. Tolfenpyrad displays Francisella-targeted antibiotic activity that requires an oxidative stress response regulator for sensitivity. Microbiol Spectr 2023; 11:e0271323. [PMID: 37800934 PMCID: PMC10848828 DOI: 10.1128/spectrum.02713-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/05/2023] [Indexed: 10/07/2023] Open
Abstract
IMPORTANCE Francisella species are highly pathogenic bacteria that pose a threat to global health security. These bacteria can be made resistant to antibiotics through facile methods, and we lack a safe and protective vaccine. Given their history of development as bioweapons, new treatment options must be developed to bolster public health preparedness. Here, we report that tolfenpyrad, a pesticide that is currently in use worldwide, effectively inhibits the growth of Francisella. This drug has an extensive history of use and a plethora of safety and toxicity data, making it a good candidate for development as an antibiotic. We identified mutations in Francisella novicida that confer resistance to tolfenpyrad and characterized a transcriptional regulator that is required for sensitivity to both tolfenpyrad and reactive oxygen species.
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Affiliation(s)
- Ashley Clarke
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, Florida, USA
| | - Isabelle M. Llabona
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, Florida, USA
| | - Nimra Khalid
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, Florida, USA
| | - Danielle Hulvey
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, Florida, USA
| | - Alexis Irvin
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, Florida, USA
| | - Nicole Adams
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, Florida, USA
| | - Henry S. Heine
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - Aria Eshraghi
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, Florida, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
- Department of Oral Biology, University of Florida, Gainesville, Florida, USA
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4
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Abisado-Duque RG, Townsend KA, Mckee BM, Woods K, Koirala P, Holder AJ, Craddock VD, Cabeen M, Chandler JR. An Amino Acid Substitution in Elongation Factor EF-G1A Alters the Antibiotic Susceptibility of Pseudomonas aeruginosa LasR-Null Mutants. J Bacteriol 2023; 205:e0011423. [PMID: 37191503 PMCID: PMC10294626 DOI: 10.1128/jb.00114-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 04/22/2023] [Indexed: 05/17/2023] Open
Abstract
The opportunistic bacterium Pseudomonas aeruginosa uses the LasR-I quorum-sensing system to increase resistance to the aminoglycoside antibiotic tobramycin. Paradoxically, lasR-null mutants are commonly isolated from chronic human infections treated with tobramycin, suggesting there may be a mechanism that permits the emergence of lasR-null mutants under tobramycin selection. We hypothesized that some other genetic mutations that emerge in these isolates might modulate the effects of lasR-null mutations on antibiotic resistance. To test this hypothesis, we inactivated lasR in several highly tobramycin-resistant isolates from long-term evolution experiments. In some of these isolates, inactivating lasR further increased resistance, compared with decreasing resistance of the wild-type ancestor. These strain-dependent effects were due to a G61A nucleotide polymorphism in the fusA1 gene encoding amino acid substitution A21T in the translation elongation factor EF-G1A. The EF-G1A mutational effects required the MexXY efflux pump and the MexXY regulator ArmZ. The fusA1 mutation also modulated ΔlasR mutant resistance to two other antibiotics, ciprofloxacin and ceftazidime. Our results identify a gene mutation that can reverse the direction of the antibiotic selection of lasR mutants, a phenomenon known as sign epistasis, and provide a possible explanation for the emergence of lasR-null mutants in clinical isolates. IMPORTANCE One of the most common mutations in Pseudomonas aeruginosa clinical isolates is in the quorum sensing lasR gene. In laboratory strains, lasR disruption decreases resistance to the clinical antibiotic tobramycin. To understand how lasR mutations emerge in tobramycin-treated patients, we mutated lasR in highly tobramycin-resistant laboratory strains and determined the effects on resistance. Disrupting lasR enhanced the resistance of some strains. These strains had a single amino acid substitution in the translation factor EF-G1A. The EF-G1A mutation reversed the selective effects of tobramycin on lasR mutants. These results illustrate how adaptive mutations can lead to the emergence of new traits in a population and are relevant to understanding how genetic diversity contributes to the progression of disease during chronic infections.
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Affiliation(s)
| | - Kade A. Townsend
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Brielle M. Mckee
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Kathryn Woods
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Pratik Koirala
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Alexandra J. Holder
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Vaughn D. Craddock
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Matthew Cabeen
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA
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5
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Zeng X, Zou Y, Zheng J, Qiu S, Liu L, Wei C. Quorum sensing-mediated microbial interactions: Mechanisms, applications, challenges and perspectives. Microbiol Res 2023; 273:127414. [PMID: 37236065 DOI: 10.1016/j.micres.2023.127414] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/05/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023]
Abstract
Microbial community in natural or artificial environments playes critical roles in substance cycles, products synthesis and species evolution. Although microbial community structures have been revealed via culture-dependent and culture-independent approaches, the hidden forces driving the microbial community are rarely systematically discussed. As a mode of cell-to-cell communication that modifies microbial interactions, quorum sensing can regulate biofilm formation, public goods secretion, and antimicrobial substances synthesis, directly or indirectly influencing microbial community to adapt to the changing environment. Therefore, the current review focuses on microbial community in the different habitats from the quorum sensing perspective. Firstly, the definition and classification of quorum sensing were simply introduced. Subsequently, the relationships between quorum sensing and microbial interactions were deeply explored. The latest progressives regarding the applications of quorum sensing in wastewater treatment, human health, food fermentation, and synthetic biology were summarized in detail. Finally, the bottlenecks and outlooks of quorum sensing driving microbial community were adequately discussed. To our knowledge, this current review is the first to reveal the driving force of microbial community from the quorum sensing perspective. Hopefully, this review provides a theoretical basis for developing effective and convenient approaches to control the microbial community with quorum sensing approaches.
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Affiliation(s)
- Xiangyong Zeng
- School of Liquor and Food Engineering, Guizhou University, Guiyang 550025, China; Guizhou Provincial Key Laboratory of Fermentation and Biophomacy, Guizhou University, Guiyang 550025, China.
| | - Yunman Zou
- School of Liquor and Food Engineering, Guizhou University, Guiyang 550025, China; Guizhou Provincial Key Laboratory of Fermentation and Biophomacy, Guizhou University, Guiyang 550025, China
| | - Jia Zheng
- Wuliangye Yibin Co Ltd, No.150 Minjiang West Road, Yibin City 644007, China
| | - Shuyi Qiu
- School of Liquor and Food Engineering, Guizhou University, Guiyang 550025, China; Guizhou Provincial Key Laboratory of Fermentation and Biophomacy, Guizhou University, Guiyang 550025, China
| | - Lanlan Liu
- School of Liquor and Food Engineering, Guizhou University, Guiyang 550025, China; Guizhou Provincial Key Laboratory of Fermentation and Biophomacy, Guizhou University, Guiyang 550025, China
| | - Chaoyang Wei
- School of Liquor and Food Engineering, Guizhou University, Guiyang 550025, China; Guizhou Provincial Key Laboratory of Fermentation and Biophomacy, Guizhou University, Guiyang 550025, China
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Abisado-Duquea RG, McKee BM, Townsend KA, Woods K, Koirala P, Holder AJ, Craddock VD, Cabeen MT, Chandler JR. Tobramycin adaptation alters the antibiotic susceptibility of Pseudomonas aeruginosa quorum sensing-null mutants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.13.523864. [PMID: 36711731 PMCID: PMC9882136 DOI: 10.1101/2023.01.13.523864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The opportunistic bacterium Pseudomonas aeruginosa uses the LasR-I quorum sensing system to increase resistance to the aminioglycoside antibiotic tobramycin. Paradoxically, lasR-null mutants are commonly isolated from chronic human infections treated with tobramycin, suggesting there may be a mechanism allowing the lasR-null mutants to persist under tobramycin selection. We hypothesized that the effects of inactivating lasR on tobramycin resistance might be dependent on the presence or absence of other gene mutations in that strain, a phenomenon known as epistasis. To test this hypothesis, we inactivated lasR in several highly tobramycin-resistant isolates from long-term evolution experiments. We show that the effects of ΔlasR on tobramycin resistance are strain dependent. The effects can be attributed to a point mutation in the gene encoding the translation elongation factor fusA1 (G61A nucleotide substitution), which confers a strong selective advantage to lasR-null PA14 under tobramycin selection. This fusA1 G61A mutation results in increased activity of the MexXY efflux pump and expression of the mexXY regulator ArmZ. The fusA1 mutation can also modulate ΔlasR mutant resistance to two other antibiotics, ciprofloxacin and ceftazidime. Our results demonstrate the importance of epistatic gene interactions on antibiotic susceptibility of lasR-null mutants. These results support of the idea that gene interactions might play a significant role in the evolution of quorum sensing in P. aeruginosa.
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7
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Huang D, Wang Y, Xiao J, Wang Y, Zhu X, Xu B, Wang M. Scavenging of reactive oxygen species effectively reduces Pseudomonas aeruginosa biofilms through disrupting policing. ENVIRONMENTAL RESEARCH 2023; 220:115182. [PMID: 36586713 DOI: 10.1016/j.envres.2022.115182] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 06/17/2023]
Abstract
Biofilm formation is likely to contribute greatly to antibiotic resistance in bacteria and therefore the efficient removal of bacterial biofilms needs addressing urgently. Here, we reported that the supplement of non-inhibitory concentration of N-acetyl-L-cysteine (NAC), a common reactive oxygen species (ROS) scavenger, can significantly reduce the biomass of mature Pseudomonas aeruginosa biofilms (corroborated by crystal violet assay and laser scanning confocal microscopy). 1 mM NAC increased the cheater (ΔlasR mutant) frequency to 89.4 ± 1.5% in the evolved PAO1 after the 15-day treatment. Scavenging of ROS by NAC induced the collapse of P. aeruginosa biofilms, but it did not alter quorum sensing-regulated genes expression (e.g., hcnC and cioAB) and hydrogen cyanide production. The replenishment of public good protease contributed to the recovery of biofilm biomass, indicating the role of disrupting policing in biofilm inhibition. Furthermore, 7 typical ROS scavengers (e.g., superoxide dismutase, catalase and peroxidase, etc.) also effectively inhibited mature P. aeruginosa biofilms. This study demonstrates that scavenging of ROS can promote the selective control of P. aeruginosa biofilms through policing disruption as a targeted biofilm control strategy in complex water environments.
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Affiliation(s)
- Dan Huang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, 310012, China
| | - Yujie Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Junwei Xiao
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Yufan Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Xinyu Zhu
- Eco-Environmental Science Research and Design Institute of Zhejiang Province, Hangzhou, 310007, China
| | - Baile Xu
- Institute of Soil and Water Resources and Environmental Science, College of Environment and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Meizhen Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, 310012, China.
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8
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Mould DL, Stevanovic M, Ashare A, Schultz D, Hogan DA. Metabolic basis for the evolution of a common pathogenic Pseudomonas aeruginosa variant. eLife 2022; 11:e76555. [PMID: 35502894 PMCID: PMC9224983 DOI: 10.7554/elife.76555] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 04/24/2022] [Indexed: 11/21/2022] Open
Abstract
Microbes frequently evolve in reproducible ways. Here, we show that differences in specific metabolic regulation rather than inter-strain interactions explain the frequent presence of lasR loss-of-function (LOF) mutations in the bacterial pathogen Pseudomonas aeruginosa. While LasR contributes to virulence through its role in quorum sensing, lasR mutants have been associated with more severe disease. A model based on the intrinsic growth kinetics for a wild type strain and its LasR- derivative, in combination with an experimental evolution based genetic screen and further genetics analyses, indicated that differences in metabolism were sufficient to explain the rise of these common mutant types. The evolution of LasR- lineages in laboratory and clinical isolates depended on activity of the two-component system CbrAB, which modulates substrate prioritization through the catabolite repression control pathway. LasR- lineages frequently arise in cystic fibrosis lung infections and their detection correlates with disease severity. Our analysis of bronchoalveolar lavage fluid metabolomes identified compounds that negatively correlate with lung function, and we show that these compounds support enhanced growth of LasR- cells in a CbrB-controlled manner. We propose that in vivo metabolomes contribute to pathogen evolution, which may influence the progression of disease and its treatment.
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Affiliation(s)
- Dallas L Mould
- Department of Microbiology and Immunology, Geisel School of Medicine at DartmouthHanoverUnited States
| | - Mirjana Stevanovic
- Department of Microbiology and Immunology, Geisel School of Medicine at DartmouthHanoverUnited States
| | - Alix Ashare
- Department of Microbiology and Immunology, Geisel School of Medicine at DartmouthHanoverUnited States
- Department of Medicine, Dartmouth-Hitchock Medical CenterLebanonUnited States
| | - Daniel Schultz
- Department of Microbiology and Immunology, Geisel School of Medicine at DartmouthHanoverUnited States
| | - Deborah A Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at DartmouthHanoverUnited States
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Li Y, Xia L, Chen J, Lian Y, Dandekar AA, Xu F, Wang M. Resistance elicited by sub-lethal concentrations of ampicillin is partially mediated by quorum sensing in Pseudomonas aeruginosa. ENVIRONMENT INTERNATIONAL 2021; 156:106619. [PMID: 33989839 DOI: 10.1016/j.envint.2021.106619] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 06/12/2023]
Abstract
The rapid increase of antibiotic resistance is a serious challenge around the world. Antibiotics are present in various environments at sub-lethal concentrations, but how resistance emerges under sub-lethal conditions is not fully clear. In this study, we evolved Pseudomonas aeruginosa PAO1 under sub-lethal conditions, in the presence of either 15-30 μg/mL or 150-300 μg/mL of ampicillin. We found a ~ 5-6 fold increase in the minimum inhibitory concentration (MIC) among evolved isolates exposed to 15-30 μg/mL of ampicillin, and more than a 19-fold of increase in 150-300 μg/mL of ampicillin exposure. DNA sequencing revealed that mpl and ampD were frequently mutated in these resistant strains. We performed a transcriptome analysis of deletion mutations of mpl or ampD, compared to PAO1. Both showed a two-fold increase in expression of quorum sensing (QS) genes including lasR and rhlI/R; the heightened expression was positively correlated with the expression of the ampicillin resistance gene ampC. We queried if quorum sensing contributes to the increase in the ampicillin MIC. After adding the quorum quencher acylase I, the growth yield both decreased by roughly 50% for Δmpl in 2000 μg/mL of ampicillin and ΔampD in 4000 μg/mL of ampicillin. Addition of the QS signals into synthase mutants restored the higher MIC, but only for the rhlI/R circuit. This study highlights the involvement of QS in antibiotic resistance evolution, and shows the multifactorial contributors to the observed phenotypes.
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Affiliation(s)
- Yue Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China
| | - Lexin Xia
- Department of Infectious Diseases, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China
| | - Jian Chen
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China
| | - Yulu Lian
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China
| | - Ajai A Dandekar
- Department of Medicine, University of Washington, Seattle, WA 98195, USA; Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Feng Xu
- Department of Infectious Diseases, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China
| | - Meizhen Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, China.
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10
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Zhou H, Gebhardt MJ, Czyz DM, Yao Y, Shuman HA. The gigA/gigB Genes Regulate the Growth, Stress Response, and Virulence of Acinetobacter baumannii ATCC 17978 Strain. Front Microbiol 2021; 12:723949. [PMID: 34421881 PMCID: PMC8371402 DOI: 10.3389/fmicb.2021.723949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 07/16/2021] [Indexed: 12/03/2022] Open
Abstract
Acinetobacter baumannii is an important pathogen of nosocomial infection. Recently, a group of genes, named “gig” (for Growth in Galleria), have been identified in a contemporary multi-drug resistant clinical isolate of A. baumannii—strain AB5075. Among these so-called gig genes, gigA and gigB were found to promote antibiotic resistance, stress survival, and virulence of AB5075 by interacting with the nitrogen phosphotransferase system (PTSNtr). This study aimed to investigate the roles of gigA/gigB, which appear to comprise a stress-signaling pathway (encoding for an atypical two-component system response regulator and a predicted anti-anti-sigma factor, respectively), and the involvement of ptsP (encoding the Enzyme I component of the PTSNtr) in the growth, stress resistance, and virulence of the widely studied A. baumannii strain ATCC 17978. Genetic analyses of strains harboring mutations of gigA and gigB were performed to investigate the roles of these genes in bacterial growth, stress resistance, evading macrophage defense, and killing of Galleria mellonella larva. In contrast with findings from strain AB5075 where gigA and gigB contribute to aminoglycoside resistance, the data presented herein indicate that the loss of gigA/gigB does not impact antibiotic resistance of strain ATCC 17978. Interestingly, however, we found that deletion of gigA/gigB in the ATCC 17978 background imparts a general growth in laboratory medium and also conferred growth and replication defects within murine macrophages and an inability to kill G. mellonella larvae. Importantly, studies as well as the loss of ptsP restored the phenotypes of the gigA/gigB mutant to that of the wild-type. The data presented herein indicate that in A. baumannii ATCC 17978, the gigA/gigB genes play a key role in both growth and virulence traits, but are dispensable for other stress-resistance survival phenotypes, including aminoglycoside resistance. Our findings thus highlight several similarities and also important differences between the gigA/gigB stress-signaling pathway in two commonly studied isolates of this troublesome pathogen.
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Affiliation(s)
- Hua Zhou
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Department of Microbiology, University of Chicago, Chicago, IL, United States
| | - Michael J Gebhardt
- Department of Microbiology, University of Chicago, Chicago, IL, United States
| | - Daniel M Czyz
- Department of Microbiology, University of Chicago, Chicago, IL, United States.,Department of Microbiology and Cell Science, University of Florida, Gainesville, FL, United States
| | - Yake Yao
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Howard A Shuman
- Department of Microbiology, University of Chicago, Chicago, IL, United States
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