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Trottier MC, de Oliveira Pereira T, Groleau MC, Hoffman LR, Dandekar AA, Déziel E. The end of the reign of a "master regulator''? A defect in function of the LasR quorum sensing regulator is a common feature of Pseudomonas aeruginosa isolates. mBio 2024; 15:e0237623. [PMID: 38315035 PMCID: PMC10936206 DOI: 10.1128/mbio.02376-23] [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] [Indexed: 02/07/2024] Open
Abstract
Pseudomonas aeruginosa, a bacterium causing infections in immunocompromised individuals, regulates several of its virulence functions using three interlinked quorum sensing (QS) systems (las, rhl, and pqs). Despite its presumed importance in regulating virulence, dysfunction of the las system regulator LasR occurs frequently in strains isolated from various environments, including clinical infections. This newfound abundance of LasR-defective strains calls into question existing hypotheses regarding their selection. Indeed, current assumptions concerning factors driving the emergence of LasR-deficient isolates and the role of LasR in the QS hierarchy must be reconsidered. Here, we propose that LasR is not the primary master regulator of QS in all P. aeruginosa genetic backgrounds, even though it remains ecologically significant. We also revisit and complement current knowledge on the ecology of LasR-dependent QS in P. aeruginosa, discuss the hypotheses explaining the putative adaptive benefits of selecting against LasR function, and consider the implications of this renewed understanding.
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Affiliation(s)
- Mylène C. Trottier
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, Québec, Canada
| | - Thays de Oliveira Pereira
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, Québec, Canada
| | - Marie-Christine Groleau
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, Québec, Canada
| | - Lucas R. Hoffman
- Departments of Pediatrics and Microbiology, University of Washington, Seattle, Washington, USA
| | - Ajai A. Dandekar
- Departments of Medicine and Microbiology, University of Washington, Seattle, Washington, USA
| | - Eric Déziel
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, Québec, Canada
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2
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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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3
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Keegan NR, Colón Torres NJ, Stringer AM, Prager LI, Brockley MW, McManaman CL, Wade JT, Paczkowski JE. Promoter selectivity of the RhlR quorum-sensing transcription factor receptor in Pseudomonas aeruginosa is coordinated by distinct and overlapping dependencies on C4-homoserine lactone and PqsE. PLoS Genet 2023; 19:e1010900. [PMID: 38064526 PMCID: PMC10732425 DOI: 10.1371/journal.pgen.1010900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 12/20/2023] [Accepted: 11/21/2023] [Indexed: 12/21/2023] Open
Abstract
Quorum sensing is a mechanism of bacterial cell-cell communication that relies on the production and detection of small molecule autoinducers, which facilitate the synchronous expression of genes involved in group behaviors, such as virulence factor production and biofilm formation. The Pseudomonas aeruginosa quorum sensing network consists of multiple interconnected transcriptional regulators, with the transcription factor, RhlR, acting as one of the main drivers of quorum sensing behaviors. RhlR is a LuxR-type transcription factor that regulates its target genes when bound to its cognate autoinducer, C4-homoserine lactone, which is synthesized by RhlI. RhlR function is also regulated by the metallo-β-hydrolase enzyme, PqsE. We recently showed that PqsE binds RhlR to alter its affinity for promoter DNA, a new mechanism of quorum-sensing receptor activation. Here, we perform ChIP-seq analyses of RhlR to map the binding of RhlR across the P. aeruginosa genome, and to determine the impact of C4-homoserine lactone and PqsE on RhlR binding to different sites across the P. aeruginosa genome. We identify 40 RhlR binding sites, all but three of which are associated with genes known to be regulated by RhlR. C4-homoserine lactone is required for maximal binding of RhlR to many of its DNA sites. Moreover, C4-homoserine lactone is required for maximal RhlR-dependent transcription activation from all sites, regardless of whether it impacts RhlR binding to DNA. PqsE is required for maximal binding of RhlR to many DNA sites, with similar effects on RhlR-dependent transcription activation from those sites. However, the effects of PqsE on RhlR specificity are distinct from those of C4-homoserine lactone, and PqsE is sufficient for RhlR binding to some DNA sites in the absence of C4-homoserine lactone. Together, C4-homoserine lactone and PqsE are required for RhlR binding at the large majority of its DNA sites. Thus, our work reveals three distinct modes of activation by RhlR: i) when RhlR is unbound by autoinducer but bound by PqsE, ii) when RhlR is bound by autoinducer but not bound by PqsE, and iii) when RhlR is bound by both autoinducer and PqsE, establishing a stepwise mechanism for the progression of the RhlR-RhlI-PqsE quorum sensing pathway in P. aeruginosa.
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Affiliation(s)
- Nicholas R. Keegan
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, United States of America
| | - Nathalie J. Colón Torres
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Anne M. Stringer
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Lia I. Prager
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biological Sciences, University at Albany, Albany, New York, United States of America
| | - Matthew W. Brockley
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biological Sciences, University at Albany, Albany, New York, United States of America
| | - Charity L. McManaman
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, United States of America
| | - Joseph T. Wade
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, United States of America
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Jon E. Paczkowski
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, New York, United States of America
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
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4
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Hibbert TM, Whiteley M, Renshaw SA, Neill DR, Fothergill JL. Emerging strategies to target virulence in Pseudomonas aeruginosa respiratory infections. Crit Rev Microbiol 2023:1-16. [PMID: 37999716 DOI: 10.1080/1040841x.2023.2285995] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 11/08/2023] [Indexed: 11/25/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that is responsible for infections in people living with chronic respiratory conditions, such as cystic fibrosis (CF) and non-CF bronchiectasis (NCFB). Traditionally, in people with chronic respiratory disorders, P. aeruginosa infection has been managed with a combination of inhaled and intravenous antibiotic therapies. However, due in part to the prolonged use of antibiotics in these people, the emergence of multi-drug resistant P. aeruginosa strains is a growing concern. The development of anti-virulence therapeutics may provide a new means of treating P. aeruginosa lung infections whilst also combatting the AMR crisis, as these agents are presumed to exert reduced pressure for the emergence of drug resistance as compared to antibiotics. However, the pipeline for developing anti-virulence therapeutics is poorly defined, and it is currently unclear as to whether in vivo and in vitro models effectively replicate the complex pulmonary environment sufficiently to enable development and testing of such therapies for future clinical use. Here, we discuss potential targets for P. aeruginosa anti-virulence therapeutics and the effectiveness of the current models used to study them. Focus is given to the difficulty of replicating the virulence gene expression patterns of P. aeruginosa in the CF and NCFB lung under laboratory conditions and to the challenges this poses for anti-virulence therapeutic development.
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Affiliation(s)
- Tegan M Hibbert
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, UK
| | - Marvin Whiteley
- School of Biological Sciences, Georgia Institute of Technology, Centre for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Stephen A Renshaw
- The Bateson Centre and Division of Clinical Medicine, School of Medicine and Population Health, University of Sheffield, Sheffield, UK
| | - Daniel R Neill
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Joanne L Fothergill
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, UK
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Schmidt AK, Schwartzkopf CM, Pourtois JD, Burgener E, Faith DR, Joyce A, Lamma T, Kumar G, Bollyky PL, Secor PR. Targeted deletion of Pf prophages from diverse Pseudomonas aeruginosa isolates impacts quorum sensing and virulence traits. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.19.567716. [PMID: 38014273 PMCID: PMC10680813 DOI: 10.1101/2023.11.19.567716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that commonly causes medical hardware, wound, and respiratory infections. Temperate filamentous Pf phages that infect P. aeruginosa impact numerous bacterial virulence phenotypes. Most work on Pf phages has focused on strain Pf4 and its host P. aeruginosa PAO1. Expanding from Pf4 and PAO1, this study explores diverse Pf strains infecting P. aeruginosa clinical isolates. We describe a simple technique targeting the Pf lysogeny maintenance gene, pflM (PA0718), that enables the effective elimination of Pf prophages from diverse P. aeruginosa hosts. This study also assesses the effects different Pf phages have on host quorum sensing, biofilm formation, virulence factor production, and virulence. Collectively, this research not only introduces a valuable tool for Pf prophage elimination from diverse P. aeruginosa isolates, but also advances our understanding of the complex relationship between P. aeruginosa and filamentous Pf phages.
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Affiliation(s)
- Amelia K. Schmidt
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | | | - Julie D. Pourtois
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Elizabeth Burgener
- Department of Pediatrics, Division of Pulmonology, Children’s Hospital of Los Angeles, University of Southern California, Los Angeles, CA, USA
| | - Dominick R. Faith
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Alex Joyce
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Tyrza Lamma
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Geetha Kumar
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India
| | - Paul L. Bollyky
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Patrick R. Secor
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
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6
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de Oliveira Pereira T, Groleau MC, Déziel E. Surface growth of Pseudomonas aeruginosa reveals a regulatory effect of 3-oxo-C 12-homoserine lactone in the absence of its cognate receptor, LasR. mBio 2023; 14:e0092223. [PMID: 37732738 PMCID: PMC10653899 DOI: 10.1128/mbio.00922-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 07/26/2023] [Indexed: 09/22/2023] Open
Abstract
IMPORTANCE The bacterium Pseudomonas aeruginosa colonizes and thrives in many environments, in which it is typically found in surface-associated polymicrobial communities known as biofilms. Adaptation to this social behavior is aided by quorum sensing (QS), an intercellular communication system pivotal in the expression of social traits. Regardless of its importance in QS regulation, the loss of function of the master regulator LasR is now considered a conserved adaptation of P. aeruginosa, irrespective of the origin of the strains. By investigating the QS circuitry in surface-grown cells, we found an accumulation of QS signal 3-oxo-C12-HSL in the absence of its cognate receptor and activator, LasR. The current understanding of the QS circuit, mostly based on planktonic growing cells, is challenged by investigating the QS circuitry of surface-grown cells. This provides a new perspective on the beneficial aspects that underline the frequency of LasR-deficient isolates.
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Affiliation(s)
- Thays de Oliveira Pereira
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, Québec, Canada
| | - Marie-Christine Groleau
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, Québec, Canada
| | - Eric Déziel
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), Laval, Québec, Canada
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7
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Cramer N, Klockgether J, Tümmler B. Microevolution of Pseudomonas aeruginosa in the airways of people with cystic fibrosis. Curr Opin Immunol 2023; 83:102328. [PMID: 37116385 DOI: 10.1016/j.coi.2023.102328] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 03/26/2023] [Accepted: 03/27/2023] [Indexed: 04/30/2023]
Abstract
The chronic infections of cystic fibrosis (CF) airways with Pseudomonas aeruginosa are a paradigm of how environmental bacteria can conquer, adapt, and persist in an atypical habitat and successfully evade defense mechanisms and chemotherapy in a susceptible host. The within-host evolution of intraclonal diversity has been examined by whole-genome sequencing, phenotyping, and competitive fitness experiments of serial P. aeruginosa isolates collected from CF airways since onset of colonization for a period of up to 40 years. The spectrum of de novo mutations and the adaptation of phenotype and fitness of the bacterial progeny were more influenced by the living conditions in the CF lung than by the clone type of their ancestor and its genetic repertoire.
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Affiliation(s)
- Nina Cramer
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, D-30625 Hannover, Germany
| | - Jens Klockgether
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, D-30625 Hannover, Germany
| | - Burkhard Tümmler
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, D-30625 Hannover, Germany; Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.
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8
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Schwartzkopf CM, Robinson AJ, Ellenbecker M, Faith DR, Schmidt AK, Brooks DM, Lewerke L, Voronina E, Dandekar AA, Secor PR. Tripartite interactions between filamentous Pf4 bacteriophage, Pseudomonas aeruginosa, and bacterivorous nematodes. PLoS Pathog 2023; 19:e1010925. [PMID: 36800381 PMCID: PMC9980816 DOI: 10.1371/journal.ppat.1010925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 03/02/2023] [Accepted: 02/08/2023] [Indexed: 02/18/2023] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa PAO1 is infected by the filamentous bacteriophage Pf4. Pf4 virions promote biofilm formation, protect bacteria from antibiotics, and modulate animal immune responses in ways that promote infection. Furthermore, strains cured of their Pf4 infection (ΔPf4) are less virulent in animal models of infection. Consistently, we find that strain ΔPf4 is less virulent in a Caenorhabditis elegans nematode infection model. However, our data indicate that PQS quorum sensing is activated and production of the pigment pyocyanin, a potent virulence factor, is enhanced in strain ΔPf4. The reduced virulence of ΔPf4 despite high levels of pyocyanin production may be explained by our finding that C. elegans mutants unable to sense bacterial pigments through the aryl hydrocarbon receptor are more susceptible to ΔPf4 infection compared to wild-type C. elegans. Collectively, our data support a model where suppression of quorum-regulated virulence factors by Pf4 allows P. aeruginosa to evade detection by innate host immune responses.
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Affiliation(s)
- Caleb M. Schwartzkopf
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Autumn J. Robinson
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Mary Ellenbecker
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Dominick R. Faith
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Amelia K. Schmidt
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Diane M. Brooks
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Lincoln Lewerke
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Ekaterina Voronina
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Ajai A. Dandekar
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Patrick R. Secor
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
- * E-mail:
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9
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Juhas M. Communication Between Microorganisms. BRIEF LESSONS IN MICROBIOLOGY 2023:27-41. [DOI: 10.1007/978-3-031-29544-7_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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10
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Feathers JR, Richael EK, Simanek KA, Fromme JC, Paczkowski JE. Structure of the RhlR-PqsE complex from Pseudomonas aeruginosa reveals mechanistic insights into quorum-sensing gene regulation. Structure 2022; 30:1626-1636.e4. [PMID: 36379213 PMCID: PMC9722607 DOI: 10.1016/j.str.2022.10.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/26/2022] [Accepted: 10/20/2022] [Indexed: 11/16/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that is responsible for thousands of deaths every year in the United States. P. aeruginosa virulence factor production is mediated by quorum sensing, a mechanism of bacterial cell-cell communication that relies on the production and detection of signal molecules called autoinducers. In P. aeruginosa, the transcription factor receptor RhlR is activated by a RhlI-synthesized autoinducer. We recently showed that RhlR-dependent transcription is enhanced by a physical interaction with the enzyme PqsE via increased affinity of RhlR for promoter DNA. However, the molecular basis for complex formation and how complex formation enhanced RhlR transcriptional activity remained unclear. Here, we report the structure of ligand-bound RhlR in complex with PqsE. Additionally, we determined the structure of the complex bound with DNA, revealing the mechanism by which RhlR-mediated transcription is enhanced by PqsE, thereby establishing the molecular basis for RhlR-dependent virulence factor production in P. aeruginosa.
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Affiliation(s)
- J Ryan Feathers
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Erica K Richael
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Kayla A Simanek
- Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, NY 12201, USA
| | - J Christopher Fromme
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Jon E Paczkowski
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA; Department of Biomedical Sciences, University at Albany, School of Public Health, Albany, NY 12201, USA.
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