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Girma A. Staphylococcus aureus: Current perspectives on molecular pathogenesis and virulence. Cell Surf 2025; 13:100137. [PMID: 39758277 PMCID: PMC11699754 DOI: 10.1016/j.tcsw.2024.100137] [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: 11/07/2024] [Revised: 12/04/2024] [Accepted: 12/07/2024] [Indexed: 01/07/2025] Open
Abstract
Staphylococcus aureus has evolved a sophisticated regulatory system to control its virulence. One of the main roles of this interconnected network is to sense and respond to diverse environmental signals by altering the synthesis of virulence components required for survival in the host, including cell surface adhesins, extracellular enzymes and toxins. The accessory gene regulator (agr), a quorum sensing system that detects the local concentration of a cyclic peptide signaling molecule, is one of the well-studied of these S. aureus regulatory mechanisms. By using this system, S. aureus is able to sense its own population density and translate this information into a specific pattern of gene expression. In addition to Agr, this pathogen senses specific stimuli through various two-component systems and synchronizes responses with alternative sigma factors and cytoplasmic regulators of the SarA protein family. These different regulatory mechanisms combine host and environmental information into a network that guarantees the best possible response of pathogens to changing circumstances. In this article, an overview of the most significant and thoroughly studied regulatory systems of S. aureus is provided, along with a summary of their roles in host interactions.
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Affiliation(s)
- Abayeneh Girma
- Department of Biology, College of Natural and Computational Science, Mekdela Amba University, P.O. Box 32, Tulu Awuliya, Ethiopia
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2
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Ingmer H, Leisner JJ, Fulaz S. Forssman and the staphylococcal hemolysins. APMIS 2025; 133:e13459. [PMID: 39188243 PMCID: PMC11669744 DOI: 10.1111/apm.13459] [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: 06/12/2024] [Accepted: 08/05/2024] [Indexed: 08/28/2024]
Abstract
Forssman was a Swedish pathologist and microbiologist who, in the 1920s and 1930s conducted a long series of experiments that led to unique insights into surface antigens of blood cells, as well as added to the discrimination of toxins produced by staphylococci that lyse red blood cells. This review takes offset in the studies published by Forssman in APMIS addressing the hemolytic properties of staphylococcal toxins displayed against erythrocytes of animal and human origin. In light of current knowledge, we will discuss the insights we now have and how they may pave the way for curing infections with pathogenic staphylococci, including Staphylococcus aureus.
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Affiliation(s)
- Hanne Ingmer
- Department of Veterinary and Animal ScienceUniversity of CopenhagenCopenhagenDenmark
| | - Jørgen J. Leisner
- Department of Veterinary and Animal ScienceUniversity of CopenhagenCopenhagenDenmark
| | - Stephanie Fulaz
- Department of Veterinary and Animal ScienceUniversity of CopenhagenCopenhagenDenmark
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3
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Podkowik M, Perault AI, Putzel G, Pountain A, Kim J, DuMont AL, Zwack EE, Ulrich RJ, Karagounis TK, Zhou C, Haag AF, Shenderovich J, Wasserman GA, Kwon J, Chen J, Richardson AR, Weiser JN, Nowosad CR, Lun DS, Parker D, Pironti A, Zhao X, Drlica K, Yanai I, Torres VJ, Shopsin B. Quorum-sensing agr system of Staphylococcus aureus primes gene expression for protection from lethal oxidative stress. eLife 2024; 12:RP89098. [PMID: 38687677 PMCID: PMC11060713 DOI: 10.7554/elife.89098] [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: 05/02/2024] Open
Abstract
The agr quorum-sensing system links Staphylococcus aureus metabolism to virulence, in part by increasing bacterial survival during exposure to lethal concentrations of H2O2, a crucial host defense against S. aureus. We now report that protection by agr surprisingly extends beyond post-exponential growth to the exit from stationary phase when the agr system is no longer turned on. Thus, agr can be considered a constitutive protective factor. Deletion of agr resulted in decreased ATP levels and growth, despite increased rates of respiration or fermentation at appropriate oxygen tensions, suggesting that Δagr cells undergo a shift towards a hyperactive metabolic state in response to diminished metabolic efficiency. As expected from increased respiratory gene expression, reactive oxygen species (ROS) accumulated more in the agr mutant than in wild-type cells, thereby explaining elevated susceptibility of Δagr strains to lethal H2O2 doses. Increased survival of wild-type agr cells during H2O2 exposure required sodA, which detoxifies superoxide. Additionally, pretreatment of S. aureus with respiration-reducing menadione protected Δagr cells from killing by H2O2. Thus, genetic deletion and pharmacologic experiments indicate that agr helps control endogenous ROS, thereby providing resilience against exogenous ROS. The long-lived 'memory' of agr-mediated protection, which is uncoupled from agr activation kinetics, increased hematogenous dissemination to certain tissues during sepsis in ROS-producing, wild-type mice but not ROS-deficient (Cybb-/-) mice. These results demonstrate the importance of protection that anticipates impending ROS-mediated immune attack. The ubiquity of quorum sensing suggests that it protects many bacterial species from oxidative damage.
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Affiliation(s)
- Magdalena Podkowik
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of MedicineNew YorkUnited States
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
| | - Andrew I Perault
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
- Department of Microbiology, NYU Grossman School of MedicineNew YorkUnited States
| | - Gregory Putzel
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
- Department of Microbiology, NYU Grossman School of MedicineNew YorkUnited States
- Microbial Computational Genomic Core Lab, NYU Grossman School of MedicineNew YorkUnited States
| | - Andrew Pountain
- Institute for Systems Genetics; NYU Grossman School of MedicineNew YorkUnited States
| | - Jisun Kim
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical SchoolNewarkUnited States
| | - Ashley L DuMont
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of MedicineNew YorkUnited States
| | - Erin E Zwack
- Department of Microbiology, NYU Grossman School of MedicineNew YorkUnited States
| | - Robert J Ulrich
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of MedicineNew YorkUnited States
| | - Theodora K Karagounis
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
- Ronald O. Perelman Department of Dermatology; NYU Grossman School of MedicineNew YorkUnited States
| | - Chunyi Zhou
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of MedicineNew YorkUnited States
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
| | - Andreas F Haag
- School of Medicine, University of St AndrewsSt AndrewsUnited Kingdom
| | - Julia Shenderovich
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
- Department of Microbiology, NYU Grossman School of MedicineNew YorkUnited States
| | - Gregory A Wasserman
- Department of Surgery, Northwell Health Lenox Hill HospitalNew YorkUnited States
| | - Junbeom Kwon
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of MedicineNew YorkUnited States
| | - John Chen
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
| | - Anthony R Richardson
- Department of Microbiology and Molecular Genetics, University of PittsburghPittsburghUnited States
| | - Jeffrey N Weiser
- Department of Microbiology, NYU Grossman School of MedicineNew YorkUnited States
| | - Carla R Nowosad
- Department of Pathology, NYU Grossman School of MedicineNew YorkUnited States
| | - Desmond S Lun
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers UniversityCamdenUnited States
| | - Dane Parker
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical SchoolNewarkUnited States
| | - Alejandro Pironti
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
- Department of Microbiology, NYU Grossman School of MedicineNew YorkUnited States
- Microbial Computational Genomic Core Lab, NYU Grossman School of MedicineNew YorkUnited States
| | - Xilin Zhao
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen UniversityXiamenChina
| | - Karl Drlica
- Public Health Research Institute, New Jersey Medical School, Rutgers UniversityNew YprkUnited States
- Department of Microbiology, Biochemistry & Molecular Genetics, New Jersey Medical School, Rutgers UniversityNewarkUnited States
| | - Itai Yanai
- Institute for Systems Genetics; NYU Grossman School of MedicineNew YorkUnited States
- Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of MedicineNew YorkUnited States
| | - Victor J Torres
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
- Department of Microbiology, NYU Grossman School of MedicineNew YorkUnited States
| | - Bo Shopsin
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of MedicineNew YorkUnited States
- Antimicrobial-Resistant Pathogens Program, New York University School of MedicineNew YorkUnited States
- Department of Microbiology, NYU Grossman School of MedicineNew YorkUnited States
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4
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Podkowik M, Perault AI, Putzel G, Pountain A, Kim J, Dumont A, Zwack E, Ulrich RJ, Karagounis TK, Zhou C, Haag AF, Shenderovich J, Wasserman GA, Kwon J, Chen J, Richardson AR, Weiser JN, Nowosad CR, Lun DS, Parker D, Pironti A, Zhao X, Drlica K, Yanai I, Torres VJ, Shopsin B. Quorum-sensing agr system of Staphylococcus aureus primes gene expression for protection from lethal oxidative stress. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.08.544038. [PMID: 37333372 PMCID: PMC10274873 DOI: 10.1101/2023.06.08.544038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The agr quorum-sensing system links Staphylococcus aureus metabolism to virulence, in part by increasing bacterial survival during exposure to lethal concentrations of H2O2, a crucial host defense against S. aureus. We now report that protection by agr surprisingly extends beyond post-exponential growth to the exit from stationary phase when the agr system is no longer turned on. Thus, agr can be considered a constitutive protective factor. Deletion of agr increased both respiration and fermentation but decreased ATP levels and growth, suggesting that Δagr cells assume a hyperactive metabolic state in response to reduced metabolic efficiency. As expected from increased respiratory gene expression, reactive oxygen species (ROS) accumulated more in the agr mutant than in wild-type cells, thereby explaining elevated susceptibility of Δagr strains to lethal H2O2 doses. Increased survival of wild-type agr cells during H2O2 exposure required sodA, which detoxifies superoxide. Additionally, pretreatment of S. aureus with respiration-reducing menadione protected Δagr cells from killing by H2O2. Thus, genetic deletion and pharmacologic experiments indicate that agr helps control endogenous ROS, thereby providing resilience against exogenous ROS. The long-lived "memory" of agr-mediated protection, which is uncoupled from agr activation kinetics, increased hematogenous dissemination to certain tissues during sepsis in ROS-producing, wild-type mice but not ROS-deficient (Nox2-/-) mice. These results demonstrate the importance of protection that anticipates impending ROS-mediated immune attack. The ubiquity of quorum sensing suggests that it protects many bacterial species from oxidative damage.
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Affiliation(s)
- Magdalena Podkowik
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of Medicine, New York, NY, USA
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
| | - Andrew I. Perault
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
| | - Gregory Putzel
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
- Microbial Computational Genomic Core Lab, NYU Grossman School of Medicine, New York, NY, USA
| | - Andrew Pountain
- Institute for Systems Genetics; NYU Grossman School of Medicine, New York, NY, USA
| | - Jisun Kim
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School Cancer Center, Newark, NJ, USA
| | - Ashley Dumont
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
| | - Erin Zwack
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
| | - Robert J. Ulrich
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of Medicine, New York, NY, USA
| | - Theodora K. Karagounis
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
- Ronald O. Perelman Department of Dermatology; NYU Grossman School of Medicine, New York, NY, USA
| | - Chunyi Zhou
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of Medicine, New York, NY, USA
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
| | - Andreas F. Haag
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Julia Shenderovich
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
| | | | - Junbeom Kwon
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of Medicine, New York, NY, USA
| | - John Chen
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Anthony R. Richardson
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jeffrey N. Weiser
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
| | - Carla R. Nowosad
- Department of Pathology, NYU Grossman School of Medicine, New York, NY, USA
| | - Desmond S. Lun
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers University, Camden, NJ, USA
| | - Dane Parker
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School Cancer Center, Newark, NJ, USA
| | - Alejandro Pironti
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
- Microbial Computational Genomic Core Lab, NYU Grossman School of Medicine, New York, NY, USA
| | - Xilin Zhao
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, Fujian Province, China
| | - Karl Drlica
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, USA
- Department of Microbiology, Biochemistry & Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Itai Yanai
- Institute for Systems Genetics; NYU Grossman School of Medicine, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, USA
| | - Victor J. Torres
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
| | - Bo Shopsin
- Department of Medicine, Division of Infectious Diseases, NYU Grossman School of Medicine, New York, NY, USA
- Antimicrobial-Resistant Pathogens Program, New York University School of Medicine, New York, NY, USA
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, USA
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5
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Tao Z, Ke K, Shi D, Zhu L. Development of a dual fluorescent reporter system to identify inhibitors of Staphylococcus aureus virulence factors. Appl Environ Microbiol 2023; 89:e0097823. [PMID: 37889047 PMCID: PMC10686081 DOI: 10.1128/aem.00978-23] [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: 06/16/2023] [Accepted: 09/15/2023] [Indexed: 10/28/2023] Open
Abstract
IMPORTANCE Staphylococcus aureus is a formidable pathogen responsible for a wide range of infections, and the emergence of antibiotic-resistant strains has posed significant challenges in treating these infections. In this study, we have established a novel dual reporter system capable of concurrently monitoring the activities of two critical virulence regulators in S. aureus. By incorporating both reporters into a single screening platform, we provide a time- and cost-efficient approach for assessing the activity of compounds against two distinct targets in a single screening round. This innovative dual reporter system presents a promising strategy for the identification of molecules capable of modulating virulence gene expression in S. aureus, potentially expediting the development of antivirulence therapies.
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Affiliation(s)
- Zhanhua Tao
- Institute of Eco-Environmental Research, Guangxi Academy of Sciences, Nanning, China
- Guangxi Key Laboratory of Marine Natural Products and Combinatorial Biosynthesis Chemistry, Nanning, China
| | - Ke Ke
- Guangxi Academy of Sciences, Nanning, China
| | | | - Libo Zhu
- Guangxi Academy of Sciences, Nanning, China
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6
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Williams P, Hill P, Bonev B, Chan WC. Quorum-sensing, intra- and inter-species competition in the staphylococci. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001381. [PMID: 37578829 PMCID: PMC10482373 DOI: 10.1099/mic.0.001381] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/31/2023] [Indexed: 08/15/2023]
Abstract
In Gram-positive bacteria such as Staphylococcus aureus and the coagulase-negative staphylococci (CoNS), the accessory gene regulator (agr) is a highly conserved but polymorphic quorum-sensing system involved in colonization, virulence and biofilm development. Signalling via agr depends on the interaction of an autoinducing peptide (AIP) with AgrC, a transmembrane sensor kinase that, once phosphorylated activates the response regulator AgrA. This in turn autoinduces AIP biosynthesis and drives target gene expression directly via AgrA or via the post-transcriptional regulator, RNAIII. In this review we describe the molecular mechanisms underlying the agr-mediated generation of, and response to, AIPs and the molecular basis of AIP-dependent activation and inhibition of AgrC. How the environment impacts on agr functionality is considered and the consequences of agr dysfunction for infection explored. We also discuss the concept of AIP-driven competitive interference between S. aureus and the CoNS and its anti-infective potential.
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Affiliation(s)
- Paul Williams
- Biodiscovery Institute and School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Phil Hill
- School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
| | - Boyan Bonev
- Biodiscovery Institute and School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Weng C. Chan
- School of Pharmacy, Biodiscovery Institute, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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7
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Mauritzen JJ, Søndberg E, Kalatzis PG, Roager L, Gram L, Svenningsen SL, Middelboe M. Strain-specific quorum-sensing responses determine virulence properties in Vibrio anguillarum. Environ Microbiol 2023; 25:1344-1362. [PMID: 36807464 DOI: 10.1111/1462-2920.16356] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/16/2023] [Indexed: 02/23/2023]
Abstract
Bacterial populations communicate using quorum-sensing (QS) molecules and switch on QS regulation to engage in coordinated behaviour such as biofilm formation or virulence. The marine fish pathogen Vibrio anguillarum harbours several QS systems, and our understanding of its QS regulation is still fragmentary. Here, we identify the VanT-QS regulon and explore the diversity and trajectory of traits under QS regulation in Vibrio anguillarum through comparative transcriptomics of two wildtype strains and their corresponding mutants artificially locked in QS-on (ΔvanO) or QS-off (ΔvanT) states. Intriguingly, the two wildtype populations showed different QS responses to cell density changes and operated primarily in the QS-on and QS-off spectrum, respectively. Examining 27 V. anguillarum strains revealed that ~11% were QS-negative, and GFP-reporter measurements of nine QS-positive strains revealed a highly strain-specific nature of the QS responses. We showed that QS controls a plethora of genes involved in processes such as central metabolism, biofilm formation, competence, T6SS, and virulence properties in V. anguillarum, with large strain-specific differences. Moreover, we demonstrated that the QS state is an important driver of virulence towards fish larvae in one of two V. anguillarum strains. We speculate that infections by mixed-strain communities spanning diverse QS strategies optimize the infection efficiency of the pathogen.
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Affiliation(s)
- Jesper Juel Mauritzen
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Emilie Søndberg
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Panos G Kalatzis
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Line Roager
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lone Gram
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Sine Lo Svenningsen
- Section for Biomolecular Sciences, Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - Mathias Middelboe
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
- Department of Biology, University of Southern Denmark, Odense, Denmark
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8
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Polaske TJ, West KHJ, Zhao K, Widner DL, York JT, Blackwell HE. Chemical and biomolecular insights into the Staphylococcus aureus agr quorum sensing system: Current progress and ongoing challenges. Isr J Chem 2023; 63:e202200096. [PMID: 38765792 PMCID: PMC11101167 DOI: 10.1002/ijch.202200096] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Indexed: 03/19/2023]
Abstract
Staphylococcus aureus is a ubiquitous bacterium that has become a major threat to human health due to its extensive toxin production and tremendous capacity for antibiotic resistance (e.g., MRSA "superbug" infections). Amid a worsening antibiotic resistance crisis, new strategies to combat this deadly microbe that remove the selective pressure of traditional approaches are in high demand. S. aureus utilizes an accessory gene regulator (agr) quorum sensing network to monitor its local cellular population and trigger a devastating communal attack, like an invading horde, once a threshold cell density has been reached. The role of the agr system in a range of disease types is still being unraveled. Herein, we discuss the present-day biochemical understanding of agr along with unresolved details, describe its connection to the progression of infection, and review how chemical strategies have been implemented to study and intercept this signaling pathway. This research is illuminating the potential of agr as an anti-virulence target in S. aureus and should inform the study of similar, yet less studied, agr systems in related bacterial pathogens.
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Affiliation(s)
- Thomas J. Polaske
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Korbin H. J. West
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Ke Zhao
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Danielle L. Widner
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Jordan T. York
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Helen E. Blackwell
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
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9
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Characterization of MroQ-Dependent Maturation and Export of the Staphylococcus aureus Accessory Gene Regulatory System Autoinducing Peptide. Infect Immun 2022; 90:e0026322. [PMID: 36073934 PMCID: PMC9584314 DOI: 10.1128/iai.00263-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Gram-positive bacteria produce small autoinducing peptides (AIPs), which act to regulate expression of genes that promote adaptive traits, including virulence. The Gram-positive pathogen Staphylococcus aureus generates a cyclic AIP that controls expression of virulence factors via the accessory gene regulatory (Agr) system. S. aureus strains belong to one of four Agr groups (Agr-I, -II, -III, and -IV); each group harbors allelic variants of AgrD, the precursor of AIP. In a prior screen for S. aureus virulence factors, we identified MroQ, a putative peptidase. A ΔmroQ mutant closely resembled a Δagr mutant and had significant defects in AIP production in an Agr-I strain. Here, we show that expression of AgrD-I in a ΔmroQ mutant leads to accumulation of an AIP processing intermediate at the membrane that coincides with a loss of secreted mature AIP, indicating that MroQ promotes maturation of AgrD-I. MroQ is conserved in all Agr sequence variants, suggesting either identical function among all Agr types or activity specific to Agr-I strains. Our data indicate that MroQ is required for AIP maturation and activity in Agr-I, -II, and -IV strains irrespective of background. However, MroQ is not required for Agr-III activity despite an identifiable role in peptide maturation. Isogenic Δagr and Δagr ΔmroQ strains complemented with Agr-I to -IV validated the critical role of MroQ in the generation of active AIP-I, -II, and -IV but not AIP-III. These findings were reinforced by skin infection studies with mice. Our data substantiate the prevailing model that MroQ is a mediator of cyclic peptide maturation.
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10
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Rao Y, Peng H, Shang W, Hu Z, Yang Y, Tan L, Li M, Zhou R, Rao X. A vancomycin resistance-associated WalK(S221P) mutation attenuates the virulence of vancomycin-intermediate Staphylococcus aureus. J Adv Res 2022; 40:167-178. [PMID: 36100324 PMCID: PMC9481939 DOI: 10.1016/j.jare.2021.11.015] [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: 11/02/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 11/25/2022] Open
Abstract
INTRODUCTION Vancomycin-intermediate Staphylococcus aureus (VISA) is typically associated with a decline in virulence. We previously reported a WalK(S221P) mutation that plays an important role in mediating vancomycin resistance in VISA XN108. Whether this mutation is implicated in bacterial virulence remains unknown. OBJECTIVES This study aimed to investigate the effect of WalK(S221P) mutation on the virulence of VISA and the underlying mechanism of this effect. METHODS The influence of WalK(S221P) mutation on VISA virulence and its underlying mechanism were explored using animal models, RNA-seq analysis, RT-qPCR, hemolytic assay, slide coagulase test, Western blot, β-galactosidase assay, and electrophoresis mobility shift assay (EMSA). RESULTS Compared with XN108, WalK(S221P)-reverted strain XN108-R exacerbated cutaneous infections with increased lesion size and extensive inflammatory infiltration in mouse models. The bacterial loads of S. aureus XN108-R in murine kidney increased compared with those of XN108. RNA-seq analysis showed upregulation of a set of virulence genes in XN108-R, which exhibited greater hemolytic and stronger coagulase activities compared with XN108. Introduction of WalK(S221P) to methicillin-resistant S. aureus USA300 and methicillin-susceptible strain Newman increased the vancomycin resistance of the mutants, which exhibited reduced hemolytic activities and decreased expression levels of many virulence factors compared with their progenitors. WalK(S221P) mutation weakened agr promoter-controlled β-galactosidase activity. EMSA results showed that WalK-phosphorylated WalR could directly bind to the agr promoter region, whereas WalK(S221P)-activated WalR reduced binding to the target promoter. Inactivation of agr in S. aureus did not affect their vancomycin susceptibility but mitigated the virulence alterations caused by WalK(S221P) mutation. CONCLUSION The results of our study indicate that WalK(S221P) mutation can enhance vancomycin resistance in S. aureus of diverse genetic backgrounds. WalK(S221P)- bearing S. aureus strains exhibit reduced virulence. WalK(S221P) mutation may directly impair the activation of the agr system by WalR, thereby decreasing the expression of virulence factors in VISA.
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Affiliation(s)
- Yifan Rao
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Chongqing 400038, China; Department of Emergency Medicine, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing 400037, China
| | - Huagang Peng
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Weilong Shang
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Zhen Hu
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Yi Yang
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Li Tan
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Chongqing 400038, China
| | - Ming Li
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Chongqing 400038, China.
| | - Renjie Zhou
- Department of Emergency Medicine, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing 400037, China.
| | - Xiancai Rao
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Chongqing 400038, China.
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11
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Ogura K, Furuya H, Takahashi N, Shibata K, Endo M, Watanabe S, Cui L, Miyoshi-Akiyama T, Okamoto S, Ogai K, Sugama J. Interspecies Regulation Between Staphylococcus caprae and Staphylococcus aureus Colonized on Healed Skin After Injury. Front Microbiol 2022; 13:818398. [PMID: 35300478 PMCID: PMC8921658 DOI: 10.3389/fmicb.2022.818398] [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: 11/19/2021] [Accepted: 01/20/2022] [Indexed: 12/04/2022] Open
Abstract
Staphylococcus spp. colonize commensally on the human skin. Some commensal coagulase-negative staphylococci and Staphylococcus aureus are also involved in nosocomial infections. Bacteria were collected from skin healed from pressure injury (PI). After the collection time points, some patients suffered from recurrent PI (RPI). This study analyzed the characteristics of Staphylococcus spp. on healed skin before recurrence between healed skin that suffered from RPI within 6 weeks (RPI group) and healed skin that did not suffer within the duration (non-RPI group) by Staphylococcus spp.-specific sequencing. Of the seven patients in the RPI group, two were dominated by S. aureus and four by Staphylococcus caprae, coagulase-negative human commensal staphylococci in the RPI group. Using mouse models, both S. caprae and S. aureus, but not Staphylococcus epidermidis, colonized on skin healed from injury at significantly higher rates than normal skin. Although subcutaneous injection of S. caprae did not induce lesion formation, the bacterium exhibited high hemolytic activity on human red blood cells. Lesion formation by subcutaneous injection of S. aureus was significantly suppressed in the presence of S. caprae. The hemolytic activity of rabbit blood cells of S. aureus was suppressed by S. caprae, whereas the hemolytic activity of S. caprae was dramatically suppressed by S. aureus. Data indicated that each of the two Staphylococcus spp. suppresses the pathogenicity of the other and that the imbalance between the two is associated with RPI.
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Affiliation(s)
- Kohei Ogura
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Hiroka Furuya
- Department of Clinical Laboratory Science, Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Natsuki Takahashi
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Kana Shibata
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Maho Endo
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan
| | - Shinya Watanabe
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Longzhu Cui
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Tohru Miyoshi-Akiyama
- Pathogenic Microbe Laboratory, Research Institute, National Center for Global Health and Medicine, Shinjuku, Japan
| | - Shigefumi Okamoto
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan.,Department of Clinical Laboratory Science, Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Kazuhiro Ogai
- AI Hospital/Macro Signal Dynamics Research and Development Center, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Junko Sugama
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa, Japan.,Research Center for Implementation Nursing Science Initiative, School of Health Sciences, Fujita Health University, Toyoake, Japan
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12
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Montagut EJ, Acosta G, Albericio F, Royo M, Godoy-Tena G, Lacoma A, Prat C, Salvador JP, Marco MP. Direct Quantitative Immunochemical Analysis of Autoinducer Peptide IV for Diagnosing and Stratifying Staphylococcus aureus Infections. ACS Infect Dis 2022; 8:645-656. [PMID: 35175740 PMCID: PMC8922274 DOI: 10.1021/acsinfecdis.1c00670] [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] [Indexed: 11/29/2022]
Abstract
An immunochemical strategy to detect and quantify AIP-IV, the quorum sensing (QS) signaling molecule produced by Staphylococcus aureus agr type IV, is reported here for the first time. Theoretical calculations and molecular modeling studies have assisted on the design and synthesis of a suitable peptide hapten (AIPIVS), allowing to obtain high avidity and specific antibodies toward this peptide despite its low molecular weight. The ELISA developed achieves an IC50 value of 2.80 ± 0.17 and an LOD of 0.19 ± 0.06 nM in complex media such as 1/2 Tryptic Soy Broth. Recognition of other S. aureus AIPs (I-III) is negligible (cross-reactivity below 0.001%), regardless of the structural similarities. A pilot study with a set of clinical isolates from patients with airways infection or colonization demonstrates the potential of this ELISA to perform biomedical investigations related to the role of QS in pathogenesis and the association between dysfunctional agr or the agr type with unfavorable clinical outcomes. The AIP-IV levels could be quantified in the low nanomolar range in less than 1 h after inoculating agr IV-genotyped isolates in the culture broth, while those genotyped as I-III did not show any immunoreactivity after a 48 h growth, pointing to the possibility to use this technology for phenotyping S. aureus. The research strategy here reported can be extended to the rest of the AIP types of S. aureus, allowing the development of powerful multiplexed chips or point-of-care (PoC) diagnostic devices to unequivocally identify its presence and its agr type on samples from infected patients.
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Affiliation(s)
- Enrique-J. Montagut
- Nanobiotechnology for Diagnostics (Nb4D), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
| | - Gerardo Acosta
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
- Multivalent Systems for Nanomedicine (MS4N), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
| | - Fernando Albericio
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
- Multivalent Systems for Nanomedicine (MS4N), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
- Department of Organic Chemistry, Faculty of Chemistry, University of Barcelona, 08028 Barcelona, Spain
- School of Chemistry and Physics, University of KwaZulu-Natal, 4000 Durban, South Africa
| | - Miriam Royo
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
- Multivalent Systems for Nanomedicine (MS4N), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
| | - Gerard Godoy-Tena
- Servei de Microbiologia, Hospital Universitari Germans Trias i Pujol, Institut d’Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Alicia Lacoma
- Servei de Microbiologia, Hospital Universitari Germans Trias i Pujol, Institut d’Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Cristina Prat
- Servei de Microbiologia, Hospital Universitari Germans Trias i Pujol, Institut d’Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, 3584 Utrecht, the Netherlands
| | - Juan-Pablo Salvador
- Nanobiotechnology for Diagnostics (Nb4D), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
| | - María-Pilar Marco
- Nanobiotechnology for Diagnostics (Nb4D), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
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13
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Morizane A, Uehara Y, Kitamura S, Komori M, Matsushita M, Takeuchi S, Seo H. Staphylococcus aureus
nasal colonization increases the risk of cedar pollinosis. J Gen Fam Med 2022; 23:172-176. [PMID: 35509329 PMCID: PMC9062552 DOI: 10.1002/jgf2.530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 02/02/2022] [Accepted: 02/09/2022] [Indexed: 11/09/2022] Open
Abstract
Background One‐third of the people in Japan are colonized with Staphylococcus aureus (S. aureus) and suffer from virulence factor‐mediated subclinical inflammation of the nares. We investigated whether subclinical inflammation contributed to cedar pollinosis affecting 20 million people annually. Methods The study participants were 814 inhabitants of the A or B prefectures. We compared the colonization rate and population structure of S. aureus, in association with the prevalence of cedar pollinosis, between participants in these two areas. Results A prefecture had twice the annual amount of airborne cedar pollen compared with B. The prevalence of cedar pollinosis was significantly higher in A (23.5%) than in B (13.1%) (p = 0.0004). Moreover, the prevalence of cedar pollinosis was higher in female participants (23.3%) than in male participants (14.7%) (p = 0.003). In addition, the prevalence of cedar pollinosis was higher in S. aureus carriers (24.2%) than in S. aureus noncarriers (17.9%) (p = 0.03). The isolation rate of clonal complex (CC) 508 was higher in the A group (21%) than in the B group (7%) (p = 0.015). Conclusion Nasal colonization of S. aureus is a major risk factor for cedar pollinosis. However, the direct mechanism of this risk is currently unknown. The prevalence of cedar pollinosis in the research area was proportional to the amount of cedar pollen. The prevalence of cedar pollinosis was higher in S. aureus carriers (24.2%) than in S. aureus noncarriers (17.9%) (p = 0.03). The prevalence of cedar pollinosis was higher in female participants (23.3%) than in male participants (14.7%) (p = 0.003).
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Affiliation(s)
- Atsushi Morizane
- Department of General Medicine Kochi Medical School Hospital Nankoku Japan
| | - Yoshio Uehara
- Department of General Medicine Kochi Medical School Hospital Nankoku Japan
| | - Satoko Kitamura
- Department of General Medicine Kochi Medical School Hospital Nankoku Japan
| | - Masahiro Komori
- Department of Otolaryngology Kochi Medical School Nankoku Japan
| | | | - Seisho Takeuchi
- Department of General Medicine Kochi Medical School Hospital Nankoku Japan
| | - Hiromi Seo
- Department of General Medicine Kochi Medical School Hospital Nankoku Japan
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14
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Tan L, Huang Y, Shang W, Yang Y, Peng H, Hu Z, Wang Y, Rao Y, Hu Q, Rao X, Hu X, Li M, Chen K, Li S. Accessory Gene Regulator (agr) Allelic Variants in Cognate Staphylococcus aureus Strain Display Similar Phenotypes. Front Microbiol 2022; 13:700894. [PMID: 35295312 PMCID: PMC8919982 DOI: 10.3389/fmicb.2022.700894] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 01/14/2022] [Indexed: 11/13/2022] Open
Abstract
The accessory gene regulator (agr) quorum-sensing system is an important global regulatory system of Staphylococcus aureus and contributes to its pathogenicity. The S. aureus agr system is divided into four agr groups based on the amino acid polymorphisms of AgrB, AgrD, and AgrC. The agr activation is group-specific, resulting in variations in agr activity and pathogenicity among the four agr groups. Strains with divergent agr system always have different phenotypes. In the present report, we, respectively, exchanged the agr system of a certain S. aureus with other three agr alleles and assessed the corresponding phenotypes of these congenic strains. Replacement of the agr system led to significant variations in hemolytic activity, protein expression, and virulence gene expression comparing with that of the parental strain. Interestingly, we found that the biological characteristics of these agr congenic strains in the same strain background were highly similar to each other, and the allele-dependent differences of the agr systems were weakened. These findings indicate that the allele-dependent agr predilections of S. aureus are determined by some factors in addition to the polymorphisms of AgrB, AgrD, and AgrC. Future studies may reveal the novel mechanism to improve our understanding of the agr network.
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Affiliation(s)
- Li Tan
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yuyang Huang
- Queen Mary College, Nanchang University, Nanchang, China
| | - Weilong Shang
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yi Yang
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Huagang Peng
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Zhen Hu
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yuting Wang
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Yifan Rao
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Qiwen Hu
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Xiancai Rao
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Xiaomei Hu
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Ming Li
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
| | - Kaisen Chen
- The First Affiliated Hospital of Nanchang University, Nanchang, China
- *Correspondence: Kaisen Chen,
| | - Shu Li
- College of Basic Medical Sciences, Army Medical University, Chongqing, China
- Shu Li,
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15
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Hugouvieux-Cotte-Pattat N, Royer M, Gueguen E, Le Guen P, Süssmuth RD, Reverchon S, Cociancich S. Specificity and genetic polymorphism in the Vfm quorum sensing system of plant pathogenic bacteria of the genus Dickeya. Environ Microbiol 2022; 24:1467-1483. [PMID: 35014170 PMCID: PMC9306890 DOI: 10.1111/1462-2920.15889] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 12/26/2021] [Indexed: 12/11/2022]
Abstract
The Vfm quorum sensing (QS) system is preponderant for the virulence of different species of the bacterial genus Dickeya. The vfm gene cluster encodes 26 genes involved in the production, sensing or transduction of the QS signal. To date, the Vfm QS signal has escaped detection by analytical chemistry methods. However, we report here a strain‐specific polymorphism in the biosynthesis genes vfmO and vfmP, which is predicted to be related to the production of different analogues of the QS signal. Consequently, the Vfm communication could be impossible between strains possessing different variants of the genes vfmO/P. We constructed three Vfm QS biosensor strains possessing different vfmO/P variants and compared these biosensors for their responses to samples prepared from 34 Dickeya strains possessing different vfmO/P variants. A pattern of specificity was demonstrated, providing evidence that the polymorphism in the genes vfmO/P determines the biosynthesis of different analogues of the QS signal. Unexpectedly, this vfmO/P‐dependent pattern of specificity is linked to a polymorphism in the ABC transporter gene vfmG, suggesting an adaptation of the putative permease VfmG to specifically bind different analogues of the QS signal. Accordingly, we discuss the possible involvement of VfmG as co‐sensor of the Vfm two‐component regulatory system.
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Affiliation(s)
| | - Monique Royer
- CIRAD, UMR PHIM, Montpellier, F-34398, France.,PHIM, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Erwan Gueguen
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, Villeurbanne, F-69622, France
| | - Paul Le Guen
- CIRAD, UMR PHIM, Montpellier, F-34398, France.,PHIM, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Roderich D Süssmuth
- Institut für Chemie, Technische Universität Berlin, Berlin, D-10623, Germany
| | - Sylvie Reverchon
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, Villeurbanne, F-69622, France
| | - Stéphane Cociancich
- CIRAD, UMR PHIM, Montpellier, F-34398, France.,PHIM, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
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16
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Trans-Cinnamaldehyde Attenuates Enterococcus faecalis Virulence and Inhibits Biofilm Formation. Antibiotics (Basel) 2021; 10:antibiotics10060702. [PMID: 34208134 PMCID: PMC8230787 DOI: 10.3390/antibiotics10060702] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/09/2021] [Accepted: 06/09/2021] [Indexed: 11/21/2022] Open
Abstract
Enterococcus faecalis as an important nosocomial pathogen is critically implicated in the pathogenesis of endocarditis, urinary tract, and persistent root canal infections. Its major virulence attributes (biofilm formation, production of proteases, and hemolytic toxins) enable it to cause extensive host tissue damage. With the alarming increase in enterococcal resistance to antibiotics, novel therapeutics are required to inhibit E. faecalis biofilm formation and virulence. Trans-cinnamaldehyde (TC), the main phytochemical in cinnamon essential oils, has demonstrated promising activity against a wide range of pathogens. Here, we comprehensively investigated the effect of TC on planktonic growth, biofilm formation, proteolytic and hemolytic activities, as well as gene regulation in E. faecalis. Our findings revealed that sub-inhibitory concentrations of TC reduced biofilm formation, biofilm exopolysaccharides, as well as its proteolytic and hemolytic activities. Mechanistic studies revealed significant downregulation of the quorum sensing fsr locus and downstream gelE, which are major virulence regulators in E. faecalis. Taken together, our study highlights the potential of TC to inhibit E. faecalis biofilm formation and its virulence.
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17
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Optimal Response to Quorum-Sensing Signals Varies in Different Host Environments with Different Pathogen Group Size. mBio 2020; 11:mBio.00535-20. [PMID: 32487754 PMCID: PMC7267880 DOI: 10.1128/mbio.00535-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Quorum sensing describes the ability of microbes to alter gene regulation according to their local population size. Some successful theory suggests that this is a form of cooperation, namely, investment in shared products is only worthwhile if there are sufficient bacteria making the same product. This theory can explain the genetic diversity in these signaling systems in Gram-positive bacteria, such as Bacillus and Staphylococcus sp. The possible advantages gained by rare genotypes (which can exploit the products of their more common neighbors) could explain why different genotypes can coexist. We show that while these social interactions can occur in simple laboratory experiments, they do not occur in naturalistic infections using an invertebrate pathogen, Bacillus thuringiensis. Instead, our results suggest that different genotypes are adapted to differently sized hosts. Overall, social models are not easily applied to this system, implying that a different explanation for this form of quorum sensing is required. The persistence of genetic variation in master regulators of gene expression, such as quorum-sensing systems, is hard to explain. Here, we investigated two alternative hypotheses for the prevalence of polymorphic quorum sensing in Gram-positive bacteria, i.e., the use of different signal/receptor pairs (‘pherotypes’) to regulate the same functions. First, social interactions between pherotypes or ‘facultative cheating’ may favor rare variants that exploit the signals of others. Second, different pherotypes may increase fitness in different environments. We evaluated these hypotheses in the invertebrate pathogen Bacillus thuringiensis, using three pherotypes expressed in a common genetic background. Facultative cheating could occur in well-mixed host homogenates provided there was minimal cross talk between competing pherotypes. However, facultative cheating did not occur when spatial structure was increased in static cultures or in naturalistic oral infections, where common pherotypes had higher fitness. There was clear support for environment-dependent fitness; pherotypes varied in responsiveness to signals and in mean competitive fitness. Notably, competitive fitness varied with group size. In contrast to typical social evolution models of quorum sensing which predict higher response to signal at larger group size, the pherotype with highest responsiveness to signals performed best in smaller hosts where infections have a lower pathogen group size. In this system, low signal abundance appears to limit fitness in hosts, while the optimal level of response to signals varies in different host environments.
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18
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Modulation of Quorum Sensing as an Adaptation to Nodule Cell Infection during Experimental Evolution of Legume Symbionts. mBio 2020; 11:mBio.03129-19. [PMID: 31992622 PMCID: PMC6989110 DOI: 10.1128/mbio.03129-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Over millions of years, changes have occurred in regulatory circuitries in response to genome reorganization and/or persistent changes in environmental conditions. How bacteria optimize regulatory circuitries is crucial to understand bacterial adaptation. Here, we analyzed the experimental evolution of the plant pathogen Ralstonia solanacearum into legume symbionts after the transfer of a natural plasmid encoding the essential mutualistic genes. We showed that the Phc quorum sensing system required for the virulence of the ancestral bacterium was reconfigured to improve intracellular infection of root nodules induced by evolved Ralstonia A single mutation in either the PhcB autoinducer synthase or the PhcQ regulator of the sensory cascade tuned the kinetics of activation of the central regulator PhcA in response to cell density so that the minimal stimulatory concentration of autoinducers needed for a given response was increased. Yet, a change in the expression of a PhcA target gene was observed in infection threads progressing in root hairs, suggesting early programming for the late accommodation of bacteria in nodule cells. Moreover, this delayed switch to the quorum sensing mode decreased the pathogenicity of the ancestral strain, illustrating the functional plasticity of regulatory systems and showing how a small modulation in signal response can produce drastic changes in bacterial lifestyle.IMPORTANCE Rhizobia are soil bacteria from unrelated genera able to form a mutualistic relationship with legumes. Bacteria induce the formation of root nodules, invade nodule cells, and fix nitrogen to the benefit of the plant. Rhizobial lineages emerged from the horizontal transfer of essential symbiotic genes followed by genome remodeling to activate and/or optimize the acquired symbiotic potential. This evolutionary scenario was replayed in a laboratory evolution experiment in which the plant pathogen Ralstonia solanacearum successively evolved the capacities to nodulate Mimosa pudica and poorly invade, then massively invade, nodule cells. In some lines, the improvement of intracellular infection was achieved by mutations modulating a quorum sensing regulatory system of the ancestral strain. This modulation that affects the activity of a central regulator during the earliest stages of symbiosis has a huge impact on late stages of symbiosis. This work showed that regulatory rewiring is the main driver of this pathogeny-symbiosis transition.
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19
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Azmi K, Qrei W, Abdeen Z. Screening of genes encoding adhesion factors and biofilm production in methicillin resistant strains of Staphylococcus aureus isolated from Palestinian patients. BMC Genomics 2019; 20:578. [PMID: 31299899 PMCID: PMC6624993 DOI: 10.1186/s12864-019-5929-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 06/24/2019] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Intercellular adhesion and biofilm production by Staphylococcus aureus makes these bacteria resistant to antimicrobial therapy. Here, Methicillin-resistant Staphylococcus aureus (MRSA) strains were characterized and the prevalence of genes encoding adhesion factors and biofilm formation was determined. RESULTS All 248 MRSA isolates identified by cefoxitin disc diffusion were positive for the mecA gene. SCCmec-IV was the most frequently detected genotype (92.7%) and SCCmec-IVa was also very prevalent (84.3%). The quantitative microtiter plate assay showed that all the isolates were able to produce biofilm with levels ranging from high (21%) to moderate (46.4%) to low (32.7%). All the strains possessed the icaD/icaA genes and produced biofilm (P < 0.05). None of the isolates possessed the bap gene. Furthermore, 94.8% of the isolates were positive for eno, 80.2% for clfA and for clfB, 78.2% for fnbA, 76.2% for ebps, 62.2% for fib, 39.9% for cna and 29.0% for fnbB. Also, nearly 69.8% of the isolates were positive for the gene sarA. All four agr groups were present: agr group 1 was predominant with 39.5%; agr group 3. agr group 2 and 3 strains carried more toxin-producing genes, and frequently produced more toxin. Sixty-six (26.6%) of the strains were multidrug resistant. All were vancomycin sensitive. Agr group I is more resistant to ciprofloxacin and gentamicin while agr group III is more resistant to erythromycin. Maximum sensitivity was to gentamicin and SXT, and they could be considered drugs of choice for controlling MRSA mediated infections in this region. CONCLUSIONS Biofilm development in MRSA might be an ica dependent and one needs to investigate the involvement of other global regulators, agr and sarA, and their contribution to the biofilm phenotype, as the high rate of biofilm production among the studied strains of S. aureus.
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Affiliation(s)
- Kifaya Azmi
- Biochemistry and Molecular Biology Department, Al-Quds Nutrition and Health Research Institute, Faculty of Medicine, Al-Quds University, Abu Deis, The West Bank, Palestine. .,Al-Quds Public Health Society, Jerusalem, Palestine. .,Faculty of Medicine, Al-Quds Nutrition and Health Research Institute, Al-Quds University, Abu-Deis, P.O. Box 20760, The West Bank, Palestine.
| | - Walaa Qrei
- Al-Quds Public Health Society, Jerusalem, Palestine
| | - Ziad Abdeen
- Al-Quds Public Health Society, Jerusalem, Palestine.,Faculty of Medicine, Al-Quds Nutrition and Health Research Institute, Al-Quds University, Abu-Deis, P.O. Box 20760, The West Bank, Palestine
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20
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Silva KPT, Boedicker JQ. A neural network model predicts community-level signaling states in a diverse microbial community. PLoS Comput Biol 2019; 15:e1007166. [PMID: 31233492 PMCID: PMC6611639 DOI: 10.1371/journal.pcbi.1007166] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 07/05/2019] [Accepted: 06/06/2019] [Indexed: 11/19/2022] Open
Abstract
Signal crosstalk within biological communication networks is common, and such crosstalk can have unexpected consequences for decision making in heterogeneous communities of cells. Here we examined crosstalk within a bacterial community composed of five strains of Bacillus subtilis, with each strain producing a variant of the quorum sensing peptide ComX. In isolation, each strain produced one variant of the ComX signal to induce expression of genes associated with bacterial competence. When strains were combined, a mixture of ComX variants was produced resulting in variable levels of gene expression. To examine gene regulation in mixed communities, we implemented a neural network model. Experimental quantification of asymmetric crosstalk between pairs of strains parametrized the model, enabling the accurate prediction of activity within the full five-strain network. Unlike the single strain system in which quorum sensing activated upon exceeding a threshold concentration of the signal, crosstalk within the five-strain community resulted in multiple community-level quorum sensing states, each with a unique combination of quorum sensing activation among the five strains. Quorum sensing activity of the strains within the community was influenced by the combination and ratio of strains as well as community dynamics. The community-level signaling state was altered through an external signal perturbation, and the output state depended on the timing of the perturbation. Given the ubiquity of signal crosstalk in diverse microbial communities, the application of such neural network models will increase accuracy of predicting activity within microbial consortia and enable new strategies for control and design of bacterial signaling networks.
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Affiliation(s)
- Kalinga Pavan T. Silva
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, United States of America
| | - James Q. Boedicker
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, United States of America
- Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
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21
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Cosgriff CJ, White CR, Teoh WP, Grayczyk JP, Alonzo F. Control of Staphylococcus aureus Quorum Sensing by a Membrane-Embedded Peptidase. Infect Immun 2019; 87:e00019-19. [PMID: 30833334 PMCID: PMC6479040 DOI: 10.1128/iai.00019-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 02/23/2019] [Indexed: 02/08/2023] Open
Abstract
Gram-positive bacteria process and release small peptides, or pheromones, that act as signals for the induction of adaptive traits, including those involved in pathogenesis. One class of small signaling pheromones is the cyclic autoinducing peptides (AIPs), which regulate expression of genes that orchestrate virulence and persistence in a range of microbes, including staphylococci, listeriae, clostridia, and enterococci. In a genetic screen for Staphylococcus aureus secreted virulence factors, we identified an S. aureus mutant containing an insertion in the gene SAUSA300_1984 (mroQ), which encodes a putative membrane-embedded metalloprotease. A ΔmroQ mutant exhibited impaired induction of Toll-like receptor 2-dependent inflammatory responses from macrophages but elicited greater production of the inflammatory cytokine interleukin-1β and was attenuated in a murine skin and soft tissue infection model. The ΔmroQ mutant phenocopies an S. aureus mutant containing a deletion of the accessory gene regulatory system (Agr), wherein both strains have significantly reduced production of secreted toxins and virulence factors but increased surface protein A abundance. The Agr system controls virulence factor gene expression in S. aureus by sensing the accumulation of AIP via the histidine kinase AgrC and the response regulator AgrA. We provide evidence to suggest that MroQ acts within the Agr pathway to facilitate the optimal processing or export of AIP for signal amplification through AgrC/A and induction of virulence factor gene expression. Mutation of MroQ active-site residues significantly reduces AIP signaling and attenuates virulence. Altogether, this work identifies a new component of the Agr quorum-sensing circuit that is critical for the production of S. aureus virulence factors.
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Affiliation(s)
- Chance J Cosgriff
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
| | - Chelsea R White
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
| | - Wei Ping Teoh
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
| | - James P Grayczyk
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
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Lakemeyer M, Zhao W, Mandl FA, Hammann P, Sieber SA. Thinking Outside the Box-Novel Antibacterials To Tackle the Resistance Crisis. Angew Chem Int Ed Engl 2018; 57:14440-14475. [PMID: 29939462 DOI: 10.1002/anie.201804971] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Indexed: 12/13/2022]
Abstract
The public view on antibiotics as reliable medicines changed when reports about "resistant superbugs" appeared in the news. While reasons for this resistance development are easily spotted, solutions for re-establishing effective antibiotics are still in their infancy. This Review encompasses several aspects of the antibiotic development pipeline from very early strategies to mature drugs. An interdisciplinary overview is given of methods suitable for mining novel antibiotics and strategies discussed to unravel their modes of action. Select examples of antibiotics recently identified by using these platforms not only illustrate the efficiency of these measures, but also highlight promising clinical candidates with therapeutic potential. Furthermore, the concept of molecules that disarm pathogens by addressing gatekeepers of virulence will be covered. The Review concludes with an evaluation of antibacterials currently in clinical development. Overall, this Review aims to connect select innovative antimicrobial approaches to stimulate interdisciplinary partnerships between chemists from academia and industry.
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Affiliation(s)
- Markus Lakemeyer
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Weining Zhao
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Franziska A Mandl
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Peter Hammann
- R&D Therapeutic Area Infectious Diseases, Sanofi-Aventis (Deutschland) GmbH, Industriepark Höchst, 65926, Frankfurt am Main, Germany
| | - Stephan A Sieber
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
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23
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Lakemeyer M, Zhao W, Mandl FA, Hammann P, Sieber SA. Über bisherige Denkweisen hinaus - neue Wirkstoffe zur Überwindung der Antibiotika-Krise. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201804971] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Markus Lakemeyer
- Fakultät für Chemie; Lehrstuhl für Organische Chemie II, Center for Integrated Protein Science (CIPSM); Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Weining Zhao
- Fakultät für Chemie; Lehrstuhl für Organische Chemie II, Center for Integrated Protein Science (CIPSM); Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Franziska A. Mandl
- Fakultät für Chemie; Lehrstuhl für Organische Chemie II, Center for Integrated Protein Science (CIPSM); Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Peter Hammann
- R&D Therapeutic Area Infectious Diseases; Sanofi-Aventis (Deutschland) GmbH; Industriepark Höchst 65926 Frankfurt am Main Deutschland
| | - Stephan A. Sieber
- Fakultät für Chemie; Lehrstuhl für Organische Chemie II, Center for Integrated Protein Science (CIPSM); Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
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Genome Plasticity of agr-Defective Staphylococcus aureus during Clinical Infection. Infect Immun 2018; 86:IAI.00331-18. [PMID: 30061376 PMCID: PMC6204747 DOI: 10.1128/iai.00331-18] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/21/2018] [Indexed: 01/05/2023] Open
Abstract
Therapy for bacteremia caused by Staphylococcus aureus is often ineffective, even when treatment conditions are optimal according to experimental protocols. Adapted subclones, such as those bearing mutations that attenuate agr-mediated virulence activation, are associated with persistent infection and patient mortality. Therapy for bacteremia caused by Staphylococcus aureus is often ineffective, even when treatment conditions are optimal according to experimental protocols. Adapted subclones, such as those bearing mutations that attenuate agr-mediated virulence activation, are associated with persistent infection and patient mortality. To identify additional alterations in agr-defective mutants, we sequenced and assembled the complete genomes of clone pairs from colonizing and infected sites of several patients in whom S. aureus demonstrated a within-host loss of agr function. We report that events associated with agr inactivation result in agr-defective blood and nares strain pairs that are enriched in mutations compared to pairs from wild-type controls. The random distribution of mutations between colonizing and infecting strains from the same patient, and between strains from different patients, suggests that much of the genetic complexity of agr-defective strains results from prolonged infection or therapy-induced stress. However, in one of the agr-defective infecting strains, multiple genetic changes resulted in increased virulence in a murine model of bloodstream infection, bypassing the mutation of agr and raising the possibility that some changes were selected. Expression profiling correlated the elevated virulence of this agr-defective mutant to restored expression of the agr-regulated ESAT6-like type VII secretion system, a known virulence factor. Thus, additional mutations outside the agr locus can contribute to diversification and adaptation during infection by S. aureus agr mutants associated with poor patient outcomes.
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25
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Svenningsen SL. Small RNA-Based Regulation of Bacterial Quorum Sensing and Biofilm Formation. Microbiol Spectr 2018; 6:10.1128/microbiolspec.rwr-0017-2018. [PMID: 30003870 PMCID: PMC11633610 DOI: 10.1128/microbiolspec.rwr-0017-2018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Indexed: 02/08/2023] Open
Abstract
Quorum sensing is a vital property of bacteria that enables community-wide coordination of collective behaviors. A key example of such a behavior is biofilm formation, in which groups of bacteria invest in synthesizing a protective, joint extracellular matrix. Quorum sensing involves the production, release, and subsequent detection of extracellular signaling molecules called autoinducers. The architecture of quorum-sensing signal transduction pathways is highly variable among different species of bacteria, but frequently involves posttranscriptional regulation carried out by small regulatory RNA molecules. This review illustrates the diverse roles small trans-acting regulatory RNAs can play, from constituting a network's core to auxiliary roles in adjusting the rate of autoinducer synthesis, mediating cross talk among different parts of a network, or integrating different regulatory inputs to trigger appropriate changes in gene expression. The emphasis is on describing how the study of small RNA-based regulation in quorum sensing and biofilm formation has uncovered new general properties or expanded our understanding of bacterial riboregulation.
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Tuning of the Lethal Response to Multiple Stressors with a Single-Site Mutation during Clinical Infection by Staphylococcus aureus. mBio 2017; 8:mBio.01476-17. [PMID: 29066545 PMCID: PMC5654930 DOI: 10.1128/mbio.01476-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The agr system of Staphylococcus aureus promotes invasion of host tissues, and as expected, agents that block agr quorum sensing have anti-infective properties. Paradoxically, agr-defective mutants are frequently recovered from patients, especially those persistently infected with S. aureus We found that an agr deficiency increased survival of cultured bacteria during severe stress, such as treatment with gentamicin, ciprofloxacin, heat, or low pH. With daptomycin, deletion of agr decreased survival. Therefore, agr activity can be either detrimental or protective, depending on the type of lethal stress. Deletion of agr had no effect on the ability of the antimicrobials to block bacterial growth, indicating that agr effects are limited to lethal action. Thus, the effect of an agr deletion is on bacterial tolerance, not resistance. For gentamicin and daptomycin, activity can be altered by agr-regulated secreted factors. For ciprofloxacin, a detrimental function was downregulation of glutathione peroxidase (bsaA), an enzyme responsible for defense against oxidative stress. Deficiencies in agr and bsaA were epistatic for survival, consistent with agr having a destructive role mediated by reactive oxygen species. Enhanced susceptibility to lethal stress by wild-type agr, particularly antimicrobial stress, helps explain why inactivating mutations in S. aureus agr commonly occur in hospitalized patients during infection. Moreover, the agr quorum-sensing system of S. aureus provides a clinically relevant example in which a single-step change in the response to severe stress alters the evolutionary path of a pathogen during infection.IMPORTANCE When phenotypes produced in response to an environmental stress are inadequate to buffer against that stress, changes that do buffer may become genetically encoded by natural selection. A clinically relevant example is seen with S. aureus mutants that are deficient in the key virulence regulator agr Paradoxically, defects in agr are selected during serious hospital infection and have been associated with worse outcome. The current work helps resolve this paradox: agr mutants are often less readily killed by lethal stressors without affecting MIC, a phenomenon known as tolerance. Our results indicate that tolerance, which would not be detected as resistance, can be selected in clinical settings. The data also support the ideas that (i) S. aureus broadly hedges against environmental change and stress through genome plasticity, (ii) reactive oxygen can be involved in the self-destructive response in bacteria, and (iii) therapeutic targeting of agr and virulence can be counterproductive.
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Yusufaly TI, Boedicker JQ. Mapping quorum sensing onto neural networks to understand collective decision making in heterogeneous microbial communities. Phys Biol 2017; 14:046002. [PMID: 28656904 DOI: 10.1088/1478-3975/aa7c1e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Microbial communities frequently communicate via quorum sensing (QS), where cells produce, secrete, and respond to a threshold level of an autoinducer (AI) molecule, thereby modulating gene expression. However, the biology of QS remains incompletely understood in heterogeneous communities, where variant bacterial strains possess distinct QS systems that produce chemically unique AIs. AI molecules bind to 'cognate' receptors, but also to 'non-cognate' receptors found in other strains, resulting in inter-strain crosstalk. Understanding these interactions is a prerequisite for deciphering the consequences of crosstalk in real ecosystems, where multiple AIs are regularly present in the same environment. As a step towards this goal, we map crosstalk in a heterogeneous community of variant QS strains onto an artificial neural network model. This formulation allows us to systematically analyze how crosstalk regulates the community's capacity for flexible decision making, as quantified by the Boltzmann entropy of all QS gene expression states of the system. In a mean-field limit of complete cross-inhibition between variant strains, the model is exactly solvable, allowing for an analytical formula for the number of variants that maximize capacity as a function of signal kinetics and activation parameters. An analysis of previous experimental results on the Staphylococcus aureus two-component Agr system indicates that the observed combination of variant numbers, gene expression rates and threshold concentrations lies near this critical regime of parameter space where capacity peaks. The results are suggestive of a potential evolutionary driving force for diversification in certain QS systems.
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Affiliation(s)
- Tahir I Yusufaly
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States of America
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28
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Wang B, Zhao A, Xie Q, Olinares PD, Chait BT, Novick RP, Muir TW. Functional Plasticity of the AgrC Receptor Histidine Kinase Required for Staphylococcal Virulence. Cell Chem Biol 2017; 24:76-86. [PMID: 28065658 DOI: 10.1016/j.chembiol.2016.12.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 10/21/2016] [Accepted: 12/13/2016] [Indexed: 12/11/2022]
Abstract
Staphylococcus aureus employs the receptor histidine kinase (RHK), AgrC, to detect quorum-sensing (QS) pheromones, the autoinducer peptides (AIPs), which regulate the virulence of the bacterium. Variation in the QS circuit divides S. aureus into four subgroups, each producing a specific AIP-AgrC pair. While the timing of QS induction is known to differ among these subgroups, the molecular basis of this phenomenon is unknown. Here, we report the successful reconstitution of several AgrC variants and show that the agonist-induced activity of the receptors varies in a manner that accounts for these temporal differences in QS induction. Our studies also reveal a key regulatory hotspot on AgrC that controls the basal activity of RHK as well as the responsiveness of the system to ligand inputs. Collectively, these studies offer insights into the capacity of the RHK for adaptive evolution.
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Affiliation(s)
- Boyuan Wang
- Department of Chemistry, Frick Chemistry Laboratory, Princeton University, Washington Road, Princeton, NJ 08544-0015, USA; Graduate Program, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Aishan Zhao
- Department of Chemistry, Frick Chemistry Laboratory, Princeton University, Washington Road, Princeton, NJ 08544-0015, USA
| | - Qian Xie
- Department of Chemistry, Frick Chemistry Laboratory, Princeton University, Washington Road, Princeton, NJ 08544-0015, USA
| | - Paul Dominic Olinares
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Richard P Novick
- Department of Microbiology, Skirball Institute, NYU Medical Center, 540-562 First Avenue, New York, NY 10016, USA
| | - Tom W Muir
- Department of Chemistry, Frick Chemistry Laboratory, Princeton University, Washington Road, Princeton, NJ 08544-0015, USA.
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29
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Roetzer A, Jilma B, Eibl MM. Vaccine against toxic shock syndrome in a first-in-man clinical trial. Expert Rev Vaccines 2016; 16:81-83. [PMID: 27918218 DOI: 10.1080/14760584.2017.1268921] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
| | - Bernd Jilma
- b Department of Clinical Pharmacology , Medical University of Vienna , Vienna , Austria
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30
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Wang B, Muir TW. Regulation of Virulence in Staphylococcus aureus: Molecular Mechanisms and Remaining Puzzles. Cell Chem Biol 2016; 23:214-224. [PMID: 26971873 DOI: 10.1016/j.chembiol.2016.01.004] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 01/13/2016] [Accepted: 01/25/2016] [Indexed: 12/23/2022]
Abstract
The agr locus encodes a quorum-sensing (QS) circuit required for the virulence of a spectrum of Gram-positive pathogens and is, therefore, regarded as an important target for the development of chemotherapeutics. In recent years, many of the biochemical events in the Staphylococcus aureus agr circuit have been reconstituted and subject to quantitative analysis in vitro. This work, in conjunction with structural studies on several key players in the signaling circuit, has furnished mechanistic insights into the regulation and evolution of the agr QS system. Here, we review this progress and discuss the remaining open questions in the area. We also highlight advances in the discovery of small-molecule agr modulators and how the newly available biochemical and structural information might be leveraged for the design of next-generation therapeutics targeting the agr system.
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Affiliation(s)
- Boyuan Wang
- Frick Chemistry Laboratory, Department of Chemistry, Princeton University, Washington Road, Princeton, NJ 08544, USA; Graduate Program, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Tom W Muir
- Frick Chemistry Laboratory, Department of Chemistry, Princeton University, Washington Road, Princeton, NJ 08544, USA.
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31
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Canovas J, Baldry M, Bojer MS, Andersen PS, Grzeskowiak PK, Stegger M, Damborg P, Olsen CA, Ingmer H. Cross-Talk between Staphylococcus aureus and Other Staphylococcal Species via the agr Quorum Sensing System. Front Microbiol 2016; 7:1733. [PMID: 27877157 PMCID: PMC5099252 DOI: 10.3389/fmicb.2016.01733] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/17/2016] [Indexed: 11/13/2022] Open
Abstract
Staphylococci are associated with both humans and animals. While most are non-pathogenic colonizers, Staphylococcus aureus is an opportunistic pathogen capable of causing severe infections. S. aureus virulence is controlled by the agr quorum sensing system responding to secreted auto-inducing peptides (AIPs) sensed by AgrC, a two component histidine kinase. agr loci are found also in other staphylococcal species and for Staphylococcus epidermidis, the encoded AIP represses expression of agr regulated virulence genes in S. aureus. In this study we aimed to better understand the interaction between staphylococci and S. aureus, and show that this interaction may eventually lead to the identification of new anti-virulence candidates to target S. aureus infections. Here we show that culture supernatants of 37 out of 52 staphylococcal isolates representing 17 different species inhibit S. aureus agr. The dog pathogen, Staphylococcus schleiferi, expressed the most potent inhibitory activity and was active against all four agr classes found in S. aureus. By employing a S. aureus strain encoding a constitutively active AIP receptor we show that the activity is mediated via agr. Subsequent cloning and heterologous expression of the S. schleiferi AIP in S. aureus demonstrated that this molecule was likely responsible for the inhibitory activity, and further proof was provided when pure synthetic S. schleiferi AIP was able to completely abolish agr induction of an S. aureus reporter strain. To assess impact on S. aureus virulence, we co-inoculated S. aureus and S. schleiferi in vivo in the Galleria mellonella wax moth larva, and found that expression of key S. aureus virulence factors was abrogated. Our data show that the S. aureus agr locus is highly responsive to other staphylococcal species suggesting that agr is an inter-species communication system. Based on these results we speculate that interactions between S. aureus and other colonizing staphylococci will significantly influence the ability of S. aureus to cause infection, and we propose that other staphylococci are potential sources of compounds that can be applied as anti-virulence therapy for combating S. aureus infections.
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Affiliation(s)
- Jaime Canovas
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Mara Baldry
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Martin S Bojer
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Paal S Andersen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of CopenhagenFrederiksberg, Denmark; Department of Microbiology and Infection Control, Statens Serum InstitutCopenhagen, Denmark
| | - Piotr K Grzeskowiak
- Center for Biopharmaceuticals and Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen Copenhagen, Denmark
| | - Marc Stegger
- Department of Microbiology and Infection Control, Statens Serum Institut Copenhagen, Denmark
| | - Peter Damborg
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Christian A Olsen
- Center for Biopharmaceuticals and Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen Copenhagen, Denmark
| | - Hanne Ingmer
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
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Biofilm production and beta-lactamic resistance in Brazilian Staphylococcus aureus isolates from bovine mastitis. Braz J Microbiol 2016; 48:118-124. [PMID: 27913076 PMCID: PMC5221365 DOI: 10.1016/j.bjm.2016.10.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 05/30/2016] [Indexed: 11/23/2022] Open
Abstract
Staphylococcus spp. play an important role in the etiology of bovine mastitis. Staphylococcus aureus is considered the most relevant species due to the production of virulence factors such as slime, which is required for biofilm formation. This study aimed to evaluate biofilm production and its possible relation to beta-lactamic resistance in 20 S. aureus isolates from bovine mastitic milk. The isolates were characterized by pheno-genotypic and MALDI TOF-MS assays and tested for genes such as icaA, icaD, bap, agr RNAIII, agr I, agr II, agr III, and agr IV, which are related to slime production and its regulation. Biofilm production in microplates was evaluated considering the intervals determined along the bacterial growth curve. In addition, to determine the most suitable time interval for biofilm analysis, scanning electron microscopy was performed. Furthermore, genes such as mecA and blaZ that are related to beta-lactamic resistance and oxacillin susceptibility were tested. All the studied isolates were biofilm producers and mostly presented icaA and icaD. The Agr type II genes were significantly prevalent. According to the SEM, gradual changes in the bacterial arrangement were observed during biofilm formation along the growth curve phases, and the peak was reached at the stationary phase. In this study, the penicillin resistance was related to the production of beta-lactamase, and the high minimal bactericidal concentration for cefoxitin was possibly associated with biofilm protection. Therefore, further studies are warranted to better understand biofilm formation, possibly contributing to our knowledge about bacterial resistance in vivo.
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Bronesky D, Wu Z, Marzi S, Walter P, Geissmann T, Moreau K, Vandenesch F, Caldelari I, Romby P. Staphylococcus aureus RNAIII and Its Regulon Link Quorum Sensing, Stress Responses, Metabolic Adaptation, and Regulation of Virulence Gene Expression. Annu Rev Microbiol 2016; 70:299-316. [PMID: 27482744 DOI: 10.1146/annurev-micro-102215-095708] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Staphylococcus aureus RNAIII is one of the main intracellular effectors of the quorum-sensing system. It is a multifunctional RNA that encodes a small peptide, and its noncoding parts act as antisense RNAs to regulate the translation and/or the stability of mRNAs encoding transcriptional regulators, major virulence factors, and cell wall metabolism enzymes. In this review, we explain how regulatory proteins and RNAIII are embedded in complex regulatory circuits to express virulence factors in a dynamic and timely manner in response to stress and environmental and metabolic changes.
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Affiliation(s)
- Delphine Bronesky
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
| | - Zongfu Wu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Stefano Marzi
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
| | - Philippe Walter
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
| | - Thomas Geissmann
- Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, Université de Lyon, INSERM U1111, CNRS UMR 5308, CIRI, 69008 Lyon, France
| | - Karen Moreau
- Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, Université de Lyon, INSERM U1111, CNRS UMR 5308, CIRI, 69008 Lyon, France
| | - François Vandenesch
- Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, Université de Lyon, INSERM U1111, CNRS UMR 5308, CIRI, 69008 Lyon, France
| | - Isabelle Caldelari
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
| | - Pascale Romby
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
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DNA microarray analysis of Staphylococcus aureus causing bloodstream infection: bacterial genes associated with mortality? Eur J Clin Microbiol Infect Dis 2016; 35:1285-95. [PMID: 27177754 DOI: 10.1007/s10096-016-2663-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/24/2016] [Indexed: 01/07/2023]
Abstract
Providing evidence for microbial genetic determinants' impact on outcome in Staphylococcus aureus bloodstream infections (SABSI) is challenging due to the complex and dynamic microbe-host interaction. Our recent population-based prospective study reported an association between the S. aureus clonal complex (CC) 30 genotype and mortality in SABSI patients. This follow-up investigation aimed to examine the genetic profiles of the SABSI isolates and test the hypothesis that specific genetic characteristics in S. aureus are associated with mortality. SABSI isolates (n = 305) and S. aureus CC30 isolates from asymptomatic nasal carriers (n = 38) were characterised by DNA microarray analysis and spa typing. Fisher's exact test, least absolute shrinkage and selection operator (LASSO) and elastic net regressions were performed to discern within four groups defined by patient outcome and characteristics. No specific S. aureus genetic determinants were found to be associated with mortality in SABSI patients. By applying LASSO and elastic net regressions, we found evidence suggesting that agrIII and cna were positively and setC (=selX) and seh were negatively associated with S. aureus CC30 versus non-CC30 isolates. The genes chp and sak, encoding immune evasion molecules, were found in higher frequencies in CC30 SABSI isolates compared to CC30 carrier isolates, indicating a higher virulence potential. In conclusion, no specific S. aureus genes were found to be associated with mortality by DNA microarray analysis and state-of-the-art statistical analyses. The next natural step is to test the hypothesis in larger samples with higher resolution methods, like whole genome sequencing.
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Mueller EA, Merriman JA, Schlievert PM. Toxic shock syndrome toxin-1, not α-toxin, mediated Bundaberg fatalities. Microbiology (Reading) 2015; 161:2361-2368. [DOI: 10.1099/mic.0.000196] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Elizabeth A. Mueller
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Joseph A. Merriman
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Patrick M. Schlievert
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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Khan BA, Yeh AJ, Cheung GYC, Otto M. Investigational therapies targeting quorum-sensing for the treatment of Staphylococcus aureus infections. Expert Opin Investig Drugs 2015; 24:689-704. [PMID: 25704585 DOI: 10.1517/13543784.2015.1019062] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
INTRODUCTION Antibiotic resistance is a serious global health concern for developed and developing nations. MRSA represents a particularly severe public health threat that is associated with high morbidity and mortality. The lack of novel antibiotics has led scientists to explore therapies targeting bacterial virulence mechanisms and virulence regulators, including those controlling cell-cell communication. AREAS COVERED The authors discuss the role of quorum-sensing in Staphylococcus aureus infections and components of the system that are being targeted using novel investigational drugs. In particular, the authors examine the role of the accessory gene regulator (Agr) system in virulence regulation of S. aureus pathogenesis. Finally, the authors present and compare natural and synthetic compounds that have been found to interfere with Agr functionality. EXPERT OPINION There is a great need to develop new therapeutic methods to combat S. aureus infections. These include anti-virulence therapies that target key global regulators involved with the establishment and propagation of infection. Several molecules have been found to interfere with S. aureus virulence regulation, especially those targeting the Agr quorum-sensing signaling molecule. These preliminary findings warrant further investigation and validation, with the goal of refining a compound that has broad-spectrum inhibitory effects on most S. aureus strains and Agr subtypes.
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Affiliation(s)
- Burhan A Khan
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories , 903 S. 4th St, 1/1110, Hamilton, MT 59840 , USA
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Arciola CR, Campoccia D, Ravaioli S, Montanaro L. Polysaccharide intercellular adhesin in biofilm: structural and regulatory aspects. Front Cell Infect Microbiol 2015; 5:7. [PMID: 25713785 PMCID: PMC4322838 DOI: 10.3389/fcimb.2015.00007] [Citation(s) in RCA: 274] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/14/2015] [Indexed: 01/05/2023] Open
Abstract
Staphylococcus aureus and Staphylococcus epidermidis are the leading etiologic agents of implant-related infections. Biofilm formation is the main pathogenetic mechanism leading to the chronicity and irreducibility of infections. The extracellular polymeric substances of staphylococcal biofilms are the polysaccharide intercellular adhesin (PIA), extracellular-DNA, proteins, and amyloid fibrils. PIA is a poly-β(1-6)-N-acetylglucosamine (PNAG), partially deacetylated, positively charged, whose synthesis is mediated by the icaADBC locus. DNA sequences homologous to ica locus are present in many coagulase-negative staphylococcal species, among which S. lugdunensis, however, produces a biofilm prevalently consisting of proteins. The product of icaA is an N-acetylglucosaminyltransferase that synthetizes PIA oligomers from UDP-N-acetylglucosamine. The product of icaD gives optimal efficiency to IcaA. The product of icaC is involved in the externalization of the nascent polysaccharide. The product of icaB is an N-deacetylase responsible for the partial deacetylation of PIA. The expression of ica locus is affected by environmental conditions. In S. aureus and S. epidermidis ica-independent alternative mechanisms of biofilm production have been described. S. epidermidis and S. aureus undergo to a phase variation for the biofilm production that has been ascribed, in turn, to the transposition of an insertion sequence in the icaC gene or to the expansion/contraction of a tandem repeat naturally harbored within icaC. A role is played by the quorum sensing system, which negatively regulates biofilm formation, favoring the dispersal phase that disseminates bacteria to new infection sites. Interfering with the QS system is a much debated strategy to combat biofilm-related infections. In the search of vaccines against staphylococcal infections deacetylated PNAG retained on the surface of S. aureus favors opsonophagocytosis and is a potential candidate for immune-protection.
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Affiliation(s)
- Carla Renata Arciola
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute Bologna, Italy ; Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna Bologna, Italy
| | - Davide Campoccia
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute Bologna, Italy
| | - Stefano Ravaioli
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute Bologna, Italy ; Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna Bologna, Italy
| | - Lucio Montanaro
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute Bologna, Italy ; Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna Bologna, Italy
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Nitzan M, Fechter P, Peer A, Altuvia Y, Bronesky D, Vandenesch F, Romby P, Biham O, Margalit H. A defense-offense multi-layered regulatory switch in a pathogenic bacterium. Nucleic Acids Res 2015; 43:1357-69. [PMID: 25628364 PMCID: PMC4330369 DOI: 10.1093/nar/gkv001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells adapt to environmental changes by efficiently adjusting gene expression programs. Staphylococcus aureus, an opportunistic pathogenic bacterium, switches between defensive and offensive modes in response to quorum sensing signal. We identified and studied the structural characteristics and dynamic properties of the core regulatory circuit governing this switch by deterministic and stochastic computational methods, as well as experimentally. This module, termed here Double Selector Switch (DSS), comprises the RNA regulator RNAIII and the transcription factor Rot, defining a double-layered switch involving both transcriptional and post-transcriptional regulations. It coordinates the inverse expression of two sets of target genes, immuno-modulators and exotoxins, expressed during the defensive and offensive modes, respectively. Our computational and experimental analyses show that the DSS guarantees fine-tuned coordination of the inverse expression of its two gene sets, tight regulation, and filtering of noisy signals. We also identified variants of this circuit in other bacterial systems, suggesting it is used as a molecular switch in various cellular contexts and offering its use as a template for an effective switching device in synthetic biology studies.
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Affiliation(s)
- Mor Nitzan
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
| | - Pierre Fechter
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg F-67084, France
| | - Asaf Peer
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
| | - Yael Altuvia
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
| | - Delphine Bronesky
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg F-67084, France
| | - François Vandenesch
- CIRI, International Center for Infectiology Research,Lyon, France Inserm, U1111, Lyon, France École Normale Supérieure de Lyon, Lyon, France Université Lyon 1, Lyon, France CNRS, UMR5308, Lyon, France
| | - Pascale Romby
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg F-67084, France
| | - Ofer Biham
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
| | - Hanah Margalit
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
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39
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Arciola CR, Campoccia D, Ravaioli S, Montanaro L. Polysaccharide intercellular adhesin in biofilm: structural and regulatory aspects. Front Cell Infect Microbiol 2015. [PMID: 25713785 DOI: 10.3389/fcimb.2015.00007/bibtex] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023] Open
Abstract
Staphylococcus aureus and Staphylococcus epidermidis are the leading etiologic agents of implant-related infections. Biofilm formation is the main pathogenetic mechanism leading to the chronicity and irreducibility of infections. The extracellular polymeric substances of staphylococcal biofilms are the polysaccharide intercellular adhesin (PIA), extracellular-DNA, proteins, and amyloid fibrils. PIA is a poly-β(1-6)-N-acetylglucosamine (PNAG), partially deacetylated, positively charged, whose synthesis is mediated by the icaADBC locus. DNA sequences homologous to ica locus are present in many coagulase-negative staphylococcal species, among which S. lugdunensis, however, produces a biofilm prevalently consisting of proteins. The product of icaA is an N-acetylglucosaminyltransferase that synthetizes PIA oligomers from UDP-N-acetylglucosamine. The product of icaD gives optimal efficiency to IcaA. The product of icaC is involved in the externalization of the nascent polysaccharide. The product of icaB is an N-deacetylase responsible for the partial deacetylation of PIA. The expression of ica locus is affected by environmental conditions. In S. aureus and S. epidermidis ica-independent alternative mechanisms of biofilm production have been described. S. epidermidis and S. aureus undergo to a phase variation for the biofilm production that has been ascribed, in turn, to the transposition of an insertion sequence in the icaC gene or to the expansion/contraction of a tandem repeat naturally harbored within icaC. A role is played by the quorum sensing system, which negatively regulates biofilm formation, favoring the dispersal phase that disseminates bacteria to new infection sites. Interfering with the QS system is a much debated strategy to combat biofilm-related infections. In the search of vaccines against staphylococcal infections deacetylated PNAG retained on the surface of S. aureus favors opsonophagocytosis and is a potential candidate for immune-protection.
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Affiliation(s)
- Carla Renata Arciola
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute Bologna, Italy ; Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna Bologna, Italy
| | - Davide Campoccia
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute Bologna, Italy
| | - Stefano Ravaioli
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute Bologna, Italy ; Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna Bologna, Italy
| | - Lucio Montanaro
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute Bologna, Italy ; Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna Bologna, Italy
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40
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Hunt K, Butler F, Jordan K. Factors affecting staphylococcal enterotoxin Cbovine production in milk. Int Dairy J 2014. [DOI: 10.1016/j.idairyj.2014.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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41
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Hartmann T, Baronian G, Nippe N, Voss M, Schulthess B, Wolz C, Eisenbeis J, Schmidt-Hohagen K, Gaupp R, Sunderkötter C, Beisswenger C, Bals R, Somerville GA, Herrmann M, Molle V, Bischoff M. The catabolite control protein E (CcpE) affects virulence determinant production and pathogenesis of Staphylococcus aureus. J Biol Chem 2014; 289:29701-11. [PMID: 25193664 DOI: 10.1074/jbc.m114.584979] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Carbon metabolism and virulence determinant production are often linked in pathogenic bacteria, and several regulatory elements have been reported to mediate this linkage in Staphylococcus aureus. Previously, we described a novel protein, catabolite control protein E (CcpE) that functions as a regulator of the tricarboxylic acid cycle. Here we demonstrate that CcpE also regulates virulence determinant biosynthesis and pathogenesis. Specifically, deletion of ccpE in S. aureus strain Newman revealed that CcpE affects transcription of virulence factors such as capA, the first gene in the capsule biosynthetic operon; hla, encoding α-toxin; and psmα, encoding the phenol-soluble modulin cluster α. Electrophoretic mobility shift assays demonstrated that CcpE binds to the hla promoter. Mice challenged with S. aureus strain Newman or its isogenic ΔccpE derivative revealed increased disease severity in the ΔccpE mutant using two animal models; an acute lung infection model and a skin infection model. Complementation of the mutant with the ccpE wild-type allele restored all phenotypes, demonstrating that CcpE is negative regulator of virulence in S. aureus.
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Affiliation(s)
- Torsten Hartmann
- From the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany
| | - Grégory Baronian
- the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université Montpellier 2, CNRS, UMR 5235, 34090 Montpellier, France
| | - Nadine Nippe
- the Institute of Immunology, University of Münster, 48149 Münster, Germany
| | - Meike Voss
- the Department of Internal Medicine V-Pulmonology, Allergology and Critical Care Medicine, Saarland University Medical Centre, 66421 Homburg/Saar, Germany
| | - Bettina Schulthess
- the Institute of Medical Microbiology, University of Zürich, 8006 Zürich, Switzerland
| | - Christiane Wolz
- the Institute of Medical Microbiology and Hygiene, University Hospital of Tübingen, 72076 Tübingen, Germany
| | - Janina Eisenbeis
- From the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany
| | - Kerstin Schmidt-Hohagen
- the Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Rosmarie Gaupp
- From the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany
| | - Cord Sunderkötter
- the Department of Dermatology, University of Münster, 48149 Münster, Germany, and
| | - Christoph Beisswenger
- the Department of Internal Medicine V-Pulmonology, Allergology and Critical Care Medicine, Saarland University Medical Centre, 66421 Homburg/Saar, Germany
| | - Robert Bals
- the Department of Internal Medicine V-Pulmonology, Allergology and Critical Care Medicine, Saarland University Medical Centre, 66421 Homburg/Saar, Germany
| | - Greg A Somerville
- the School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, Nebraska 68583-0903
| | - Mathias Herrmann
- From the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany
| | - Virginie Molle
- the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université Montpellier 2, CNRS, UMR 5235, 34090 Montpellier, France
| | - Markus Bischoff
- From the Institute of Medical Microbiology and Hygiene, University of Saarland, 66421 Homburg/Saar, Germany,
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42
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Chen J, Yoong P, Ram G, Torres VJ, Novick RP. Single-copy vectors for integration at the SaPI1 attachment site for Staphylococcus aureus. Plasmid 2014; 76:1-7. [PMID: 25192956 DOI: 10.1016/j.plasmid.2014.08.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 08/15/2014] [Accepted: 08/17/2014] [Indexed: 10/24/2022]
Abstract
We have previously reported the construction of Staphylococcus aureus integration vectors based on the staphylococcal pathogenicity island 1 (SaPI1) site-specific recombination system. These are shuttle vectors that can be propagated in Escherichia coli, which allows for standard DNA manipulations. In S. aureus, these vectors are temperature-sensitive and can only be maintained at non-permissive (42 °C) temperatures by integrating into the chromosome. However, most S. aureus strains are sensitive to prolonged incubations at higher temperatures and will rapidly accumulate mutations, making the use of temperature-sensitive integration vectors impractical for single-copy applications. Here we describe improved versions of these vectors, which are maintained only in single-copy at the SaPI1 attachment site. In addition, we introduce several additional cassettes containing resistance markers, expanding the versatility of integrant selection, especially in strains that are resistant to multiple antibiotics.
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Affiliation(s)
- John Chen
- Skirball Institute Program in Molecular Pathogenesis and Departments of Microbiology and Medicine, New York University Medical Center, New York, NY 10016, USA.
| | - Pauline Yoong
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Geeta Ram
- Skirball Institute Program in Molecular Pathogenesis and Departments of Microbiology and Medicine, New York University Medical Center, New York, NY 10016, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Richard P Novick
- Skirball Institute Program in Molecular Pathogenesis and Departments of Microbiology and Medicine, New York University Medical Center, New York, NY 10016, USA.
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Mairpady Shambat S, Haggar A, Vandenesch F, Lina G, van Wamel WJB, Arakere G, Svensson M, Norrby-Teglund A. Levels of alpha-toxin correlate with distinct phenotypic response profiles of blood mononuclear cells and with agr background of community-associated Staphylococcus aureus isolates. PLoS One 2014; 9:e106107. [PMID: 25166615 PMCID: PMC4148398 DOI: 10.1371/journal.pone.0106107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 07/28/2014] [Indexed: 11/18/2022] Open
Abstract
Epidemiological studies of Staphylococcus aureus have shown a relation between certain clones and the presence of specific virulence genes, but how this translates into virulence-associated functional responses is not fully elucidated. Here we addressed this issue by analyses of community-acquired S. aureus strains characterized with respect to antibiotic resistance, ST types, agr types, and virulence gene profiles. Supernatants containing exotoxins were prepared from overnight bacterial cultures, and tested in proliferation assays using human peripheral blood mononuclear cells (PBMC). The strains displayed stable phenotypic response profiles, defined by either a proliferative or cytotoxic response. Although, virtually all strains elicited superantigen-mediated proliferative responses, the strains with a cytotoxic profile induced proliferation only in cultures with the most diluted supernatants. This indicated that the superantigen-response was masked by a cytotoxic effect which was also confirmed by flow cytometry analysis. The cytotoxic supernatants contained significantly higher levels of α-toxin than did the proliferative supernatants. Addition of α-toxin to supernatants characterized as proliferative switched the response into cytotoxic profiles. In contrast, no effect of Panton Valentine Leukocidin, δ-toxin or phenol soluble modulin α-3 was noted in the proliferative assay. Furthermore, a significant association between agr type and phenotypic profile was found, where agrII and agrIII strains had predominantly a proliferative profile whereas agrI and IV strains had a predominantly cytotoxic profile. The differential response profiles associated with specific S. aureus strains with varying toxin production could possibly have an impact on disease manifestations, and as such may reflect specific pathotypes.
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Affiliation(s)
| | - Axana Haggar
- Karolinska Institutet, Centre for Infectious Medicine, Stockholm, Sweden
| | - Francois Vandenesch
- CIRI, International Center for Infectiology Research, LabEx Ecofect, Université Lyon 1, Inserm U1111, Ecole Normale Supérieure de Lyon, CNRS UMR5308, Centre National de Référence des Staphylocoques, Hospices civils de Lyon, Lyon, France
| | - Gerard Lina
- CIRI, International Center for Infectiology Research, LabEx Ecofect, Université Lyon 1, Inserm U1111, Ecole Normale Supérieure de Lyon, CNRS UMR5308, Centre National de Référence des Staphylocoques, Hospices civils de Lyon, Lyon, France
| | - Willem J. B. van Wamel
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Centre, Rotterdam, Netherlands
| | - Gayathri Arakere
- Society for Innovation and Development, Indian Institute of Science Campus, Bangalore, India
| | - Mattias Svensson
- Karolinska Institutet, Centre for Infectious Medicine, Stockholm, Sweden
| | - Anna Norrby-Teglund
- Karolinska Institutet, Centre for Infectious Medicine, Stockholm, Sweden
- * E-mail:
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Multi-virulence-locus sequence typing of Staphylococcus lugdunensis generates results consistent with a clonal population structure and is reliable for epidemiological typing. J Clin Microbiol 2014; 52:3624-32. [PMID: 25078912 DOI: 10.1128/jcm.01370-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Staphylococcus lugdunensis is an emergent virulent coagulase-negative staphylococcus responsible for severe infections similar to those caused by Staphylococcus aureus. To understand its potentially pathogenic capacity and have further detailed knowledge of the molecular traits of this organism, 93 isolates from various geographic origins were analyzed by multi-virulence-locus sequence typing (MVLST), targeting seven known or putative virulence-associated loci (atlLR2, atlLR3, hlb, isdJ, SLUG_09050, SLUG_16930, and vwbl). The polymorphisms of the putative virulence-associated loci were moderate and comparable to those of the housekeeping genes analyzed by multilocus sequence typing (MLST). However, the MVLST scheme generated 43 virulence types (VTs) compared to 20 sequence types (STs) based on MLST, indicating that MVLST was significantly more discriminating (Simpson's index [D], 0.943). No hypervirulent lineage or cluster specific to carriage strains was defined. The results of multilocus sequence analysis of known and putative virulence-associated loci are consistent with a clonal population structure for S. lugdunensis, suggesting a coevolution of these genes with housekeeping genes. Indeed, the nonsynonymous to synonymous evolutionary substitutions (dN/dS) ratio, the Tajima's D test, and Single-likelihood ancestor counting (SLAC) analysis suggest that all virulence-associated loci were under negative selection, even atlLR2 (AtlL protein) and SLUG_16930 (FbpA homologue), for which the dN/dS ratios were higher. In addition, this analysis of virulence-associated loci allowed us to propose a trilocus sequence typing scheme based on the intragenic regions of atlLR3, isdJ, and SLUG_16930, which is more discriminant than MLST for studying short-term epidemiology and further characterizing the lineages of the rare but highly pathogenic S. lugdunensis.
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Kim MK, Drescher K, Pak OS, Bassler BL, Stone HA. Filaments in curved streamlines: Rapid formation of Staphylococcus aureus biofilm streamers. NEW JOURNAL OF PHYSICS 2014; 16:065024. [PMID: 25484614 PMCID: PMC4255984 DOI: 10.1088/1367-2630/16/6/065024] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Biofilms are surface-associated conglomerates of bacteria that are highly resistant to antibiotics. These bacterial communities can cause chronic infections in humans by colonizing, for example, medical implants, heart valves, or lungs. Staphylococcus aureus, a notorious human pathogen, causes some of the most common biofilm-related infections. Despite the clinical importance of S. aureus biofilms, it remains mostly unknown how physical effects, in particular flow, and surface structure influence biofilm dynamics. Here we use model microfluidic systems to investigate how environmental factors, such as surface geometry, surface chemistry, and fluid flow affect biofilm development in S. aureus. We discovered that S. aureus rapidly forms flow-induced, filamentous biofilm streamers, and furthermore if surfaces are coated with human blood plasma, streamers appear within minutes and clog the channels more rapidly than if the channels are uncoated. To understand how biofilm streamer filaments reorient in flows with curved streamlines to bridge the distances between corners, we developed a mathematical model based on resistive force theory of slender filaments. Understanding physical aspects of biofilm formation in S. aureus may lead to new approaches for interrupting biofilm formation of this pathogen.
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Affiliation(s)
| | - Knut Drescher
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - On Shun Pak
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544
| | - Bonnie L. Bassler
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
- Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Howard A. Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544
- Corresponding author:
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46
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Purrello S, Daum R, Edwards G, Lina G, Lindsay J, Peters G, Stefani S. Meticillin-resistant Staphylococcus aureus (MRSA) update: New insights into bacterial adaptation and therapeutic targets. J Glob Antimicrob Resist 2014; 2:61-69. [DOI: 10.1016/j.jgar.2014.02.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/06/2014] [Indexed: 12/23/2022] Open
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Whole-genome sequencing for high-resolution investigation of methicillin-resistant Staphylococcus aureus epidemiology and genome plasticity. J Clin Microbiol 2014; 52:2787-96. [PMID: 24850346 DOI: 10.1128/jcm.00759-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infections pose a major challenge in health care, yet the limited heterogeneity within this group hinders molecular investigations of related outbreaks. Pulsed-field gel electrophoresis (PFGE) has been the gold standard approach but is impractical for many clinical laboratories and is often replaced with PCR-based methods. Regardless, both approaches can prove problematic for identifying subclonal outbreaks. Here, we explore the use of whole-genome sequencing for clinical laboratory investigations of MRSA molecular epidemiology. We examine the relationships of 44 MRSA isolates collected over a period of 3 years by using whole-genome sequencing and two PCR-based methods, multilocus variable-number tandem-repeat analysis (MLVA) and spa typing. We find that MLVA offers higher resolution than spa typing, as it resolved 17 versus 12 discrete isolate groups, respectively. In contrast, whole-genome sequencing reproducibly cataloged genomic variants (131,424 different single nucleotide polymorphisms and indels across the strain collection) that uniquely identified each MRSA clone, recapitulating those groups but enabling higher-resolution phylogenetic inferences of the epidemiological relationships. Importantly, whole-genome sequencing detected a significant number of variants, thereby distinguishing between groups that were considered identical by both spa typing (minimum, 1,124 polymorphisms) and MLVA (minimum, 193 polymorphisms); this suggests that these more conventional approaches can lead to false-positive identification of outbreaks due to inappropriate grouping of genetically distinct strains. An analysis of the distribution of variants across the MRSA genome reveals 47 mutational hot spots (comprising ∼ 2.5% of the genome) that account for 23.5% of the observed polymorphisms, and the use of this selected data set successfully recapitulates most epidemiological relationships in this pathogen group.
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Salgado-Pabón W, Herrera A, Vu BG, Stach CS, Merriman JA, Spaulding AR, Schlievert PM. Staphylococcus aureus β-toxin production is common in strains with the β-toxin gene inactivated by bacteriophage. J Infect Dis 2014; 210:784-92. [PMID: 24620023 DOI: 10.1093/infdis/jiu146] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Staphylococcus aureus causes life-threatening infections, including infective endocarditis, sepsis, and pneumonia. β-toxin is a sphingomyelinase encoded for by virtually all S. aureus strains and exhibits human immune cell cytotoxicity. The toxin enhances S. aureus phenol-soluble modulin activity, and its activity is enhanced by superantigens. The bacteriophage φSa3 inserts into the β-toxin gene in human strains, inactivating it in the majority of S. aureus clonal groups. Hence, most strains are reported not to secrete β-toxin. METHODS This dynamic was investigated by examining β-toxin production by multiple clonal groups of S. aureus, both in vitro and in vivo during infections in rabbit models of infective endocarditis, sepsis, and pneumonia. RESULTS β-toxin phenotypic variants are common among strains containing φSa3. In vivo, φSa3 is differentially induced in heart vegetations, kidney abscesses, and ischemic liver compared to spleen and blood, and in vitro growth in liquid culture. Furthermore, in pneumonia, wild-type β-toxin production leads to development of large caseous lesions, and in infective endocarditis, increases the size of pathognomonic vegetations. CONCLUSIONS This study demonstrates the dynamic interaction between S. aureus and the infected host, where φSa3 serves as a regulator of virulence gene expression, and increased fitness and virulence in new environments.
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Affiliation(s)
- Wilmara Salgado-Pabón
- Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City
| | - Alfa Herrera
- Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City
| | - Bao G Vu
- Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City
| | - Christopher S Stach
- Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City
| | - Joseph A Merriman
- Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City
| | - Adam R Spaulding
- Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City
| | - Patrick M Schlievert
- Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City
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Grinholc M, Nakonieczna J, Negri A, Rapacka-Zdonczyk A, Motyka A, Fila G, Kurlenda J, Leibner-Ciszak J, Otto M, Bielawski KP. The agr function and polymorphism: impact on Staphylococcus aureus susceptibility to photoinactivation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2013; 129:100-7. [PMID: 24211295 DOI: 10.1016/j.jphotobiol.2013.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/07/2013] [Accepted: 10/10/2013] [Indexed: 11/18/2022]
Abstract
Staphylococcus aureus is an important human pathogen that causes healthcare-associated and community-acquired infections. Moreover, the growing prevalence of multiresistant strains requires the development of alternative methods to antibiotic therapy. One effective therapeutic option may be antimicrobial photodynamic inactivation (aPDI). Recently, S. aureus strain-dependent response to PDI was demonstrated, although the mechanism underlying this phenomenon remains unexplained. The aim of the current study was to investigate statistically relevant correlations between the functionality and polymorphisms of agr gene determined for 750 methicillin-susceptible and methicillin-resistant S. aureus strains and their responses to photodynamic inactivation using protoporphyrin IX. An AluI and RsaI digestion of the agr gene PCR product revealed existing correlations between the determined digestion profiles (designations used for the first time) and the PDI response. Moreover, the functionality of the agr system affected S. aureus susceptibility to PDI. Based on our results, we conclude that the agr gene may be a genetic factor affecting the strain dependent response to PDI.
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Affiliation(s)
- Mariusz Grinholc
- Laboratory of Molecular Diagnostics, Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Kladki 24, 80-822 Gdansk, Poland.
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Gray B, Hall P, Gresham H. Targeting agr- and agr-Like quorum sensing systems for development of common therapeutics to treat multiple gram-positive bacterial infections. SENSORS 2013; 13:5130-66. [PMID: 23598501 PMCID: PMC3673130 DOI: 10.3390/s130405130] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 04/06/2013] [Accepted: 04/12/2013] [Indexed: 12/13/2022]
Abstract
Invasive infection by the Gram-positive pathogen Staphylococcus aureus is controlled by a four gene operon, agr that encodes a quorum sensing system for the regulation of virulence. While agr has been well studied in S. aureus, the contribution of agr homologues and analogues in other Gram-positive pathogens is just beginning to be understood. Intriguingly, other significant human pathogens, including Clostridium perfringens, Listeria monocytogenes, and Enterococcus faecalis contain agr or analogues linked to virulence. Moreover, other significant human Gram-positive pathogens use peptide based quorum sensing systems to establish or maintain infection. The potential for commonality in aspects of these signaling systems across different species raises the prospect of identifying therapeutics that could target multiple pathogens. Here, we review the status of research into these agr homologues, analogues, and other peptide based quorum sensing systems in Gram-positive pathogens as well as the potential for identifying common pathways and signaling mechanisms for therapeutic discovery.
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Affiliation(s)
- Brian Gray
- Department of Pharmaceutical Sciences, College of Pharmacy/MRF 208, MSC09 5360, University of New Mexico, Albuquerque, NM 87131-0001, USA; E-Mail:
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, NM 87108, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-505-265-1711 (ext. 2841)
| | - Pamela Hall
- Department of Pharmaceutical Sciences, College of Pharmacy/MRF 208, MSC09 5360, University of New Mexico, Albuquerque, NM 87131-0001, USA; E-Mail:
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, NM 87108, USA
| | - Hattie Gresham
- Research Service, New Mexico Veterans Affairs Medical Center, Albuquerque, NM 87108, USA
- Department of Internal Medicine, Division of Infectious Diseases, University of New Mexico, Albuquerque, NM 87131, USA; E-Mail:
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