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Saleh NM, Sudan ESF, Mohamed SH, El-Shahed MM, Hamouda RE, El-Gendy AO, Farag AA. Pathogen Partnerships or Power Struggles? Pseudomonas aeruginosa, and Staphylococcus aureus Dynamics in Cystic Fibrosis. Curr Microbiol 2025; 82:236. [PMID: 40198369 DOI: 10.1007/s00284-025-04167-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 02/26/2025] [Indexed: 04/10/2025]
Abstract
Cystic fibrosis (CF) is a polymicrobial infection characterized by interactions among various bacterial species that affect one another's cohabitation. The investigation of interspecies interactions in dual infections is essential to understand their reaction in the environment better and assist in the development of treatment regimens and innovative disease control approaches. Our hypothesis posits that co-infection interactions promote the adaptation of Staphylococcus aureus and Pseudomonas aeruginosa, potentially leading to synergistic action. To explore this, we examined dual-species interactions in co-isolated pairs of these organisms from Egyptian CF patients using laboratory media and artificial sputum media (ASM). Based on demographic data, 82 collected bacterial isolates from single, dual, and triple cultures were identified from 50 enrolled patients. In the interaction of the pairs in mimic media, P. aeruginosa exo-products significantly enhanced the biofilm formation and growth of S. aureus. Conversely, S. aureus did not inhibit P. aeruginosa biofilm formation. Furthermore, the biofilm mode of dual-organism growth provides protection in the CF context, as bacterial biofilms can withstand much higher antimicrobial levels compared to planktonically grown bacteria. Additionally, key biofilm genes regulated by quorum sensing were differentially expressed in both species in an isolate-dependent manner, highlighting their significant role in coexistence dual-species biofilm coexistence. In conclusion, our study illuminates the competitive and cooperative interactions between these two pathogens, which impact their coexistence and encourage biofilm production. This, in turn, accelerates disease progression and compromises patient health.
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Affiliation(s)
- Neveen M Saleh
- Department of Microbiology, Egyptian Drug Authority (Former National Organization for Drug Control and Research (NODCAR)), Giza, Egypt.
- College of Public Health, University of Nebraska Medical Center (UNMC), Omaha, United States.
| | - Esraa S F Sudan
- Department of Microbiology, Egyptian Drug Authority (Former National Organization for Drug Control and Research (NODCAR)), Giza, Egypt
| | - Sara H Mohamed
- Department of Microbiology, Egyptian Drug Authority (Former National Organization for Drug Control and Research (NODCAR)), Giza, Egypt
| | - Maram M El-Shahed
- Department of Microbiology, Egyptian Drug Authority (Former National Organization for Drug Control and Research (NODCAR)), Giza, Egypt
| | - Reda E Hamouda
- Department of Animal Production Systems Research, Animal Production Research Institute, Agricultural Research Center, Ministry of Agriculture and Land Reclamation, Giza, Egypt
| | - Ahmed Osama El-Gendy
- Microbiology and Immunology Department, Faculty of Pharmacy, Beni-Suef University, Beni Suef, 62514, Egypt
| | - Ahmed A Farag
- Microbiology and Immunology Department, Faculty of Pharmacy, Beni-Suef University, Beni Suef, 62514, Egypt
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2
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Patel H, Rawat S. A genetic regulatory see-saw of biofilm and virulence in MRSA pathogenesis. Front Microbiol 2023; 14:1204428. [PMID: 37434702 PMCID: PMC10332168 DOI: 10.3389/fmicb.2023.1204428] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 05/30/2023] [Indexed: 07/13/2023] Open
Abstract
Staphylococcus aureus is one of the most common opportunistic human pathogens causing several infectious diseases. Ever since the emergence of the first methicillin-resistant Staphylococcus aureus (MRSA) strain decades back, the organism has been a major cause of hospital-acquired infections (HA-MRSA). The spread of this pathogen across the community led to the emergence of a more virulent subtype of the strain, i.e., Community acquired Methicillin resistant Staphylococcus aureus (CA-MRSA). Hence, WHO has declared Staphylococcus aureus as a high-priority pathogen. MRSA pathogenesis is remarkable because of the ability of this "superbug" to form robust biofilm both in vivo and in vitro by the formation of polysaccharide intercellular adhesin (PIA), extracellular DNA (eDNA), wall teichoic acids (WTAs), and capsule (CP), which are major components that impart stability to a biofilm. On the other hand, secretion of a diverse array of virulence factors such as hemolysins, leukotoxins, enterotoxins, and Protein A regulated by agr and sae two-component systems (TCS) aids in combating host immune response. The up- and downregulation of adhesion genes involved in biofilm formation and genes responsible for synthesizing virulence factors during different stages of infection act as a genetic regulatory see-saw in the pathogenesis of MRSA. This review provides insight into the evolution and pathogenesis of MRSA infections with a focus on genetic regulation of biofilm formation and virulence factors secretion.
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Affiliation(s)
| | - Seema Rawat
- Microbiology Laboratory, School of Life Sciences, Central University of Gujarat, Gandhinagar, Gujarat, India
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3
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Abstract
SarA, a transcriptional regulator of Staphylococcus aureus, is a major global regulatory system that coordinates the expression of target genes involved in its pathogenicity. Various studies have identified a large number of SarA target genes, but an in-depth characterization of the sarA regulon, including small regulatory RNAs (sRNAs), has not yet been done. In this study, we utilized transcriptome sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq) to determine a comprehensive list of SarA-regulated targets, including both mRNAs and sRNAs. RNA-Seq analysis indicated 390 mRNAs and 51 sRNAs differentially expressed in a ΔsarA mutant, while ChIP-Seq revealed 354 mRNAs and 55 sRNA targets in the S. aureus genome. We confirmed the authenticity of several novel SarA targets by Northern blotting and electrophoretic mobility shift assays. Among them, we characterized repression of sprG2, a gene that encodes the toxin of a type I toxin-antitoxin system, indicating a multilayer lockdown of toxin expression by both SarA and its cognate antitoxin, SprF2. Finally, a novel SarA consensus DNA binding sequence was generated using the upstream promoter sequences of 15 novel SarA-regulated sRNA targets. A genome-wide scan with a deduced SarA motif enabled the discovery of new potential SarA target genes which were not identified in our RNA-Seq and ChIP-Seq analyses. The strength of this new consensus was confirmed with one predicted sRNA target. The RNA-Seq and ChIP-Seq combinatory analysis gives a snapshot of the regulation, whereas bioinformatic analysis reveals a permanent view of targets based on sequence. Altogether these experimental and in silico methodologies are effective to characterize transcriptional factor (TF) regulons and functions. IMPORTANCEStaphylococcus aureus, a commensal and opportunist pathogen, is responsible for a large number of human and animal infections, from benign to severe. Gene expression adaptation during infection requires a complex network of regulators, including transcriptional factors (TF) and sRNAs. TF SarA influences virulence, metabolism, biofilm formation, and resistance to some antibiotics. SarA directly regulates expression of around 20 mRNAs and a few sRNAs. Here, we combined high-throughput expression screening methods combined with binding assays and bioinformatics for an in-depth investigation of the SarA regulon. This combinatory approach allowed the identification of 85 unprecedented mRNAs and sRNAs targets, with at least 14 being primary. Among novel SarA direct targets, we characterized repression of sprG2, a gene that encodes the toxin of a toxin-antitoxin system, indicating a multilayer lockdown of toxin expression by both SarA and its cognate antitoxin, SprF2.
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Yoon DJ, Nguyen C, Bagood MD, Fregoso DR, Yang HY, Medina Lopez AI, Crawford RW, Tran J, Isseroff RR. Topical Fluoxetine as a Potential Nonantibiotic Adjunctive Therapy for Infected Wounds. J Invest Dermatol 2020; 141:1608-1612.e3. [PMID: 33338500 DOI: 10.1016/j.jid.2020.11.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 10/13/2020] [Accepted: 11/10/2020] [Indexed: 01/15/2023]
Affiliation(s)
- Daniel J Yoon
- Department of Dermatology, University of California, Davis, Sacramento, California, USA
| | - Chuong Nguyen
- Department of Dermatology, University of California, Davis, Sacramento, California, USA
| | - Michelle D Bagood
- Department of Dermatology, University of California, Davis, Sacramento, California, USA
| | - Daniel R Fregoso
- Department of Dermatology, University of California, Davis, Sacramento, California, USA
| | - Hsin-Ya Yang
- Department of Dermatology, University of California, Davis, Sacramento, California, USA
| | - Andrea I Medina Lopez
- Department of Dermatology, University of California, Davis, Sacramento, California, USA
| | - Robert W Crawford
- Department of Biological Sciences, California State University, Sacramento, Sacramento, California, USA
| | - Jennifer Tran
- Department of Biological Sciences, California State University, Sacramento, Sacramento, California, USA
| | - R Rivkah Isseroff
- Department of Dermatology, University of California, Davis, Sacramento, California, USA.
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5
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Häffner N, Bär J, Dengler Haunreiter V, Mairpady Shambat S, Seidl K, Crosby HA, Horswill AR, Zinkernagel AS. Intracellular Environment and agr System Affect Colony Size Heterogeneity of Staphylococcus aureus. Front Microbiol 2020; 11:1415. [PMID: 32695082 PMCID: PMC7339952 DOI: 10.3389/fmicb.2020.01415] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 06/02/2020] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus causes chronic and relapsing infections, which may be difficult to treat. So-called small colony variants (SCVs) have been associated with chronic infections and their occurrence has been shown to increase under antibiotic pressure, low pH and intracellular localization. In clinics, S. aureus isolated from invasive infections often show a dysfunction in the accessory gene regulator (agr), a major virulence regulatory system in S. aureus. To assess whether intracellular environment and agr function influence SCV formation, an infection model was established using lung epithelial cells and skin fibroblasts. This allowed analyzing intracellular survival and localization of a panel of S. aureus wild type strains and their isogenic agr knock out mutants as well as a natural dysfunctional agr strain by confocal laser scanning microscopy (CLSM). Furthermore, bacterial colonies were quantified after 1, 3, and 5 days of intracellular survival by time-lapse analysis to determine kinetics of colony appearance and SCV formation. Here, we show that S. aureus strains with an agr knock out predominantly resided in a neutral environment, whereas wild type strains and an agr complemented strain resided in an acidic environment. S. aureus agr mutants derived from an intracellular environment showed a higher percentage of SCVs as compared to their corresponding wild type strains. Neutralizing acidic phagolysosomes with chloroquine resulted in a significant reduction of SCVs in S. aureus wild type strain 6850, but not in its agr mutant indicating a pH dependent formation of SCVs in the wild type strain. The in-depth understanding of the interplay between intracellular persistence, agr function and pH should help to identify new therapeutic options facilitating the treatment of chronic S. aureus infections in the future.
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Affiliation(s)
- Nicola Häffner
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Julian Bär
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Vanina Dengler Haunreiter
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Kati Seidl
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Heidi A Crosby
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Veterans Affairs Eastern Colorado Health Care System, Denver, CO, United States
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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6
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Zhang D, Gan RY, Zhang JR, Farha AK, Li HB, Zhu F, Wang XH, Corke H. Antivirulence properties and related mechanisms of spice essential oils: A comprehensive review. Compr Rev Food Sci Food Saf 2020; 19:1018-1055. [PMID: 33331691 DOI: 10.1111/1541-4337.12549] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 01/09/2020] [Accepted: 01/30/2020] [Indexed: 12/19/2022]
Abstract
In recent decades, reduced antimicrobial effectiveness, increased bacterial infection, and newly emerged microbial resistance have become global public issues, leading to an urgent need to find effective strategies to counteract these problems. Strategies targeting bacterial virulence factors rather than bacterial survival have attracted increasing interest, since the modulation of virulence factors may prevent the development of drug resistance in bacteria. Spices are promising natural sources of antivirulence compounds owing to their wide availability, diverse antivirulence phytochemical constituents, and generally favorable safety profiles. Essential oils are the predominant and most important antivirulence components of spices. This review addresses the recent efforts of using spice essential oils to inhibit main bacterial virulence traits, including the quorum sensing system, biofilm formation, motility, and toxin production, with an intensive discussion of related mechanisms. We hope that this review can provide a better understanding of the antivirulence properties of spice essential oils, which have the potential to be used as antibiotic alternatives by targeting bacterial virulence.
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Affiliation(s)
- Dan Zhang
- Department of Food Science & Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Ren-You Gan
- Department of Food Science & Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China.,Research Center for Plants and Human Health, Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, China
| | - Jia-Rong Zhang
- Department of Food Science & Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Arakkaveettil Kabeer Farha
- Department of Food Science & Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Hua-Bin Li
- Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Department of Nutrition, School of Public Health, Sun Yat-Sen University, Guangzhou, China
| | - Fan Zhu
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | - Xiao-Hong Wang
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Harold Corke
- Department of Food Science & Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
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7
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Gudeta DD, Lei MG, Lee CY. Contribution of hla Regulation by SaeR to Staphylococcus aureus USA300 Pathogenesis. Infect Immun 2019; 87:e00231-19. [PMID: 31209148 PMCID: PMC6704604 DOI: 10.1128/iai.00231-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/11/2019] [Indexed: 02/08/2023] Open
Abstract
The SaeRS two-component system in Staphylococcus aureus is critical for regulation of many virulence genes, including hla, which encodes alpha-toxin. However, the impact of regulation of alpha-toxin by Sae on S. aureus pathogenesis has not been directly addressed. Here, we mutated the SaeR-binding sequences in the hla regulatory region and determined the contribution of this mutation to hla expression and pathogenesis in strain USA300 JE2. Western blot analyses revealed drastic reduction of alpha-toxin levels in the culture supernatants of SaeR-binding mutant in contrast to the marked alpha-toxin production in the wild type. The SaeR-binding mutation had no significant effect on alpha-toxin regulation by Agr, MgrA, and CcpA. In animal studies, we found that the SaeR-binding mutation did not contribute to USA300 JE2 pathogenesis using a rat infective endocarditis model. However, in a rat skin and soft tissue infection model, the abscesses on rats infected with the mutant were significantly smaller than the abscesses on those infected with the wild type but similar to the abscesses on those infected with a saeR mutant. These studies indicated that there is a direct effect of hla regulation by SaeR on pathogenesis but that the effect depends on the animal model used.
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Affiliation(s)
- Dereje D Gudeta
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Mei G Lei
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Chia Y Lee
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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8
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Woo SG, Lee SM, Lee SY, Lim KH, Ha EJ, Kim SH, Eom YB. The effectiveness of anti-biofilm and anti-virulence properties of dihydrocelastrol and dihydrocelastryl diacetate in fighting against methicillin-resistant Staphylococcus aureus. Arch Microbiol 2017; 199:1151-1163. [DOI: 10.1007/s00203-017-1386-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 02/06/2017] [Accepted: 05/04/2017] [Indexed: 01/03/2023]
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9
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Hotterbeekx A, Kumar-Singh S, Goossens H, Malhotra-Kumar S. In vivo and In vitro Interactions between Pseudomonas aeruginosa and Staphylococcus spp. Front Cell Infect Microbiol 2017; 7:106. [PMID: 28421166 PMCID: PMC5376567 DOI: 10.3389/fcimb.2017.00106] [Citation(s) in RCA: 180] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 03/16/2017] [Indexed: 01/04/2023] Open
Abstract
The significance of polymicrobial infections is increasingly being recognized especially in a biofilm context wherein multiple bacterial species—including both potential pathogens and members of the commensal flora—communicate, cooperate, and compete with each other. Two important bacterial pathogens that have developed a complex network of evasion, counter-inhibition, and subjugation in their battle for space and nutrients are Pseudomonas aeruginosa and Staphylococcus aureus. Their strain- and environment-specific interactions, for instance in the cystic fibrosis lung or in wound infections, show severe competition that is generally linked to worse patient outcomes. For instance, the extracellular factors secreted by P. aeruginosa have been shown to subjugate S. aureus to persist as small colony variants (SCVs). On the other hand, data also exist where S. aureus inhibits biofilm formation by P. aeruginosa but also protects the pathogen by inhibiting its phagocytosis. Interestingly, such interspecies interactions differ between the planktonic and biofilm phenotype, with the extracellular matrix components of the latter likely being a key, and largely underexplored, influence. This review attempts to understand the complex relationship between P. aeruginosa and Staphylococcus spp., focusing on S. aureus, that not only is interesting from the bacterial evolution point of view, but also has important consequences for our understanding of the disease pathogenesis for better patient management.
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Affiliation(s)
- An Hotterbeekx
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of AntwerpWilrijk, Belgium
| | - Samir Kumar-Singh
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of AntwerpWilrijk, Belgium.,Molecular Pathology Group, Cell Biology and Histology, University of AntwerpWilrijk, Belgium
| | - Herman Goossens
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of AntwerpWilrijk, Belgium
| | - Surbhi Malhotra-Kumar
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of AntwerpWilrijk, Belgium
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Jomehpour N, Eslami G, Khalili MB. The Effect of Ferula assa-foetida L and Carum copticum Hydroalcoholic Extract on the Expression Levels of Staphylococcus aureus Genes Involved in Quorum Sensing. Jundishapur J Microbiol 2016; 9:e33879. [PMID: 27942357 PMCID: PMC5136442 DOI: 10.5812/jjm.33879] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 08/16/2016] [Accepted: 08/29/2016] [Indexed: 12/26/2022] Open
Abstract
Background Quorum sensing is a microbial cell-to-cell communication process. Quorum sensing bacteria produce and release extracellular messenger molecules called autoinducers. Gram-positive and Gram-negative, homoserine lactones, and oligopeptides are autoinducers used to communicate and regulate gene expression. Objectives The goal of this study was to assess the impact of subinhibitory concentrations of Ferula assa-foetida l oleo-gum resin and Carum copticum fruit on the expression of tst and hld genes of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains. Methods This analytical study was performed using standard strains of MRSA (ATCC 33591) and MSSA (ATCC 29213). Suspensions of MRSA and MSSA bacteria were incubated at 37°C for 7 and 16 hours in the presence of ethanol extracts from F. assa-foetida and C. copticum. The expression of the hld and tst genes was then assessed using the real-time PCR protocol and SYBR Green Master Mix. The data analysis was carried out using the 2-ΔΔCT method. Results The hld gene expression (RNAIII) of MRSA after 7 and 16 hours of exposure to the sMIC of the F. assa-foetida extract showed a fold change of -1 and 0.08, respectively, in comparison with controls. After 7 and 16 hours of exposure to the sMIC of the C. copticum extract, the fold change was -0.23 and -0.27, respectively. After exposure to the sMIC of the C. copticum extract for 16 hours, the fold change in the expression of the tst (TSST-1) MSSA gene was 0.37 lower than that of the control sample. Conclusions The results indicate that sMICs of ethanol extracts from F. assa-foetida and C. copticum can be used to control the expression of virulence genes in pathogenic bacteria, such as MRSA and MSSA.
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Affiliation(s)
- Najmeh Jomehpour
- Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran
| | - Gilda Eslami
- Research Center for Food Hygiene and Safety, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran
- Department of Parasitology and Mycology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran
- Corresponding author: Gilda Eslami, Department of Parasitology and Mycology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran. Tel/Fax: +98-3538203411, E-mail:
| | - Mohammad Bagher Khalili
- Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran
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11
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Mauro T, Rouillon A, Felden B. Insights into the regulation of small RNA expression: SarA represses the expression of two sRNAs in Staphylococcus aureus. Nucleic Acids Res 2016; 44:10186-10200. [PMID: 27596601 PMCID: PMC5137438 DOI: 10.1093/nar/gkw777] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 08/09/2016] [Accepted: 08/24/2016] [Indexed: 11/14/2022] Open
Abstract
The opportunistic pathogen Staphylococcus aureus expresses transcription factors (TFs) and regulatory small RNAs (sRNAs) which are essential for bacterial adaptation and infectivity. Until recently, the study of S. aureus sRNA gene expression regulation was under investigated, but it is now an expanding field. Here we address the regulation of Srn_3610_SprC sRNA, an attenuator of S. aureus virulence. We demonstrate that SarA TF represses srn_3610_sprC transcription. DNase I footprinting and deletion analyses show that the SarA binding site on srn_3610_sprC belongs to an essential 22 bp DNA region. Comparative analysis also revealed another possible site, this time in the srn_9340 promoter. SarA specifically binds these two sRNA promoters with high affinity in vitro and also represses their transcription in vivo. Chromatin immunoprecipitation (ChIP) assays confirmed SarA attachment to both promoters. ChIP and electrophoretic mobility shift assays targeting σA RNA polymerase subunit or using bacterial RNA polymerase holoenzyme suggested that SarA and the σA bind srn_3610_sprC and srn_9340 promoters in a mutually exclusive way. Beyond the mechanistic study of SarA repression of these two sRNAs, this work also suggests that some S. aureus sRNAs belong to the same regulon and act jointly in responding to environmental changes.
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Affiliation(s)
- Tony Mauro
- Inserm U835, Biochimie Pharmaceutique, University of Rennes 1, 35000 Rennes, France
| | - Astrid Rouillon
- Inserm U835, Biochimie Pharmaceutique, University of Rennes 1, 35000 Rennes, France
| | - Brice Felden
- Inserm U835, Biochimie Pharmaceutique, University of Rennes 1, 35000 Rennes, France
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12
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RpiRc Is a Pleiotropic Effector of Virulence Determinant Synthesis and Attenuates Pathogenicity in Staphylococcus aureus. Infect Immun 2016; 84:2031-2041. [PMID: 27113358 DOI: 10.1128/iai.00285-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 04/17/2016] [Indexed: 12/16/2022] Open
Abstract
In Staphylococcus aureus, metabolism is intimately linked with virulence determinant biosynthesis, and several metabolite-responsive regulators have been reported to mediate this linkage. S. aureus possesses at least three members of the RpiR family of transcriptional regulators. Of the three RpiR homologs, RpiRc is a potential regulator of the pentose phosphate pathway, which also regulates RNAIII levels. RNAIII is the regulatory RNA of the agr quorum-sensing system that controls virulence determinant synthesis. The effect of RpiRc on RNAIII likely involves other regulators, as the regulators that bind the RNAIII promoter have been intensely studied. To determine which regulators might bridge the gap between RpiRc and RNAIII, sarA, sigB, mgrA, and acnA mutations were introduced into an rpiRc mutant background, and the effects on RNAIII were determined. Additionally, phenotypic and genotypic differences were examined in the single and double mutant strains, and the virulence of select strains was examined using two different murine infection models. The data suggest that RpiRc affects RNAIII transcription and the synthesis of virulence determinants in concert with σ(B), SarA, and the bacterial metabolic status to negatively affect virulence.
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13
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Andrey DO, Jousselin A, Villanueva M, Renzoni A, Monod A, Barras C, Rodriguez N, Kelley WL. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus. PLoS One 2015; 10:e0135579. [PMID: 26275216 PMCID: PMC4537247 DOI: 10.1371/journal.pone.0135579] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 07/24/2015] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression.
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Affiliation(s)
- Diego O. Andrey
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland
| | - Ambre Jousselin
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
| | - Maite Villanueva
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
| | - Adriana Renzoni
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland
| | - Antoinette Monod
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland
| | - Christine Barras
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland
| | - Natalia Rodriguez
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
| | - William L. Kelley
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
- * E-mail:
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14
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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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15
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Contribution of teg49 small RNA in the 5' upstream transcriptional region of sarA to virulence in Staphylococcus aureus. Infect Immun 2014; 82:4369-79. [PMID: 25092913 DOI: 10.1128/iai.02002-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
High-throughput RNA sequencing technology has found the 5' untranslated region of sarA to contain two putative small RNAs (sRNAs), designated teg49 and teg48. Northern blot analysis disclosed that teg49 and teg48 were detectable within the P3-P1 and P1 sarA promoter regions, respectively. Focusing on teg49, we found that this sRNA, consisting of 196 nucleotides, is transcribed in the same direction as the sarA P3 transcript. The expression of both P3 and teg49 transcripts is dependent on sigB and cshA, which encodes a DEAD box RNA helicase. Within the sRNA teg49, there are two putative hairpin-loop structures, HP1 and HP2. Transversion mutation of the HP1 loop produced a smaller amount of sarA P3 and P2 transcripts and SarA protein than the corresponding HP1 stem and the HP2 stem and loop mutations, leading to lower RNAII transcription and derepression of aur transcription. The HP1 loop mutant also exhibited less biofilm formation than the parental and complemented strains. Complementation with shuttle plasmid pEPSA5 carrying teg49 was able to reestablish sarA P3 and P2 transcription and augment RNAII expression in the HP1 loop mutant. We thus conclude that teg49, embedded within the extended promoter regions of sarA, is modulated by sigB and cshA and plays an important trans-acting role in modulating the transcription and ensuing expression of sarA.
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16
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Lee K, Lee JH, Kim SI, Cho MH, Lee J. Anti-biofilm, anti-hemolysis, and anti-virulence activities of black pepper, cananga, myrrh oils, and nerolidol against Staphylococcus aureus. Appl Microbiol Biotechnol 2014; 98:9447-57. [PMID: 25027570 DOI: 10.1007/s00253-014-5903-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 06/11/2014] [Accepted: 06/16/2014] [Indexed: 01/30/2023]
Abstract
The long-term usage of antibiotics has resulted in the evolution of multidrug-resistant bacteria. Unlike antibiotics, anti-virulence approaches target bacterial virulence without affecting cell viability, which may be less prone to develop drug resistance. Staphylococcus aureus is a major human pathogen that produces diverse virulence factors, such as α-toxin, which is hemolytic. Also, biofilm formation of S. aureus is one of the mechanisms of its drug resistance. In this study, anti-biofilm screening of 83 essential oils showed that black pepper, cananga, and myrrh oils and their common constituent cis-nerolidol at 0.01 % markedly inhibited S. aureus biofilm formation. Furthermore, the three essential oils and cis-nerolidol at below 0.005 % almost abolished the hemolytic activity of S. aureus. Transcriptional analyses showed that black pepper oil down-regulated the expressions of the α-toxin gene (hla), the nuclease genes, and the regulatory genes. In addition, black pepper, cananga, and myrrh oils and cis-nerolidol attenuated S. aureus virulence in the nematode Caenorhabditis elegans. This study is one of the most extensive on anti-virulence screening using diverse essential oils and provides comprehensive data on the subject. This finding implies other beneficial effects of essential oils and suggests that black pepper, cananga, and myrrh oils have potential use as anti-virulence strategies against persistent S. aureus infections.
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Affiliation(s)
- Kayeon Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, 712-749, Republic of Korea
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17
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Beenken KE, Mrak LN, Zielinska AK, Atwood DN, Loughran AJ, Griffin LM, Matthews KA, Anthony AM, Spencer HJ, Skinner RA, Post GR, Lee CY, Smeltzer MS. Impact of the functional status of saeRS on in vivo phenotypes of Staphylococcus aureus sarA mutants. Mol Microbiol 2014; 92:1299-312. [PMID: 24779437 DOI: 10.1111/mmi.12629] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2014] [Indexed: 12/24/2022]
Abstract
We investigated the in vivo relevance of the impact of sarA and saeRS on protease production using derivatives of the USA300 strain LAC. The results confirmed that mutation of saeRS or sarA reduces virulence in a bacteremia model to a comparable degree. However, while eliminating protease production restored virulence in the sarA mutant, it had little impact in the saeRS mutant. Additionally, constitutive activation of saeRS (saeRS(C)) enhanced the virulence of LAC and largely restored virulence in the isogenic sarA mutant. Based on these results, together with our analysis of the representative virulence factors alpha toxin, protein A (Spa), and extracellular nucleases, we propose a model in which the attenuation of saeRS mutants is defined primarily by decreased production of such factors, while constitutive activation of saeRS increases virulence, and reverses the attenuation of sarA mutants, because it results in both increased production and decreased protease-mediated degradation of these same factors. This regulatory balance was also apparent in a murine model of catheter-associated infection, with the results suggesting that the impact of saeRS on nuclease production plays an important role during the early stages of these infections that is partially offset by increased protease production in sarA mutants.
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Affiliation(s)
- Karen E Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
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18
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Kunzmann MH, Bach NC, Bauer B, Sieber SA. α-Methylene-γ-butyrolactones attenuate Staphylococcus aureus virulence by inhibition of transcriptional regulation. Chem Sci 2014. [DOI: 10.1039/c3sc52228h] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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19
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Abstract
Staphylococcus aureus is a leading pathogen for animals and humans, not only being one of the most frequently isolated bacteria in hospital-associated infections but also causing diseases in the community. To coordinate the expression of its numerous virulence genes for growth and survival, S. aureus uses various signalling pathways that include two-component regulatory systems, transcription factors, and also around 250 regulatory RNAs. Biological roles have only been determined for a handful of these sRNAs, including cis, trans, and cis-trans acting RNAs, some internally encoding small, functional peptides and others possessing dual or multiple functions. Here we put forward an inventory of these fascinating sRNAs; the proteins involved in their activities; and those involved in stress response, metabolisms, and virulence.
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Affiliation(s)
- Julien Guillet
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
| | - Marc Hallier
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
| | - Brice Felden
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
- * E-mail:
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20
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Stieber B, Monecke S, Müller E, Baier V, Coombs GW, Ehricht R. Development and usage of protein microarrays for the quantitative measurement of Panton-Valentine leukocidin. Mol Cell Probes 2013; 28:123-32. [PMID: 24308917 DOI: 10.1016/j.mcp.2013.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/21/2013] [Accepted: 11/22/2013] [Indexed: 01/31/2023]
Abstract
Staphylococcus aureus is a human pathogen that can harbour several genes encoding exotoxins including leukocidins. A clinically most relevant factor is Panton-Valentine leukocidin (PVL) because of its association with chronic, recurrent or severe skin and soft tissue infections. In this study an antibody array was designed and used to obtain an overview about the in vitro PVL expression levels of 266 clinical isolates of MRSA as well as of MSSA belonging to a wide variety of clonal complexes. For that purpose, a novel precipitation based method was used. Unknown PVL concentrations were determined by mapping the signal intensities for spotted monoclonal antibodies to calibration curves that resulted from experiments with known concentrations of recombinant LukF-PV. In most cases, isolates belonging to one clonal complex (CC) showed similar PVL expressions. However, there were also CCs with widely varying PVL concentrations. First analyses, based on in vitro PVL measurements, showed low PVL concentrations in isolates from severe and fatal conditions that are not associated with PVL, such as sepsis, while isolates from skin and soft tissue infections yielded higher concentrations. Agr-group I and IV isolates generally produced more PVL than isolates from agr-groups II and III. The few isolates harbouring the gene encoding toxic shock syndrome toxin (tst1) were particularly low level PVL producers. However, these issues warrant further studies. The method described herein allows rapid quantification of expressed proteins such as PVL in collections of clinical isolates in order to correlate with clinical or genotypic data with a potential for further parallelisation.
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Affiliation(s)
- Bettina Stieber
- Alere Technologies GmbH, Jena, Germany; Institute for Medical Microbiology and Hygiene, Technical University of Dresden, Dresden, Germany.
| | - Stefan Monecke
- Alere Technologies GmbH, Jena, Germany; Institute for Medical Microbiology and Hygiene, Technical University of Dresden, Dresden, Germany
| | | | | | - Geoffrey W Coombs
- Department of Microbiology and Infectious Diseases, PathWest Laboratory Medicine - WA, Royal Perth Hospital, Perth, Western Australia, Australia; Australian Collaborating Centre for Enterococcus and Staphylococcus Species (ACCESS), Typing and Research, School of Biomedical Sciences, Curtin University, Perth, Western Australia, Australia
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21
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Clp chaperones and proteases are central in stress survival, virulence and antibiotic resistance of Staphylococcus aureus. Int J Med Microbiol 2013; 304:142-9. [PMID: 24457183 DOI: 10.1016/j.ijmm.2013.11.009] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Intracellular proteolysis carried out by energy-dependent proteases is one of the most conserved biological processes. In all cells proteolysis maintains and shapes the cellular proteome by ridding the cell of damaged proteins and by regulating abundance of functional proteins such as regulatory proteins. The ATP-dependent ClpP protease is highly conserved among eubacteria and in the chloroplasts and mitochondria of eukaryotic cells. In the serious human pathogen, Staphylococcus aureus inactivation of clpP rendered the bacterium avirulent emphasizing the central role of proteolysis in virulence. The contribution of the Clp proteins to virulence is likely to occur at multiple levels. First of all, both Clp ATPases and the Clp protease are central players in stress responses required to cope with the adverse conditions met in the host. The ClpP protease has a dual role herein, as it both eliminates stress-damaged proteins as well as ensures the timely degradation of major stress regulators such as Spx, LexA and CtsR. Additionally, as we will summarize in this review, Clp proteases and Clp chaperones impact on such central processes as virulence gene expression, cell wall metabolism, survival in stationary phase, and cell division. These observations together with recent findings that Clp proteins contribute to adaptation to antibiotics highlights the importance of this interesting proteolytic machinery both for understanding pathogenicity of the organism and for treating staphylococcal infections.
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22
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Genetic variation in the Staphylococcus aureus 8325 strain lineage revealed by whole-genome sequencing. PLoS One 2013; 8:e77122. [PMID: 24098817 PMCID: PMC3786944 DOI: 10.1371/journal.pone.0077122] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 09/05/2013] [Indexed: 01/05/2023] Open
Abstract
Staphylococcus aureus strains of the 8325 lineage, especially 8325-4 and derivatives lacking prophage, have been used extensively for decades of research. We report herein the results of our deep sequence analysis of strain 8325-4. Assignment of sequence variants compared with the reference strain 8325 (NRS77/PS47) required correction of errors in the 8325 reference genome, and reassessment of variation previously attributed to chemical mutagenesis of the restriction-defective RN4220. Using an extensive strain pedigree analysis, we discovered that 8325-4 contains 16 single nucleotide polymorphisms (SNP) arising prior to the construction of RN4220. We identified 5 indels in 8325-4 compared with 8325. Three indels correspond to expected Φ11, 12, 13 excisions, one indel is explained by a sequence assembly artifact, and the final indel (Δ63bp) in the spa-sarS intergenic region is common to only a sub-lineage of 8325-4 strains including SH1000. This deletion was found to significantly decrease (75%) steady state sarS but not spa transcript levels in post-exponential phase. The sub-lineage 8325-4 was also found to harbor 4 additional SNPs. We also found large sequence variation between 8325, 8325-4 and RN4220 in a cluster of repetitive hypothetical proteins (SA0282 homologs) near the Ess secretion cluster. The overall 8325-4 SNP set results in 17 alterations within coding sequences. Remarkably, we discovered that all tested strains of the 8325-4 lineage lack phenol soluble modulin α3 (PSMα3), a virulence determinant implicated in neutrophil chemotaxis, biofilm architecture and surface spreading. Collectively, our results clarify and define the 8325-4 pedigree and reveal clear evidence that mutations existing throughout all branches of this lineage, including the widely used RN6390 and SH1000 strains, could conceivably impact virulence regulation.
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23
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Zielinska AK, Beenken KE, Mrak LN, Spencer HJ, Post GR, Skinner RA, Tackett AJ, Horswill AR, Smeltzer MS. sarA-mediated repression of protease production plays a key role in the pathogenesis of Staphylococcus aureus USA300 isolates. Mol Microbiol 2012; 86:1183-96. [PMID: 23075270 DOI: 10.1111/mmi.12048] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2012] [Indexed: 01/31/2023]
Abstract
Mutation of staphylococcal accessory regulator (sarA) results in increased production of extracellular proteases in Staphylococcus aureus, which has been correlated with decreased biofilm formation and decreased accumulation of extracellular toxins. We used murine models of implant-associated biofilm infection and S. aureus bacteraemia (SAB) to compare virulence of USA300 strain LAC, its isogenic sarA mutant, and derivatives of each of these strains with mutations in all 10 of the genes encoding recognized extracellular proteases. The sarA mutant was attenuated in both models, and this was reversed by eliminating production of extracellular proteases. To examine the mechanistic basis, we identified proteins impacted by sarA in a protease-dependent manner. We identified 253 proteins where accumulation was reduced in the sarA mutant compared with the parent strain, and was restored in the sarA/protease mutant. Additionally, in SAB, the LAC protease mutant exhibited a hypervirulent phenotype by comparison with the isogenic parent strain, demonstrating that sarA also positively regulates production of virulence factors, some of which are subject to protease-mediated degradation. We propose a model in which attenuation of sarA mutants is defined by their inability to produce critical factors and simultaneously repress production of extracellular proteases that would otherwise limit accumulation of virulence factors.
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Affiliation(s)
- Agnieszka K Zielinska
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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24
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Junecko JM, Zielinska AK, Mrak LN, Ryan DC, Graham JW, Smeltzer MS, Lee CY. Transcribing virulence in Staphylococcus aureus. World J Clin Infect Dis 2012; 2:63-76. [DOI: 10.5495/wjcid.v2.i4.63] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is an important human pathogen capable of causing a diverse range of infections. Once regarded as an opportunistic pathogen causing primarily nosocomial infections, recent years have seen the emergence of S. aureus strains capable of causing serious infection even in otherwise healthy human hosts. There has been much debate about whether this transition is a function of unique genotypic characteristics or differences in the expression of conserved virulence factors, but irrespective of this debate it is clear that the ability of S. aureus to cause infection in all of its diverse forms is heavily influenced by its ability to modulate gene expression in response to changing conditions within the human host. Indeed, the S. aureus genome encodes more than 100 transcriptional regulators that modulate the production of virulence factors either directly via interactions with cis elements associated with genes encoding virulence factors or indirectly through their complex interactions with each other. The goal of this review is to summarize recent work describing these regulators and their contribution to defining S. aureus as a human pathogen.
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25
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Arya R, Princy SA. Computational approach to design small molecule inhibitors and identify SarA as a potential therapeutic candidate. Med Chem Res 2012. [DOI: 10.1007/s00044-012-0185-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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26
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Cue D, Lei MG, Lee CY. Genetic regulation of the intercellular adhesion locus in staphylococci. Front Cell Infect Microbiol 2012; 2:38. [PMID: 23061050 PMCID: PMC3459252 DOI: 10.3389/fcimb.2012.00038] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 03/05/2012] [Indexed: 01/29/2023] Open
Abstract
The formation of biofilms by Staphylococcus aureus and Staphylococcus epidermidis is an important aspect of many staphylococcal infections, most notably endocarditis, osteomyelitis and infections associated with indwelling medical devices. The major constituents of staphylococcal biofilms are polysaccharides, such as poly N-acetyl glucosamine (PIA/PNAG), cell surface and secreted bacterial proteins, and extracellular DNA. The exact composition of biofilms often varies considerably between different strains of staphylococci and between different sites of infection by the same strain. PIA/PNAG is synthesized by the products of four genes, icaADBC, that are encoded in a single operon. A fifth gene, icaR, is a negative regulator of icaADBC. Expression of icaADBC is tightly regulated, but can often be induced in vitro by growing staphylococci in the presence of high salt, high glucose, or ethanol. Regulation of icaADBC is complex and numerous regulatory factors have been implicated in control of icaADBC. Many of these are well known global transcriptional regulatory factors like SarA and sigmaB, whereas other regulators, such as IcaR, seem to affect expression of relatively few genes. Here, we will summarize how various regulatory factors affect the production of PIA/PNAG in staphylococci.
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Affiliation(s)
- David Cue
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock AR, USA
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27
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Frees D, Andersen JH, Hemmingsen L, Koskenniemi K, Bæk KT, Muhammed MK, Gudeta DD, Nyman TA, Sukura A, Varmanen P, Savijoki K. New Insights into Staphylococcus aureus Stress Tolerance and Virulence Regulation from an Analysis of the Role of the ClpP Protease in the Strains Newman, COL, and SA564. J Proteome Res 2011; 11:95-108. [DOI: 10.1021/pr200956s] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dorte Frees
- Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Stigbøjlen 4 DK-1870, Frederiksberg C, Denmark
| | - Julie Hove Andersen
- Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Stigbøjlen 4 DK-1870, Frederiksberg C, Denmark
| | - Lene Hemmingsen
- Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Stigbøjlen 4 DK-1870, Frederiksberg C, Denmark
- Department of Veterinary Biosciences, University of Helsinki, Finland
| | | | - Kristoffer T. Bæk
- Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Stigbøjlen 4 DK-1870, Frederiksberg C, Denmark
| | - Musemma Kedir Muhammed
- Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Stigbøjlen 4 DK-1870, Frederiksberg C, Denmark
| | - Dereje Dadi Gudeta
- Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Stigbøjlen 4 DK-1870, Frederiksberg C, Denmark
| | - Tuula A. Nyman
- Institute of Biotechnology, University of Helsinki, Finland
| | - Antti Sukura
- Department of Veterinary Biosciences, University of Helsinki, Finland
| | - Pekka Varmanen
- Department of Food and Environmental Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Finland
| | - Kirsi Savijoki
- Institute of Biotechnology, University of Helsinki, Finland
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28
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Vanderpool CK, Balasubramanian D, Lloyd CR. Dual-function RNA regulators in bacteria. Biochimie 2011; 93:1943-9. [PMID: 21816203 DOI: 10.1016/j.biochi.2011.07.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 07/08/2011] [Indexed: 12/18/2022]
Abstract
The importance of small RNA (sRNA) regulators has been recognized across all domains of life. In bacteria, sRNAs typically control the expression of virulence and stress response genes via antisense base pairing with mRNA targets. Originally dubbed "non-coding RNAs," a number of bacterial antisense sRNAs have been found to encode functional proteins. Although very few of these dual-function sRNAs have been characterized, they have been found in both gram-negative and gram-positive organisms. Among the few known examples, the functions and mechanisms of regulation by dual-function sRNAs are variable. Some dual-function sRNAs depend on the RNA chaperone Hfq for base pairing-dependent regulation (riboregulation); this feature appears so far exclusive to gram-negative bacterial sRNAs. Other variations can be found in the spatial organization of the coding region with respect to the riboregulation determinants. How the functions of encoded proteins relate to riboregulation is for the most part not understood. However, in one case it appears that there is physiological redundancy between protein and riboregulation functions. This mini-review focuses on the two best-studied bacterial dual-function sRNAs: RNAIII from Staphylococcus aureus and SgrS from Escherichia coli and includes a discussion of what is known about the structure, function and physiological roles of these sRNAs as well as what questions remain outstanding.
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Affiliation(s)
- Carin K Vanderpool
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA.
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29
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Zielinska AK, Beenken KE, Joo HS, Mrak LN, Griffin LM, Luong TT, Lee CY, Otto M, Shaw LN, Smeltzer MS. Defining the strain-dependent impact of the Staphylococcal accessory regulator (sarA) on the alpha-toxin phenotype of Staphylococcus aureus. J Bacteriol 2011; 193:2948-58. [PMID: 21478342 PMCID: PMC3133183 DOI: 10.1128/jb.01517-10] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 04/04/2011] [Indexed: 12/16/2022] Open
Abstract
We demonstrate that mutation of the staphylococcal accessory regulator (sarA) limits the accumulation of alpha-toxin and phenol-soluble modulins (PSMs) in Staphylococcus aureus isolates of the USA300 clonal lineage. Degradation assays and experiments done with protease inhibitors suggested that this was due to the increased production of extracellular proteases rather than differences associated with the impact of sarA on transcription of the target gene (hla) or the accessory gene regulator (agr). This was confirmed by demonstrating that concomitant mutation of the gene encoding aureolysin (aur) reversed the alpha-toxin and PSM-deficient phenotypes of a USA300 sarA mutant. Mutation of sarA had little impact on the alpha-toxin or PSM phenotypes of the commonly studied strain Newman, which is known to have a mutation in saeS that results in constitutive activation of the saeRS regulatory system, and we also demonstrate that repair of this defect resulted in the increased production of extracellular proteases and reversed both the alpha-toxin and PSM-positive phenotypes of a Newman sarA mutant.
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Affiliation(s)
- Agnieszka K Zielinska
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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Liang X, Hall JW, Yang J, Yan M, Doll K, Bey R, Ji Y. Identification of single nucleotide polymorphisms associated with hyperproduction of alpha-toxin in Staphylococcus aureus. PLoS One 2011; 6:e18428. [PMID: 21494631 PMCID: PMC3072997 DOI: 10.1371/journal.pone.0018428] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 03/06/2011] [Indexed: 12/02/2022] Open
Abstract
The virulence factor α-toxin (hla) is needed by Staphylococcus aureus in order to cause infections in both animals and humans. Although the complicated regulation of hla expression has been well studied in human S. aureus isolates, the mechanisms of of hla regulation in bovine S. aureus isolates remain undefined. In this study, we found that many bovine S. aureus isolates, including the RF122 strain, generate dramatic amounts of α-toxin in vitro compared with human clinical S. aureus isolates, including MRSA WCUH29 and MRSA USA300. To elucidate potential regulatory mechanisms, we analyzed the hla promoter regions and identified predominant single nucleotide polymorphisms (SNPs) at positions −376, −483, and −484 from the start codon in α-toxin hyper-producing isolates. Using site-directed mutagenesis and hla promoter-gfp-luxABCDE dual reporter approaches, we demonstrated that the SNPs contribute to the differential control of hla expression among bovine and human S. aureus isolates. Using a DNA affinity assay, gel-shift assays and a null mutant, we identified and revealed that an hla positive regulator, SarZ, contributes to the involvement of the SNPs in mediating hla expression. In addition, we found that the bovine S. aureus isolate RF122 exhibits higher transcription levels of hla positive regulators, including agrA, saeR, arlR and sarZ, but a lower expression level of hla repressor rot compared to the human S. aureus isolate WCUH29. Our results indicate α-toxin hyperproduction in bovine S. aureus is a multifactorial process, influenced at both the genomic and transcriptional levels. Moreover, the identification of predominant SNPs in the hla promoter region may provide a novel method for genotyping the S. aureus isolates.
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Affiliation(s)
- Xudong Liang
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Jeffrey W. Hall
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Junshu Yang
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Meiying Yan
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Katherine Doll
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Russell Bey
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Yinduo Ji
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, United States of America
- * E-mail:
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Regulatory mechanism for exfoliative toxin production in Staphylococcus aureus. Infect Immun 2011; 79:1660-70. [PMID: 21282415 DOI: 10.1128/iai.00872-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The exfoliative toxin (ET) is a major virulence factor of Staphylococcus aureus that causes bullous impetigo and its disseminated form, staphylococcal scalded-skin syndrome (SSSS). ET selectively digests one of the intracellular adhesion molecules, desmoglein 1, of epidermal keratinocytes and causes blisters due to intraepidermal cell-cell dissociation. Most S. aureus strains that cause blistering disease produce either ETA or ETB. They are serologically distinct molecules, where ETA is encoded on a phage genome and ETB is enocded on a large plasmid. ETA-producing S. aureus strains are frequently isolated from impetigo patients, and ETB-producing S. aureus strains are isolated from SSSS. ET-induced blister formation can be reproduced with the neonatal mouse. To determine the regulatory mechanism of ET production, we investigated the role of the two-component systems and global regulators for eta or etb expression in vitro and in vivo with the mouse model. Western blot and transcription analyses using a series of mutants demonstrate ETA production was downregulated by sigB, sarS, and sarA, while ETB production was downregulated by sigB and sarA but not by sarS. Production of both toxins is upregulated by saeRS, arlRS, and agrCA. Furthermore, by the in vivo neonatal mouse model, sigB and sarS but not sarA negatively regulate the exfoliation activity of the ETA-producing strain, while sarA negatively regulates the ETB-producing strain. In both strains, saeRS, arlRS, and agrCA positively regulate the exfoliation activity in vivo. The data illustrate similar but distinct regulatory mechanisms for ETA and ETB production in S. aureus in vitro as well as in vivo.
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Transcriptional profiling of XdrA, a new regulator of spa transcription in Staphylococcus aureus. J Bacteriol 2010; 192:5151-64. [PMID: 20675497 DOI: 10.1128/jb.00491-10] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcription of spa, encoding the virulence factor protein A in Staphylococcus aureus, is tightly controlled by a complex regulatory network, ensuring its temporal expression over growth and at appropriate stages of the infection process. Transcriptomic profiling of XdrA, a DNA-binding protein that is conserved in all S. aureus genomes and shares similarity with the XRE family of helix-turn-helix, antitoxin-like proteins, revealed it to be a previously unidentified activator of spa transcription. To assess how XdrA fits into the complex web of spa regulation, a series of regulatory mutants were constructed; consisting of single, double, triple, and quadruple mutants lacking XdrA and/or the three key regulators previously shown to influence spa transcription directly (SarS, SarA, and RNAIII). A series of lacZ reporter gene fusions containing nested deletions of the spa promoter identified regions influenced by XdrA and the other three regulators. XdrA had almost as strong an activating effect on spa as SarS and acted on the same spa operator regions as SarS, or closely overlapping regions. All data from microarrays, Northern and Western blot analyses, and reporter gene fusion experiments indicated that XdrA is a major activator of spa expression that appears to act directly on the spa promoter and not through previously characterized regulators.
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Eugenol reduces the expression of virulence-related exoproteins in Staphylococcus aureus. Appl Environ Microbiol 2010; 76:5846-51. [PMID: 20639367 DOI: 10.1128/aem.00704-10] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Eugenol, an essential oil component in plants, has been demonstrated to possess activity against both gram-positive and gram-negative bacteria. This study examined the influence that subinhibitory concentrations of eugenol may have on the expression of the major exotoxins produced by Staphylococcus aureus. The results from a tumor necrosis factor (TNF) release assay and a hemolysin assay indicated that S. aureus cultured with graded subinhibitory concentrations of eugenol (16 to 128 microg/ml) dose dependently decreased the TNF-inducing and hemolytic activities of culture supernatants. Western blot analysis showed that eugenol significantly reduced the production of staphylococcal enterotoxin A (SEA), SEB, and toxic shock syndrome toxin 1 (the key exotoxins to induce TNF release), as well as the expression of alpha-hemolysin (the major hemolysin to cause hemolysis). In addition, this suppression was also evaluated at the transcriptional level via real-time reverse transcription (RT)-PCR analysis. The transcriptional analysis indicated that 128 microg/ml of eugenol remarkably repressed the transcription of the S. aureus sea, seb, tst, and hla genes. According to these results, eugenol has the potential to be rationally applied on food products as a novel food antimicrobial agent both to inhibit the growth of bacteria and to suppress the production of exotoxins by S. aureus.
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The cvfC operon of Staphylococcus aureus contributes to virulence via expression of the thyA gene. Microb Pathog 2010; 49:1-7. [DOI: 10.1016/j.micpath.2010.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 03/13/2010] [Accepted: 03/19/2010] [Indexed: 02/07/2023]
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Beenken KE, Mrak LN, Griffin LM, Zielinska AK, Shaw LN, Rice KC, Horswill AR, Bayles KW, Smeltzer MS. Epistatic relationships between sarA and agr in Staphylococcus aureus biofilm formation. PLoS One 2010; 5:e10790. [PMID: 20520723 PMCID: PMC2875390 DOI: 10.1371/journal.pone.0010790] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 04/30/2010] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The accessory gene regulator (agr) and staphylococcal accessory regulator (sarA) play opposing roles in Staphylococcus aureus biofilm formation. There is mounting evidence to suggest that these opposing roles are therapeutically relevant in that mutation of agr results in increased biofilm formation and decreased antibiotic susceptibility while mutation of sarA has the opposite effect. To the extent that induction of agr or inhibition of sarA could potentially be used to limit biofilm formation, this makes it important to understand the epistatic relationships between these two loci. METHODOLOGY/PRINCIPAL FINDINGS We generated isogenic sarA and agr mutants in clinical isolates of S. aureus and assessed the relative impact on biofilm formation. Mutation of agr resulted in an increased capacity to form a biofilm in the 8325-4 laboratory strain RN6390 but had little impact in clinical isolates S. aureus. In contrast, mutation of sarA resulted in a reduced capacity to form a biofilm in all clinical isolates irrespective of the functional status of agr. This suggests that the regulatory role of sarA in biofilm formation is independent of the interaction between sarA and agr and that sarA is epistatic to agr in this context. This was confirmed by demonstrating that restoration of sarA function restored the ability to form a biofilm even in the corresponding agr mutants. Mutation of sarA in clinical isolates also resulted in increased production of extracellular proteases and extracellular nucleases, both of which contributed to the biofilm-deficient phenotype of sarA mutants. However, studies comparing different strains with and without proteases inhibitors and/or mutation of the nuclease genes demonstrated that the agr-independent, sarA-mediated repression of extracellular proteases plays a primary role in this regard. CONCLUSIONS AND SIGNIFICANCE The results we report suggest that inhibitors of sarA-mediated regulation could be used to limit biofilm formation in S. aureus and that the efficacy of such inhibitors would not be limited by spontaneous mutation of agr in the human host.
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Affiliation(s)
- Karen E. Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Lara N. Mrak
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Linda M. Griffin
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Agnieszka K. Zielinska
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Lindsey N. Shaw
- Department of Biology, University of South Florida, Tampa, Florida, United States of America
| | - Kelly C. Rice
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, United States of America
| | - Alexander R. Horswill
- Department of Microbiology, University of Iowa, Iowa City, Iowa, United States of America
| | - Kenneth W. Bayles
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Mark S. Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- * E-mail:
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Xiang H, Qiu JZ, Wang DC, Jiang YS, Xia LJ, Deng XM. Influence of magnolol on the secretion of alpha-toxin by Staphylococcus aureus. Molecules 2010; 15:1679-89. [PMID: 20336007 PMCID: PMC6257330 DOI: 10.3390/molecules15031679] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 02/08/2010] [Accepted: 03/02/2010] [Indexed: 11/16/2022] Open
Abstract
In this study we investigated the antimicrobial activity of magnolol on Staphylococcus aureus. The minimal inhibitory concentrations of magnolol against 31 S. aureus strains ranged from 4–32 μg/mL. In addition, hemolysin assays, Western blotting, and real-time RT-PCR were performed to investigate the effect of magnolol on α-toxin secretion by both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). The results indicated that sub-inhibitory concentrations of magnolol dose-dependently inhibited the transcription of hla (the gene encoding α-toxin) in S. aureus, resulting in a reduction of α-toxin secretion and, thus, hemolytic activities.
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Affiliation(s)
- Hua Xiang
- Institute of Zoonoses, College of Animal Sciences and Veterinary Medicine, Jilin University, Changchun, Jilin 130062, China; E-Mails: (H.X.); (J.-Z.Q.)
| | - Jia-Zhang Qiu
- Institute of Zoonoses, College of Animal Sciences and Veterinary Medicine, Jilin University, Changchun, Jilin 130062, China; E-Mails: (H.X.); (J.-Z.Q.)
| | - Da-Cheng Wang
- Institute of Zoonoses, College of Animal Sciences and Veterinary Medicine, Jilin University, Changchun, Jilin 130062, China; E-Mails: (H.X.); (J.-Z.Q.)
| | - You-Shuai Jiang
- College of Life Science and Technology, Heilongjiang August First Agricultural University, Daqing, Heilongjiang 163319, China; E-Mail: (Y.-S.J.)
| | - Li-Jie Xia
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangshu 225009, China; E-Mail: (L.-J.X.)
| | - Xu-Ming Deng
- Institute of Zoonoses, College of Animal Sciences and Veterinary Medicine, Jilin University, Changchun, Jilin 130062, China; E-Mails: (H.X.); (J.-Z.Q.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +86 431 87836161; Fax: +86 431 87836160
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Qiu J, Jiang Y, Xia L, Xiang H, Feng H, Pu S, Huang N, Yu L, Deng X. Subinhibitory concentrations of licochalcone A decrease alpha-toxin production in both methicillin-sensitive and methicillin-resistantStaphylococcus aureusisolates. Lett Appl Microbiol 2010; 50:223-9. [DOI: 10.1111/j.1472-765x.2009.02783.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Fujimoto DF, Higginbotham RH, Sterba KM, Maleki SJ, Segall AM, Smeltzer MS, Hurlburt BK. Staphylococcus aureus SarA is a regulatory protein responsive to redox and pH that can support bacteriophage lambda integrase-mediated excision/recombination. Mol Microbiol 2009; 74:1445-58. [PMID: 19919677 DOI: 10.1111/j.1365-2958.2009.06942.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Staphylococcus aureus produces a wide array of virulence factors and causes a correspondingly diverse array of infections. Production of these virulence factors is under the control of a complex network of global regulatory elements, one of which is sarA. sarA encodes a DNA binding protein that is considered to function as a transcription factor capable of acting as either a repressor or an activator. Using competitive ELISA assays, we demonstrate that SarA is present at approximately 50 000 copies per cell, which is not characteristic of classical transcription factors. We also demonstrate that SarA is present at all stages of growth in vitro and is capable of binding DNA with high affinity but that its binding affinity and pattern of shifted complexes in electrophoretic mobility shift assays is responsive to the redox state. We also show that SarA binds to the bacteriophage lambda (lambda) attachment site, attL, producing SarA-DNA complexes similar to intasomes, which consist of bacteriophage lambda integrase, Escherichia coli integration host factor and attL DNA. In addition, SarA stimulates intramolecular excision recombination in the absence of lambda excisionase, a DNA binding accessory protein. Taken together, these data suggest that SarA may function as an architectural accessory protein.
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Affiliation(s)
- David F Fujimoto
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
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Franke GC, Böckenholt A, Sugai M, Rohde H, Aepfelbacher M. Epidemiology, variable genetic organization and regulation of the EDIN-B toxin in Staphylococcus aureus from bacteraemic patients. MICROBIOLOGY-SGM 2009; 156:860-872. [PMID: 19875439 DOI: 10.1099/mic.0.030304-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
EDIN-B (epidermal cell differentiation inhibitor-B; also termed C3Stau) is an exotoxin of Staphylococcus aureus which ADP-ribosylates and inactivates Rho GTP binding proteins. The EDIN-B gene (edin-B) and the gene for exfoliative toxin D (etd) make up the central part of a recently described pathogenicity island. Here we evaluated the prevalence and genetic organization of the edin-B/etd pathogenicity island in invasive S. aureus isolates, and characterized edin-B transcription and EDIN-B production using artificial constructs transduced in S. aureus strains RN6390 and Newman. We found that eight out of 121 (7 %) S. aureus blood culture isolates harbour edin-B, which is organized in three novel variants of the original edin-B/etd pathogenicity island. In the serum of patients infected with edin-B-positive S. aureus, significant titres of anti-EDIN-B antibodies could be detected. Regulation of edin-B transcription depended on the sarA but not on the agr regulatory system. Furthermore, retrieval of EDIN-B protein secreted by S. aureus RN6390 required the presence of alpha2-macroglobulin to inhibit the activity of extracellular proteases. These data suggest that the EDIN-B toxin is produced during human infection, is part of a highly variable pathogenicity island and can be controlled by the sarA gene regulon and secreted bacterial proteases.
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Affiliation(s)
- Gefion C Franke
- Institut für Medizinische Mikrobiologie, Virologie und Hygiene, University Medical Center Hamburg-Eppendorf, Martinistraße52, 20246 Hamburg, Germany
| | - Alexandra Böckenholt
- Institut für Medizinische Mikrobiologie, Virologie und Hygiene, University Medical Center Hamburg-Eppendorf, Martinistraße52, 20246 Hamburg, Germany
| | - Motoyuki Sugai
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
| | - Holger Rohde
- Institut für Medizinische Mikrobiologie, Virologie und Hygiene, University Medical Center Hamburg-Eppendorf, Martinistraße52, 20246 Hamburg, Germany
| | - Martin Aepfelbacher
- Institut für Medizinische Mikrobiologie, Virologie und Hygiene, University Medical Center Hamburg-Eppendorf, Martinistraße52, 20246 Hamburg, Germany
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Impact of sarA on daptomycin susceptibility of Staphylococcus aureus biofilms in vivo. Antimicrob Agents Chemother 2009; 53:4096-102. [PMID: 19651914 DOI: 10.1128/aac.00484-09] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We used a murine model of catheter-associated biofilm formation to determine whether the mutation of the staphylococcal accessory regulator (sarA) has an impact on the susceptibility of established Staphylococcus aureus biofilms to treatment with daptomycin in vivo. The experiments were done with two clinical isolates, one of which (UAMS-1) was obtained from the bone of a patient suffering from osteomyelitis, while the other (UAMS-1625) is an isolate of the USA300 clonal lineage of community-acquired methicillin (meticillin)-resistant S. aureus. UAMS-1625 had a reduced capacity to form a biofilm in vivo compared to that of UAMS-1 (P = 0.0015), but in both cases the mutation of sarA limited biofilm formation compared to that of the corresponding parent strain (P < or = 0.001). The mutation of sarA did not affect the daptomycin MIC for either strain, but it did result in increased susceptibility in vivo in the context of an established biofilm. Specifically, daptomycin treatment resulted in the clearance of detectable bacteria from <10% of the catheters colonized with the parent strains, while treatment with an equivalent daptomycin concentration resulted in the clearance of 46.4% of the catheters colonized with the UAMS-1 sarA mutant and 69.1% of the catheters colonized with the UAMS-1625 sarA mutant. In the absence of daptomycin treatment, mice with catheters colonized with the UAMS-1625 parent strain also developed skin lesions in the region adjacent to the implanted catheter. No such lesions were observed in any other experimental group, including untreated mice containing catheters colonized with the UAMS-1625 sarA mutant.
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Nagarajan V, Smeltzer MS, Elasri MO. Genome-scale transcriptional profiling in Staphylococcus aureus : bringing order out of chaos. FEMS Microbiol Lett 2009; 295:204-10. [PMID: 19459979 PMCID: PMC2753426 DOI: 10.1111/j.1574-6968.2009.01595.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We used the Staphylococcus aureus microarray meta-database (SAMMD) to compare the transcriptional profiles defined by different experiments targeting the same phenomenon in S. aureus. We specifically examined differences associated with the accessory gene regulator (agr), the staphylococcal accessory regulator (sarA), and growth within a biofilm. We found that in all three cases, there was a striking lack of overlap between the transcriptional profiles. For instance, while all experiments focusing on biofilm formation identified hundreds of differentially expressed genes, only one of these was common to all transcriptomes. Several factors could potentially contribute to this variability including the use of different biofilm models, different growth media, different microarray platforms, and, perhaps most importantly, different strains of S. aureus. The last appeared to be particularly important in the case of the agr and sarA transcriptomes. While these results emphasize the need to introduce some degree of standardization into genome-scale, microarray-based transcriptional profiling experiments, they also demonstrate the need to consider multiple strains of S. aureus in order to avoid any strain-specific bias in the interpretation of results. Our comparisons also illustrate how identification of strain-dependent differences using SAMMD can lead to the development of specific hypotheses that can then be experimentally addressed. Based on this, we have added new features to SAMMD that allow for direct comparisons between transcriptional profiling experiments.
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Affiliation(s)
- Vijayaraj Nagarajan
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Mark S. Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Mohamed O. Elasri
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406, USA
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Kenny JG, Ward D, Josefsson E, Jonsson IM, Hinds J, Rees HH, Lindsay JA, Tarkowski A, Horsburgh MJ. The Staphylococcus aureus response to unsaturated long chain free fatty acids: survival mechanisms and virulence implications. PLoS One 2009; 4:e4344. [PMID: 19183815 PMCID: PMC2629846 DOI: 10.1371/journal.pone.0004344] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Accepted: 12/18/2008] [Indexed: 12/13/2022] Open
Abstract
Staphylococcus aureus is an important human commensal and opportunistic pathogen responsible for a wide range of infections. Long chain unsaturated free fatty acids represent a barrier to colonisation and infection by S. aureus and act as an antimicrobial component of the innate immune system where they are found on epithelial surfaces and in abscesses. Despite many contradictory reports, the precise anti-staphylococcal mode of action of free fatty acids remains undetermined. In this study, transcriptional (microarrays and qRT-PCR) and translational (proteomics) analyses were applied to ascertain the response of S. aureus to a range of free fatty acids. An increase in expression of the σB and CtsR stress response regulons was observed. This included increased expression of genes associated with staphyloxanthin synthesis, which has been linked to membrane stabilisation. Similarly, up-regulation of genes involved in capsule formation was recorded as were significant changes in the expression of genes associated with peptidoglycan synthesis and regulation. Overall, alterations were recorded predominantly in pathways involved in cellular energetics. In addition, sensitivity to linoleic acid of a range of defined (sigB, arcA, sasF, sarA, agr, crtM) and transposon-derived mutants (vraE, SAR2632) was determined. Taken together, these data indicate a common mode of action for long chain unsaturated fatty acids that involves disruption of the cell membrane, leading to interference with energy production within the bacterial cell. Contrary to data reported for other strains, the clinically important EMRSA-16 strain MRSA252 used in this study showed an increase in expression of the important virulence regulator RNAIII following all of the treatment conditions tested. An adaptive response by S. aureus of reducing cell surface hydrophobicity was also observed. Two fatty acid sensitive mutants created during this study were also shown to diplay altered pathogenesis as assessed by a murine arthritis model. Differences in the prevalence and clinical importance of S. aureus strains might partly be explained by their responses to antimicrobial fatty acids.
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Affiliation(s)
- John G. Kenny
- School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Deborah Ward
- School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Elisabet Josefsson
- Department of Rheumatology and Inflammation Research, University of Gothenburg, Göteborg, Sweden
| | - Ing-Marie Jonsson
- Department of Rheumatology and Inflammation Research, University of Gothenburg, Göteborg, Sweden
| | - Jason Hinds
- Division of Cellular & Molecular Medicine, St George's, University of London, London, United Kingdom
| | - Huw H. Rees
- School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Jodi A. Lindsay
- Division of Cellular & Molecular Medicine, St George's, University of London, London, United Kingdom
| | - Andrej Tarkowski
- Department of Rheumatology and Inflammation Research, University of Gothenburg, Göteborg, Sweden
| | - Malcolm J. Horsburgh
- School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
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SarZ promotes the expression of virulence factors and represses biofilm formation by modulating SarA and agr in Staphylococcus aureus. Infect Immun 2008; 77:419-28. [PMID: 18955469 DOI: 10.1128/iai.00859-08] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Staphylococcus aureus is a remarkably adaptable organism capable of multiple modes of growth in the human host, as a part of the normal flora, as a pathogen, or as a biofilm. Many of the regulatory pathways governing these modes of growth are centered on the activities of two regulatory molecules, the DNA binding protein SarA and the regulatory RNAIII effector molecule of the agr system. Here, we describe the modulation of these regulators and their downstream target genes by SarZ, a member of the SarA/MarR family of transcriptional regulators. Transcriptional and phenotypic analyses of a sarZ mutant demonstrated that the decreased transcription of mgrA and the agr RNAIII molecule was accompanied by increased transcription of spa (protein A) and downregulation of hla (alpha-hemolysin) and sspA (V8 protease) transcripts when compared to its isogenic parent. The decrease in protease activity was also associated with an increase in SarA expression. Consistent with an increase in SarA levels, the sarZ mutant displayed an enhanced ability to form biofilms. Together, our results indicate that SarZ may be an important regulator governing the dissemination phase of S. aureus infections, as it promotes toxin expression while repressing factors required for biofilm formation.
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Gustafsson E, Oscarsson J. Maximal transcription of aur (aureolysin) and sspA (serine protease) in Staphylococcus aureus requires staphylococcal accessory regulator R (sarR) activity. FEMS Microbiol Lett 2008; 284:158-64. [PMID: 18576947 DOI: 10.1111/j.1574-6968.2008.01198.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Previous studies have shown that expression of aur (metalloprotease; aureolysin) and sspA (V8 protease; serine protease) in Staphylococcus aureus strain 8325-4 is maximal in the postexponential phase of growth, when the agr (RNAIII) system is activated. Transcription of aur and sspA is mainly regulated through repression by sarA and rot, and RNAIII stimulates protease production by inhibiting translation of rot mRNA. As SarR is a repressor of sarA, inactivation of sarR would result in downregulation of aur and sspA transcription. This was confirmed by mRNA analysis using quantitative real-time PCR. However, we found that sarR acted as a direct stimulator, i.e. its positive effect on aur and sspA transcription did not require sarA (or rot) per se. In addition, aur and sspA were dependent on sarR for maximal transcription. This stimulating role of sarR was not restricted to the rsbU-deficient laboratory strain 8325-4 but was also demonstrated in S. aureus strain SH1000 (rsbU-complemented derivative of 8325-4) and in one clinical isolate.
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Affiliation(s)
- Erik Gustafsson
- School of Life Sciences, University of Skövde, Skövde, Sweden.
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Cheung AL, Nishina KA, Trotonda MP, Tamber S. The SarA protein family of Staphylococcus aureus. Int J Biochem Cell Biol 2007; 40:355-61. [PMID: 18083623 PMCID: PMC2274939 DOI: 10.1016/j.biocel.2007.10.032] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 10/20/2007] [Accepted: 10/29/2007] [Indexed: 12/20/2022]
Abstract
Staphylococcus aureus is widely appreciated as an opportunistic pathogen, primarily in hospital-related infections. However, recent reports indicate that S. aureus infections can now occur in other wise healthy individuals in the community setting. The success of this organism can be attributed to the large array of regulatory proteins, including the SarA protein family, used to respond to changing microenvironments. Sequence alignment and structural data reveal that the SarA protein family can be divided into three subfamilies: (1) single domain proteins; (2) double domain proteins; (3) MarR homologs. Structural studies have also demonstrated that SarA, SarR, SarS, MgrA and thus possibly all members of this protein family are winged helix proteins with minor variations. Mutagenesis studies of SarA disclose that the winged helix motifs are important for DNA binding and function. Recent progress concerning the functions and plausible mechanisms of regulation of SarA and its homologs are discussed.
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Affiliation(s)
- Ambrose L Cheung
- Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, NH 03755, USA.
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Kuroda H, Kuroda M, Cui L, Hiramatsu K. Subinhibitory concentrations of β-lactam induce haemolytic activity inStaphylococcus aureusthrough the SaeRS two-component system. FEMS Microbiol Lett 2007; 268:98-105. [PMID: 17263851 DOI: 10.1111/j.1574-6968.2006.00568.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SaeRS is a two-component system that has been characterized as a positive regulatory system for the expression of several virulence factors, including coagulase, alpha-, beta- and gamma-haemolysins, nuclease, and fibronectin-binding proteins in Staphylococcus aureus. Previously, the SaeRS system was found to be induced at the transcriptional level by beta-lactam. Here, we found that subinhibitory concentrations of beta-lactam induce haemolytic activity in the S. aureus N315 strain but not in the saeRS null mutant KSA. Comparison of the transcriptional profile of the N315 and KSA strains by microarray analysis reveals that the SaeRS system modulates the regulation of coagulase (coa), alpha-, beta- and gamma-haemolysins (hla, hlb and hlg), nuclease (SA0746), fibrinogen-binding proteins (emp, efb, SA1000 and SA1004), fibronectin-binding protein B (fnbB), and 13 other genes. Further, the use of cefoxitin as a signal inducer reveals that the SaeRS system appears to modulate 22 additional genes as a secondary regulon, including the staphylococcal accessory regulators SarA and SarT and the Clp protease ATPase subunits ClpB and ClpL. These observations suggest that beta-lactam is able to induce the SaeRS system, which acts as a crucial signal transduction system for S. aureus pathogenicity rather than antimicrobial resistance.
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Affiliation(s)
- Hiroko Kuroda
- Department of Bacteriology, Juntendo University, Hongo, Tokyo, Japan
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