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Jacob KM, Hernández-Villamizar S, Hammer ND, Reguera G. Mucin-induced surface dispersal of Staphylococcus aureus and Staphylococcus epidermidis via quorum-sensing dependent and independent mechanisms. mBio 2024:e0156224. [PMID: 38953351 DOI: 10.1128/mbio.01562-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Accepted: 06/04/2024] [Indexed: 07/04/2024] Open
Abstract
Nasopharyngeal carriage of staphylococci spreads potentially pathogenic strains into (peri)oral regions and increases the chance of cross-infections. Some laboratory strains can also move rapidly on hydrated agar surfaces, but the biological relevance of these observations is not clear. Using soft-agar [0.3% (wt/vol)] plate assays, we demonstrate the rapid surface dispersal of (peri)oral isolates of Staphylococcus aureus and Staphylococcus epidermidis and closely related laboratory strains in the presence of mucin glycoproteins. Mucin-induced dispersal was a stepwise process initiated by the passive spreading of the growing colonies followed by their rapid branching (dendrites) from the colony edge. Although most spreading strains used mucin as a growth substrate, dispersal was primarily dependent on the lubricating and hydrating properties of the mucins. Using S. aureus JE2 as a genetically tractable representative, we demonstrate that mucin-induced dendritic dispersal, but not colony spreading, is facilitated by the secretion of surfactant-active phenol-soluble modulins (PSMs) in a process regulated by the agr quorum-sensing system. Furthermore, the dendritic dispersal of S. aureus JE2 colonies was further stimulated in the presence of surfactant-active supernatants recovered from the most robust (peri)oral spreaders of S. aureus and S. epidermidis. These findings suggest complementary roles for lubricating mucins and staphylococcal PSMs in the active dispersal of potentially pathogenic strains from perioral to respiratory mucosae, where gel-forming, hydrating mucins abound. They also highlight the impact that interspecies interactions have on the co-dispersal of S. aureus with other perioral bacteria, heightening the risk of polymicrobial infections and the severity of the clinical outcomes. IMPORTANCE Despite lacking classical motility machinery, nasopharyngeal staphylococci spread rapidly in (peri)oral and respiratory mucosa and cause cross-infections. We describe laboratory conditions for the reproducible study of staphylococcal dispersal on mucosa-like surfaces and the identification of two dispersal stages (colony spreading and dendritic expansion) stimulated by mucin glycoproteins. The mucin type mattered as dispersal required the surfactant activity and hydration provided by some mucin glycoproteins. While colony spreading was a passive mode of dispersal lubricated by the mucins, the more rapid and invasive form of dendritic expansion of Staphylococcus aureus and Staphylococcus epidermidis required additional lubrication by surfactant-active peptides (phenol-soluble modulins) secreted at high cell densities through quorum sensing. These results highlight a hitherto unknown role for gel-forming mucins in the dispersal of staphylococcal strains associated with cross-infections and point at perioral regions as overlooked sources of carriage and infection by staphylococci.
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Affiliation(s)
- Kristin M Jacob
- Department of Microbiology, Genetics and Immunology, Michigan State University, East Lansing, Michigan, USA
| | | | - Neal D Hammer
- Department of Microbiology, Genetics and Immunology, Michigan State University, East Lansing, Michigan, USA
| | - Gemma Reguera
- Department of Microbiology, Genetics and Immunology, Michigan State University, East Lansing, Michigan, USA
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2
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Gallo RL, Horswill AR. Staphylococcus aureus: The Bug Behind the Itch in Atopic Dermatitis. J Invest Dermatol 2024; 144:950-953. [PMID: 38430083 DOI: 10.1016/j.jid.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 12/29/2023] [Accepted: 01/02/2024] [Indexed: 03/03/2024]
Abstract
Pruritus or itch is a defining symptom of atopic dermatitis (AD). The origins of itch are complex, and it is considered both a defense mechanism and a cause of disease that leads to inflammation and psychological stress. Considerable progress has been made in understanding the processes that trigger itch, particularly the pruritoceptive origins that are generated in the skin. This perspective review discusses the implications of a recent observation that the V8 protease expressed by Staphylococcus aureus can directly trigger sensory neurons in the skin through activation of protease-activated receptor 1. This may be a key to understanding why itch is so common in AD because S. aureus commonly overgrows in this disease owing to deficient antimicrobial defense from both the epidermis and the cutaneous microbiome. Increased understanding of the role of microbes in AD provides increased opportunities for safely improving the treatment of this disorder.
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Affiliation(s)
- Richard L Gallo
- Department of Dermatology, University of California San Diego, La Jolla, California, USA.
| | - Alexander R Horswill
- Department of Immunology & Microbiology, School of Medicine, University of Colorado, Aurora, Colorado, USA
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3
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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: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [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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4
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Pivard M, Bastien S, Macavei I, Mouton N, Rasigade JP, Couzon F, Youenou B, Tristan A, Carrière R, Moreau K, Lemoine J, Vandenesch F. Targeted proteomics links virulence factor expression with clinical severity in staphylococcal pneumonia. Front Cell Infect Microbiol 2023; 13:1162617. [PMID: 37077532 PMCID: PMC10106754 DOI: 10.3389/fcimb.2023.1162617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 03/20/2023] [Indexed: 04/05/2023] Open
Abstract
IntroductionThe bacterial pathogen Staphylococcus aureus harbors numerous virulence factors that impact infection severity. Beyond virulence gene presence or absence, the expression level of virulence proteins is known to vary across S. aureus lineages and isolates. However, the impact of expression level on severity is poorly understood due to the lack of high-throughput quantification methods of virulence proteins.MethodsWe present a targeted proteomic approach able to monitor 42 staphylococcal proteins in a single experiment. Using this approach, we compared the quantitative virulomes of 136 S. aureus isolates from a nationwide cohort of French patients with severe community-acquired staphylococcal pneumonia, all requiring intensive care. We used multivariable regression models adjusted for patient baseline health (Charlson comorbidity score) to identify the virulence factors whose in vitro expression level predicted pneumonia severity markers, namely leukopenia and hemoptysis, as well as patient survival.ResultsWe found that leukopenia was predicted by higher expression of HlgB, Nuc, and Tsst-1 and lower expression of BlaI and HlgC, while hemoptysis was predicted by higher expression of BlaZ and HlgB and lower expression of HlgC. Strikingly, mortality was independently predicted in a dose-dependent fashion by a single phage-encoded virulence factor, the Panton-Valentine leucocidin (PVL), both in logistic (OR 1.28; 95%CI[1.02;1.60]) and survival (HR 1.15; 95%CI[1.02;1.30]) regression models.DiscussionThese findings demonstrate that the in vitro expression level of virulence factors can be correlated with infection severity using targeted proteomics, a method that may be adapted to other bacterial pathogens.
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Affiliation(s)
- Mariane Pivard
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
| | - Sylvère Bastien
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
| | - Iulia Macavei
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - Nicolas Mouton
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - Jean-Philippe Rasigade
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France
| | - Florence Couzon
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
| | - Benjamin Youenou
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France
| | - Anne Tristan
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France
| | - Romain Carrière
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - Karen Moreau
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
| | - Jérôme Lemoine
- Institut des Sciences Analytiques, Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR 5280, Villeurbanne, France
| | - François Vandenesch
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique (CNRS), UMR5308, École Normale Supérieure (ENS) de Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Institut des agents infectieux, Hospices Civils de Lyon, Lyon, France
- *Correspondence: François Vandenesch,
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5
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Viering B, Cunningham T, King A, Blackledge MS, Miller HB. Brominated Carbazole with Antibiotic Adjuvant Activity Displays Pleiotropic Effects in MRSA's Transcriptome. ACS Chem Biol 2022; 17:1239-1248. [PMID: 35467845 DOI: 10.1021/acschembio.2c00168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a major threat to human health, as the US mortality rate outweighs those from HIV, tuberculosis, and viral hepatitis combined. In the wake of the COVID-19 pandemic, antibiotic-resistant bacterial infections acquired during hospital stays have increased. Antibiotic adjuvants are a key strategy to combat these bacteria. We have evaluated several small molecule antibiotic adjuvants that have strong potentiation with β-lactam antibiotics and are likely inhibiting a master regulatory kinase, Stk1. Here, we investigated how the lead adjuvant (compound 8) exerts its effects in a more comprehensive manner. We hypothesized that the expression levels of key resistance genes would decrease once cotreated with oxacillin and the adjuvant. Furthermore, bioinformatic analyses would reveal biochemical pathways enriched in differentially expressed genes. RNA-seq analysis showed 176 and 233 genes significantly up- and downregulated, respectively, in response to cotreatment. Gene ontology categories and biochemical pathways that were significantly enriched with downregulated genes involved carbohydrate utilization, such as the citrate cycle and the phosphotransferase system. One of the most populated pathways was S. aureus infection. Results from an interaction network constructed with affected gene products supported the hypothesis that Stk1 is a target of compound 8. This study revealed a dramatic impact of our lead adjuvant on the transcriptome that is consistent with a pleiotropic effect due to Stk1 inhibition. These results point to this antibiotic adjuvant having potential broad therapeutic use in combatting MRSA.
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Affiliation(s)
- Brianna Viering
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Taylor Cunningham
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Ashley King
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Meghan S. Blackledge
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
| | - Heather B. Miller
- Department of Chemistry, High Point University, High Point, North Carolina 27268, United States
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6
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Rom JS, Beenken KE, Ramirez AM, Walker CM, Echols EJ, Smeltzer MS. Limiting protease production plays a key role in the pathogenesis of the divergent clinical isolates of Staphylococcus aureus LAC and UAMS-1. Virulence 2021; 12:584-600. [PMID: 33538230 PMCID: PMC7872036 DOI: 10.1080/21505594.2021.1879550] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/17/2020] [Accepted: 01/10/2021] [Indexed: 01/13/2023] Open
Abstract
Using the USA300, methicillin-resistant Staphylococcus aureus strain LAC, we previously examined the impact of regulatory mutations implicated in biofilm formation on protease production and virulence in a murine sepsis model. Here we examined the impact of these mutations in the USA200, methicillin-sensitive strain UAMS-1. Mutation of agr, mgrA, rot, sarA and sigB attenuated the virulence of UAMS-1. A common characteristic of codY, rot, sigB, and sarA mutants was increased protease production, with mutation of rot having the least impact followed by mutation of codY, sigB and sarA, respectively. Protein A was undetectable in conditioned medium from all four mutants, while extracellular nuclease was only present in the proteolytically cleaved NucA form. The abundance of high molecular weight proteins was reduced in all four mutants. Biofilm formation was reduced in codY, sarA and sigB mutants, but not in the rot mutant. Eliminating protease production partially reversed these phenotypes and enhanced biofilm formation. This was also true in LAC codY, rot, sarA and sigB mutants. Eliminating protease production enhanced the virulence of LAC and UAMS-1 sarA, sigB and rot mutants in a murine sepsis model but did not significantly impact the virulence of the codY mutant in either strain. Nevertheless, these results demonstrate that repressing protease production plays an important role in defining critical phenotypes in diverse clinical isolates of S. aureus and that Rot, SigB and SarA play critical roles in this regard.
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Affiliation(s)
- Joseph S. Rom
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Karen E. Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Aura M. Ramirez
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Christopher M. Walker
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Ethan J. Echols
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Mark S. Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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7
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Wang B, Duan J, Jin Y, Zhan Q, Xu Y, Zhao H, Wang X, Rao L, Guo Y, Yu F. Functional Insights of MraZ on the Pathogenicity of Staphylococcus aureus. Infect Drug Resist 2021; 14:4539-4551. [PMID: 34754202 PMCID: PMC8572050 DOI: 10.2147/idr.s332777] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/08/2021] [Indexed: 01/08/2023] Open
Abstract
Introduction In recent years, multidrug-resistant methicillin-resistant Staphylococcus aureus has become increasingly prevalent, which raised a huge challenge to antibiotic treatment of infectious diseases. The anti-virulence strategy targeting virulent factors is a promising novel therapy for S. aureus infection. The virulence mechanism of S. aureus was needed to explore deeply to develop more targets and improve the effectiveness of anti-virulence strategies. Results In this study, we found mraZ was highly conserved in S. aureus, and its production is homologous with the MraZ of Escherichia coli, a transcriptional regulator involved in the growth and cell division of E. coli. To investigate the function of mraZ in S. aureus, we constructed a MW2 mraZ deletion mutant and its complementary mutant for virulence comparison. Although no remarkable influence on the growth, the mraZ deletion mutant led to significantly reduced resistance to human neutrophils and decreased virulence in Galleria mellonella model as well as mouse skin and soft tissue infection models, indicating its essential contribution to virulence and immune evasion to support the pathogenicity of S. aureus infection. RNA-Seq and quantitative RT-qPCR revealed that MraZ is a multi-functional regulator; it involves in diverse biological processes and can up-regulate the expression of various virulence genes by agr and sarA. Conclusion mraZ plays vital roles in the pathyogenicity of S. aureus via regulating many virulence genes. It may be an attractive target for anti-virulence therapy of S. aureus.
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Affiliation(s)
- Bingjie Wang
- Department of Clinical Laboratory, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China
| | - Jingjing Duan
- Department of Clinical Laboratory, Renmin Hospital, Hubei University of Medicine, Hubei, People's Republic of China
| | - Ye Jin
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Qing Zhan
- Jiangxi Provincial Key Laboratory of Preventive Medicine, School of Public Health, Nanchang University, Nanchang, People's Republic of China
| | - Yanlei Xu
- Jiangxi Provincial Key Laboratory of Preventive Medicine, School of Public Health, Nanchang University, Nanchang, People's Republic of China
| | - Huilin Zhao
- Department of Clinical Laboratory, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China
| | - Xinyi Wang
- Department of Clinical Laboratory, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China
| | - Lulin Rao
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, People's Republic of China
| | - Yinjuan Guo
- Department of Clinical Laboratory, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China
| | - Fangyou Yu
- Department of Clinical Laboratory, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China.,Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China
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8
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Briaud P, Frey A, Marino EC, Bastock RA, Zielinski RE, Wiemels RE, Keogh RA, Murphy ER, Shaw LN, Carroll RK. Temperature Influences the Composition and Cytotoxicity of Extracellular Vesicles in Staphylococcus aureus. mSphere 2021; 6:e0067621. [PMID: 34612674 PMCID: PMC8510519 DOI: 10.1128/msphere.00676-21] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/16/2021] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a pathogenic bacterium but also a commensal of skin and anterior nares in humans. As S. aureus transits from skins/nares to inside the human body, it experiences changes in temperature. The production and content of S. aureus extracellular vesicles (EVs) have been increasingly studied over the past few years, and EVs are increasingly being recognized as important to the infectious process. Nonetheless, the impact of temperature variation on S. aureus EVs has not been studied in detail, as most reports that investigate EV cargoes and host cell interactions are performed using vesicles produced at 37°C. Here, we report that EVs in S. aureus differ in size and protein/RNA cargo depending on the growth temperature used. We demonstrate that the temperature-dependent regulation of vesicle production in S. aureus is mediated by the alpha phenol-soluble modulin peptides (αPSMs). Through proteomic analysis, we observed increased packaging of virulence factors at 40°C, whereas the EV proteome has greater diversity at 34°C. Similar to the protein content, we perform transcriptomic analysis and demonstrate that the RNA cargo also is impacted by temperature. Finally, we demonstrate greater αPSM- and alpha-toxin-mediated erythrocyte lysis with 40°C EVs, but 34°C EVs are more cytotoxic toward THP-1 cells. Together, our study demonstrates that small temperature variations have great impact on EV biogenesis and shape the interaction with host cells. IMPORTANCE Extracellular vesicles (EVs) are lipid bilayer spheres that contain proteins, nucleic acids, and lipids secreted by bacteria. They are involved in Staphylococcus aureus infections, as they package virulence factors and deliver their contents inside host cells. The impact of temperature variations experienced by S. aureus during the infectious process on EVs is unknown. Here, we demonstrate the importance of temperature in vesicle production and packaging. High temperatures promote packaging of virulence factors and increase the protein and lipid concentration but reduce the overall RNA abundance and protein diversity in EVs. The importance of temperature changes is highlighted by the fact that EVs produced at low temperature are more toxic toward macrophages, whereas EVs produced at high temperature display more hemolysis toward erythrocytes. Our research brings new insights into temperature-dependent vesiculation and interaction with the host during S. aureus transition from colonization to virulence.
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Affiliation(s)
- Paul Briaud
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
| | - Andrew Frey
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, Florida, USA
| | - Emily C. Marino
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
| | - Raeven A. Bastock
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
| | | | | | - Rebecca A. Keogh
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
| | - Erin R. Murphy
- Heritage College of Osteopathic Medicine, Department of Biomedical Sciences, Ohio University, Athens, Ohio, USA
- Infectious and Tropical Disease Institute, Ohio University, Athens, Ohio, USA
| | - Lindsey N. Shaw
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, Florida, USA
| | - Ronan K. Carroll
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
- Infectious and Tropical Disease Institute, Ohio University, Athens, Ohio, USA
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9
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Zhang L, Wen B, Bao M, Cheng Y, Mahmood T, Yang W, Chen Q, Lv L, Li L, Yi J, Xie N, Lu C, Tan Y. Andrographolide Sulfonate Is a Promising Treatment to Combat Methicillin-resistant Staphylococcus aureus and Its Biofilms. Front Pharmacol 2021; 12:720685. [PMID: 34603031 PMCID: PMC8481920 DOI: 10.3389/fphar.2021.720685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/29/2021] [Indexed: 01/04/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a drug-resistant pathogen threatening human health and safety. Biofilms are an important cause of its drug resistance and pathogenicity. Inhibition and elimination of biofilms is an important strategy for the treatment of MRSA infection. Andrographolide sulfonate (AS) is an active component of the traditional herbal medicine Andrographis paniculata. This study aims to explore the inhibitory effect and corresponding mechanisms of AS on MRSA and its biofilms. Three doses of AS (6.25, 12.5, and 25 mg/ml) were introduced to MRSA with biofilms. In vitro antibacterial testing and morphological observation were used to confirm the inhibitory effect of AS on MRSA with biofilms. Real-time PCR and metabonomics were used to explore the underlying mechanisms of the effect by studying the expression of biofilm-related genes and endogenous metabolites. AS displayed significant anti-MRSA activity, and its minimum inhibitory concentration was 50 μg/ml. Also, AS inhibited biofilms and improved biofilm permeability. The mechanisms are mediated by the inhibition of the expression of genes, such as quorum sensing system regulatory genes (agrD and sarA), microbial surface components–recognizing adhesion matrix genes (clfA and fnbB), intercellular adhesion genes (icaA, icaD, and PIA), and a gene related to cellular eDNA release (cidA), and the downregulation of five biofilm-related metabolites, including anthranilic acid, D-lactic acid, kynurenine, L-homocitrulline, and sebacic acid. This study provided valuable evidence for the activity of AS against MRSA and its biofilms and extended the methods to combat MRSA infection.
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Affiliation(s)
- Lulu Zhang
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China.,Key Laboratory for Research on Active Ingredients in Natural Medicine of Jiangxi Province, Yichun University, Yichun, China
| | - Bo Wen
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China
| | - Mei Bao
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China.,Key Laboratory for Research on Active Ingredients in Natural Medicine of Jiangxi Province, Yichun University, Yichun, China
| | - Yungchi Cheng
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, United States
| | - Tariq Mahmood
- Department of Plant Sciences, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Weifeng Yang
- Medical Experimental Center, China Academy of Chinese Medical Sciences, Beijing, China
| | - Qing Chen
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China.,Key Laboratory for Research on Active Ingredients in Natural Medicine of Jiangxi Province, Yichun University, Yichun, China
| | - Lang Lv
- Qingfeng Pharmaceutical Co. Ltd., Ganzhou, China
| | - Li Li
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jianfeng Yi
- Key Laboratory for Research on Active Ingredients in Natural Medicine of Jiangxi Province, Yichun University, Yichun, China
| | - Ning Xie
- Qingfeng Pharmaceutical Co. Ltd., Ganzhou, China
| | - Cheng Lu
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yong Tan
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China
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10
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Pyranoanthocyanins Interfering with the Quorum Sensing of Pseudomonas aeruginosa and Staphylococcus aureus. Int J Mol Sci 2021; 22:ijms22168559. [PMID: 34445281 PMCID: PMC8395250 DOI: 10.3390/ijms22168559] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 12/18/2022] Open
Abstract
Bacterial quorum sensing (QS) is a cell-cell communication system that regulates several bacterial mechanisms, including the production of virulence factors and biofilm formation. Thus, targeting microbial QS is seen as a plausible alternative strategy to antibiotics, with potentiality to combat multidrug-resistant pathogens. Many phytochemicals with QS interference activity are currently being explored. Herein, an extract and a compound of bioinspired origin were tested for their ability to inhibit biofilm formation and interfere with the expression of QS-related genes in Pseudomonas aeruginosa and Staphylococcus aureus. The extract, a carboxypyranoanthocyanins red wine extract (carboxypyrano-ant extract), and the pure compound, carboxypyranocyanidin-3-O-glucoside (carboxypyCy-3-glc), did not cause a visible effect on the biofilm formation of the P. aeruginosa biofilms; however, both significantly affected the formation of biofilms by the S. aureus strains, as attested by the crystal violet assay and fluorescence microscopy. Both the extract and the pure compound significantly interfered with the expression of several QS-related genes in the P. aeruginosa and S. aureus biofilms, as per reverse transcription-quantitative polymerase chain reaction (RT-qPCR) results. Indeed, it was possible to conclude that these molecules interfere with QS at distinct stages and in a strain-specific manner. An extract with anti-QS properties could be advantageous because it is easily obtained and could have broad, antimicrobial therapeutic applications if included in topical formulations.
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The Increased Accumulation of Staphylococcus aureus Virulence Factors Is Maximized in a purR Mutant by the Increased Production of SarA and Decreased Production of Extracellular Proteases. Infect Immun 2021; 89:IAI.00718-20. [PMID: 33468580 PMCID: PMC8090970 DOI: 10.1128/iai.00718-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/14/2021] [Indexed: 01/18/2023] Open
Abstract
Mutation of purR was previously shown to enhance the virulence of Staphylococcus aureus in a murine sepsis model, and this cannot be fully explained by increased expression of genes within the purine biosynthesis pathway. Rather, the increased production of specific S. aureus virulence factors, including alpha toxin and the fibronectin-binding proteins, was shown to play an important role. Mutation of purR was also shown previously to result in increased abundance of SarA. Here, we demonstrate by transposon sequencing that mutation of purR in the USA300 strain LAC increases fitness in a biofilm while mutation of sarA has the opposite effect. Therefore, we assessed the impact of sarA on reported purR-associated phenotypes by characterizing isogenic purR, sarA, and sarA/purR mutants. The results confirmed that mutation of purR results in increased abundance of alpha toxin, protein A, the fibronectin-binding proteins, and SarA, decreased production of extracellular proteases, an increased capacity to form a biofilm, and increased virulence in an osteomyelitis model. Mutation of sarA had the opposite effects on all of these phenotypes and, other than bacterial burdens in the bone, all of the phenotypes of sarA/purR mutants were comparable to those of sarA mutants. Limiting the production of extracellular proteases reversed all of the phenotypes of sarA mutants and most of those of sarA/purR mutants. We conclude that a critical component defining the virulence of a purR mutant is the enhanced production of SarA, which limits protease production to an extent that promotes the accumulation of critical S. aureus virulence factors.
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Abstract
Staphylococcus aureus controls the progression of infection through the coordinated production of extracellular proteases, which selectively modulate virulence determinant stability. This is evidenced by our previous finding that a protease-null strain has a hypervirulent phenotype in a murine model of sepsis, resulting from the unchecked accumulation of virulence factors. Here, we dissect the individual roles of these proteases by constructing and assessing the pathogenic potential of a combinatorial protease mutant library. When strains were constructed bearing increasing numbers of secreted proteases, we observed a variable impact on infectious capacity, where some exhibited hypervirulence, while others phenocopied the wild-type. The common thread for hypervirulent strains was that each lacked both aureolysin and staphopain A. Upon assessment, we found that the combined loss of these two enzymes alone was necessary and sufficient to engender hypervirulence. Using proteomics, we identified a number of important secreted factors, including SPIN, LukA, Sbi, SEK, and PSMα4, as well as an uncharacterized chitinase-related protein (SAUSA300_0964), to be overrepresented in both the aur scpA and the protease-null mutants. When assessing the virulence of aur scpA SAUSA300_0964 and aur scpA lukA mutants, we found that hypervirulence was completely eliminated, whereas aur scpA spn and aur scpA sek strains elicited aggressive infections akin to the protease double mutant. Collectively, our findings shed light on the influence of extracellular proteases in controlling the infectious process and identifies SAUSA300_0964 as an important new component of the S. aureus virulence factor arsenal.IMPORTANCE A key feature of the pathogenic success of S. aureus is the myriad virulence factors encoded within its genome. These are subject to multifactorial control, ensuring their timely production only within an intended infectious niche. A key node in this network of control is the secreted proteases of S. aureus, who specifically and selectively modulate virulence factor stability. In our previous work we demonstrated that deletion of all 10 secreted proteases results in hypervirulence, since virulence factors exist unchecked, leading to overly aggressive infections. Here, using a combinatorial collection of protease mutants, we reveal that deletion of aureolysin and staphopain A is necessary and sufficient to elicit hypervirulence. Using proteomic techniques, we identify the collection of virulence factors that accumulate in hypervirulent protease mutants, and demonstrate that a well-known toxin (LukA) and an entirely novel secreted element (SAUSA300_0964) are the leading contributors to deadly infections observed in protease-lacking strains.
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Horvatek P, Salzer A, Hanna AMF, Gratani FL, Keinhörster D, Korn N, Borisova M, Mayer C, Rejman D, Mäder U, Wolz C. Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes. PLoS Genet 2020; 16:e1009282. [PMID: 33378356 PMCID: PMC7802963 DOI: 10.1371/journal.pgen.1009282] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 01/12/2021] [Accepted: 11/18/2020] [Indexed: 11/30/2022] Open
Abstract
The stringent response is characterized by the synthesis of the messenger molecules pppGpp, ppGpp or pGpp (here collectively designated (pp)pGpp). The phenotypic consequences resulting from (pp)pGpp accumulation vary among species and can be mediated by different underlying mechanisms. Most genome-wide analyses have been performed under stress conditions, which often mask the immediate effects of (pp)pGpp-mediated regulatory circuits. In Staphylococcus aureus, (pp)pGpp can be synthesized via the RelA-SpoT-homolog, RelSau upon amino acid limitation or via one of the two small (pp)pGpp synthetases RelP or RelQ upon cell wall stress. We used RNA-Seq to compare the global effects in response to induction of the synthetase of rel-Syn (coding for the enzymatic region of RelSau) or relQ without the need to apply additional stress conditions. Induction of rel-Syn resulted in changes in the nucleotide pool similar to induction of the stringent response via the tRNA synthetase inhibitor mupirocin: a reduction in the GTP pool, an increase in the ATP pool and synthesis of pppGpp, ppGpp and pGpp. Induction of all three enzymes resulted in similar changes in the transcriptome. However, RelQ was less active than Rel-Syn and RelP, indicating strong restriction of its (pp)pGpp-synthesis activity in vivo. (pp)pGpp induction resulted in the downregulation of many genes involved in protein and RNA/DNA metabolism. Many of the (pp)pGpp upregulated genes are part of the GTP sensitive CodY regulon and thus likely regulated through lowering of the GTP pool. New CodY independent transcriptional changes were detected including genes involved in the SOS response, iron storage (e.g. ftnA, dps), oxidative stress response (e.g., perR, katA, sodA) and the psmα1–4 and psmß1-2 operons coding for cytotoxic, phenol soluble modulins (PSMs). Analyses of the ftnA, dps and psm genes in different regulatory mutants revealed that their (pp)pGpp-dependent regulation can occur independent of the regulators PerR, Fur, SarA or CodY. Moreover, psm expression is uncoupled from expression of the quorum sensing system Agr, the main known psm activator. The expression of central genes of the oxidative stress response protects the bacteria from anticipated ROS stress derived from PSMs or exogenous sources. Thus, we identified a new link between the stringent response and oxidative stress in S. aureus that is likely crucial for survival upon phagocytosis. Most bacteria make use of the second messenger (pp)pGpp to reprogram bacterial metabolism under nutrient-limiting conditions. In the human pathogen Staphylococcus aureus, (pp)pGpp plays an important role in virulence, phagosomal escape and antibiotic tolerance. Here, we analyzed the immediate consequences of (pp)pGpp synthesis upon transcriptional induction of the (pp)pGpp-producing enzymes Rel, RelP or RelQ. (pp)pGpp synthesis provokes immediate changes in the nucleotide pool and severely impacts the expression of hundreds of genes. A main consequence of (pp)pGpp synthesis in S. aureus is the induction of ROS-inducing toxic phenol soluble modulins (PSMs) and simultaneous expression of the detoxifying system to protect the producer. This mechanism is likely of special advantage for the pathogen after phagocytosis.
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Affiliation(s)
- Petra Horvatek
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Germany
| | - Andrea Salzer
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Germany
| | | | - Fabio Lino Gratani
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Germany
- Quantitative Proteomics & Proteome Center Tuebingen, University of Tuebingen, Germany
| | - Daniela Keinhörster
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Germany
| | - Natalya Korn
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Germany
| | - Marina Borisova
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Germany
| | - Christoph Mayer
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Germany
| | - Dominik Rejman
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Ulrike Mäder
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Germany
- * E-mail:
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Sahukhal GS, Tucci M, Benghuzzi H, Wilson G, Elasri MO. The role of the msaABCR operon in implant-associated chronic osteomyelitis in Staphylococcus aureus USA300 LAC. BMC Microbiol 2020; 20:324. [PMID: 33109085 PMCID: PMC7590495 DOI: 10.1186/s12866-020-01964-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 09/02/2020] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The msaABCR operon regulates several staphylococcal phenotypes such as biofilm formation, capsule production, protease production, pigmentation, antibiotic resistance, and persister cells formation. The msaABCR operon is required for maintaining the cell wall integrity via affecting peptidoglycan cross-linking. The msaABCR operon also plays a role in oxidative stress defense mechanism, which is required to facilitate persistent and recurrent staphylococcal infections. Staphylococcus aureus is the most frequent cause of chronic implant-associated osteomyelitis (OM). The CA-MRSA USA300 strains are predominant in the United States and cause severe infections, including bone and joint infections. RESULTS The USA300 LAC strain caused significant bone damage, as evidenced by the presence of severe bone necrosis with multiple foci of sequestra and large numbers of multinucleated osteoclasts. Intraosseous survival and biofilm formation on the K-wires by USA300 LAC strains was pronounced. However, the msaABCR deletion mutant was attenuated. We observed minimal bone necrosis, with no evidence of intramedullary abscess and/or fibrosis, along reduced intraosseous bacterial population and significantly less biofilm formation on the K-wires by the msaABCR mutant. microCT analysis of infected bone showed significant bone loss and damage in the USA300 LAC and complemented strain, whereas the msaABCR mutant's effect was reduced. In addition, we observed increased osteoblasts response and new bone formation around the K-wires in the bone infected by the msaABCR mutant. Whole-cell proteomics analysis of msaABCR mutant cells showed significant downregulation of proteins, cell adhesion factors, and virulence factors that interact with osteoblasts and are associated with chronic OM caused by S. aureus. CONCLUSION This study showed that deletion of msaABCR operon in USA300 LAC strain lead to defective biofilm in K-wire implants, decreased intraosseous survival, and reduced cortical bone destruction. Thus, msaABCR plays a role in implant-associated chronic osteomyelitis by regulating extracellular proteases, cell adhesions factors and virulence factors. However additional studies are required to further define the contribution of msaABCR-regulated molecules in osteomyelitis pathogenesis.
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Affiliation(s)
- Gyan S Sahukhal
- Present Address: Center for Molecular and Cellular Biosciences, The University of Southern Mississippi, 118 College Drive # 5018, Hattiesburg, MS, 39406, USA.
| | - Michelle Tucci
- Department of Orthopaedics, University of Mississippi Medical Center, Jackson, MS, USA
| | - Hamed Benghuzzi
- Department of Orthopaedics, University of Mississippi Medical Center, Jackson, MS, USA
| | - Gerri Wilson
- Department of Orthopaedics, University of Mississippi Medical Center, Jackson, MS, USA
| | - Mohamed O Elasri
- Present Address: Center for Molecular and Cellular Biosciences, The University of Southern Mississippi, 118 College Drive # 5018, Hattiesburg, MS, 39406, USA
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Butrico CE, Cassat JE. Quorum Sensing and Toxin Production in Staphylococcus aureus Osteomyelitis: Pathogenesis and Paradox. Toxins (Basel) 2020; 12:toxins12080516. [PMID: 32806558 PMCID: PMC7471978 DOI: 10.3390/toxins12080516] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/04/2020] [Accepted: 08/10/2020] [Indexed: 01/18/2023] Open
Abstract
Staphylococcus aureus is a Gram-positive pathogen capable of infecting nearly every vertebrate organ. Among these tissues, invasive infection of bone (osteomyelitis) is particularly common and induces high morbidity. Treatment of osteomyelitis is notoriously difficult and often requires debridement of diseased bone in conjunction with prolonged antibiotic treatment to resolve infection. During osteomyelitis, S. aureus forms characteristic multicellular microcolonies in distinct niches within bone. Virulence and metabolic responses within these multicellular microcolonies are coordinated, in part, by quorum sensing via the accessory gene regulator (agr) locus, which allows staphylococcal populations to produce toxins and adapt in response to bacterial density. During osteomyelitis, the Agr system significantly contributes to dysregulation of skeletal homeostasis and disease severity but may also paradoxically inhibit persistence in the host. Moreover, the Agr system is subject to complex crosstalk with other S. aureus regulatory systems, including SaeRS and SrrAB, which can significantly impact the progression of osteomyelitis. The objective of this review is to highlight Agr regulation, its implications on toxin production, factors that affect Agr activation, and the potential paradoxical influences of Agr regulation on disease progression during osteomyelitis.
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Affiliation(s)
- Casey E. Butrico
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
| | - James E. Cassat
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation (VI4), Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Correspondence: ; Tel.: +1-615-936-6494
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Vollaro A, Esposito A, Esposito EP, Zarrilli R, Guaragna A, De Gregorio E. PYED-1 Inhibits Biofilm Formation and Disrupts the Preformed Biofilm of Staphylococcus aureus. Antibiotics (Basel) 2020; 9:E240. [PMID: 32397205 PMCID: PMC7277567 DOI: 10.3390/antibiotics9050240] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 05/04/2020] [Accepted: 05/06/2020] [Indexed: 12/12/2022] Open
Abstract
Pregnadiene-11-hydroxy-16α,17α-epoxy-3,20-dione-1 (PYED-1), a heterocyclic corticosteroid derivative of deflazacort, exhibits broad-spectrum antibacterial activity against Gram-negative and Gram-positive bacteria. Here, we investigated the effect of PYED-1 on the biofilms of Staphylococcus aureus, an etiological agent of biofilm-based chronic infections such as osteomyelitis, indwelling medical device infections, periodontitis, chronic wound infections, and endocarditis. PYED-1 caused a strong reduction in biofilm formation in a concentration dependent manner. Furthermore, it was also able to completely remove the preformed biofilm. Transcriptional analysis performed on the established biofilm revealed that PYED-1 downregulates the expression of genes related to quorum sensing (agrA, RNAIII, hld, psm, and sarA), surface proteins (clfB and fnbB), secreted toxins (hla, hlb, and lukD), and capsular polysaccharides (capC). The expression of genes that encode two main global regulators, sigB and saeR, was also significantly inhibited after treatment with PYED-1. In conclusion, PYED-1 not only effectively inhibited biofilm formation, but also eradicated preformed biofilms of S. aureus, modulating the expression of genes related to quorum sensing, surface and secreted proteins, and capsular polysaccharides. These results indicated that PYED-1 may have great potential as an effective antibiofilm agent to prevent S. aureus biofilm-associated infections.
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Affiliation(s)
- Adriana Vollaro
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy;
| | - Anna Esposito
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy;
| | - Eliana Pia Esposito
- Department of Public Health, University of Naples Federico II, 80131 Naples, Italy; (E.P.E.); (R.Z.)
| | - Raffaele Zarrilli
- Department of Public Health, University of Naples Federico II, 80131 Naples, Italy; (E.P.E.); (R.Z.)
| | - Annalisa Guaragna
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy;
| | - Eliana De Gregorio
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy;
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Johansson C, Rautelin H, Kaden R. Staphylococcus argenteus and Staphylococcus schweitzeri are cytotoxic to human cells in vitro due to high expression of alpha-hemolysin Hla. Virulence 2020; 10:502-510. [PMID: 31131704 PMCID: PMC6550535 DOI: 10.1080/21505594.2019.1620062] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Staphylococcus argenteus and Staphylococcus schweitzeri are newly identified species of the S. aureus-related complex. S. argenteus, as occurring globally and showing significant prevalence and comparable infection and morbidity rates compared to S. aureus, is becoming clinically important. Whole genome sequencing has revealed the presence of several virulence genes but the molecular mechanisms of S. argenteus infection and virulence are largely unknown. Here, we studied the effect of a previously characterized clinical S. argenteus isolate on human cells in vitro. The clinical isolate, together with the S. argenteus type strain MSHR1132T and the S. schweitzeri type strain FSA084T, had a cytotoxic effect on the cells, which showed necrotic cell death after a few hours of treatment. The protein causing the cytotoxic effect was purified and identified by mass spectrometry as alpha-hemolysin, Hla, which is awell-known pore-forming toxin in S.aureus. The cytotoxic effect could be blocked with an antibody against Hla. S.argenteus showed 12–15 fold higher expression levels of hla at the RNA level and 4–6 fold higher expression levels at the protein level compared to S.aureus. The higher expression levels of hla were supported by higher RNA levels of the regulatory factors sarA and saeR. Also, the RNAIII component of the accessory gene regulator (agr) quorum sensing system was 8,000–10,000 fold higher in the S.argenteus isolates compared to S.aureus. This is the first study on the effect of S.argenteus on ahuman cell line and strengthens the idea of significant virulence of S.argenteus.
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Affiliation(s)
- Cecilia Johansson
- a Clinical Microbiology, Department of Medical Sciences , Uppsala University , Uppsala , Sweden
| | - Hilpi Rautelin
- a Clinical Microbiology, Department of Medical Sciences , Uppsala University , Uppsala , Sweden
| | - René Kaden
- a Clinical Microbiology, Department of Medical Sciences , Uppsala University , Uppsala , Sweden
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Ramirez AM, Byrum SD, Beenken KE, Washam C, Edmondson RD, Mackintosh SG, Spencer HJ, Tackett AJ, Smeltzer MS. Exploiting Correlations between Protein Abundance and the Functional Status of saeRS and sarA To Identify Virulence Factors of Potential Importance in the Pathogenesis of Staphylococcus aureus Osteomyelitis. ACS Infect Dis 2020; 6:237-249. [PMID: 31722523 PMCID: PMC7294808 DOI: 10.1021/acsinfecdis.9b00291] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We used a murine model of postsurgical osteomyelitis (OM) to evaluate the relative virulence of the Staphylococcus aureus strain LAC and five isogenic variants that differ in the functional status of saeRS and sarA relative to each other. LAC and a variant in which saeRS activity is increased (saeC) were comparably virulent to each other, while ΔsaeRS, ΔsarA, ΔsaeRS/ΔsarA, and saeC/ΔsarA mutants were all attenuated to a comparable degree. Phenotypic comparisons including a mass-based proteomics approach that allowed us to assess the number and abundance of full-length proteins suggested that mutation of saeRS attenuates virulence in our OM model owing primarily to the decreased production of S. aureus virulence factors, while mutation of sarA does so owing to protease-mediated degradation of these same virulence factors. This was confirmed by demonstrating that eliminating protease production restored virulence to a greater extent in a LAC sarA mutant than in the isogenic saeRS mutant. Irrespective of the mechanism involved, mutation of saeRS or sarA was shown to result in reduced accumulation of virulence factors of potential importance. Thus, using our proteomics approach we correlated the abundance of specific proteins with virulence in these six strains and identified 14 proteins that were present in a significantly increased amount (log2 ≥ 5.0) in both virulent strains by comparison to all four attenuated strains. We examined biofilm formation and virulence in our OM model using a LAC mutant unable to produce one of these 14 proteins, specifically staphylocoagulase. The results confirmed that mutation of coa limits biofilm formation and, to a lesser extent, virulence in our OM model, although in both cases the limitation was reduced by comparison to the isogenic sarA mutant.
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Affiliation(s)
- Aura M. Ramirez
- Department of Microbiology
and Immunology, College of Medicine, University
of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 511, Little Rock, Arkansas 72205, United States
| | - Stephanie D. Byrum
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 516, Little Rock, Arkansas 72205, United States,Arkansas
Children’s Research Institute, 1 Children’s Way, Little Rock, Arkansas 72202, United States
| | - Karen E. Beenken
- Department of Microbiology
and Immunology, College of Medicine, University
of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 511, Little Rock, Arkansas 72205, United States
| | - Charity Washam
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 516, Little Rock, Arkansas 72205, United States,Arkansas
Children’s Research Institute, 1 Children’s Way, Little Rock, Arkansas 72202, United States
| | - Rick D. Edmondson
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 516, Little Rock, Arkansas 72205, United States
| | - Samuel G. Mackintosh
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 516, Little Rock, Arkansas 72205, United States
| | - Horace J. Spencer
- Department of Biostatistics, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Little Rock, Arkansas 72205, United States
| | - Alan J. Tackett
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 516, Little Rock, Arkansas 72205, United States,Arkansas
Children’s Research Institute, 1 Children’s Way, Little Rock, Arkansas 72202, United States
| | - Mark S. Smeltzer
- Department of Microbiology
and Immunology, College of Medicine, University
of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 511, Little Rock, Arkansas 72205, United States,Department
of Orthopaedic Surgery, University of Arkansas
for Medical Sciences, 4301 W. Markham Street, Slot 531, Little Rock, Arkansas 72205, United States,Phone: 501-686-7958. E-mail:
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The Impacts of msaABCR on sarA-Associated Phenotypes Are Different in Divergent Clinical Isolates of Staphylococcus aureus. Infect Immun 2020; 88:IAI.00530-19. [PMID: 31740526 PMCID: PMC6977130 DOI: 10.1128/iai.00530-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 11/07/2019] [Indexed: 12/27/2022] Open
Abstract
The staphylococcal accessory regulator (sarA) plays an important role in Staphylococcus aureus infections, including osteomyelitis, and the msaABCR operon has been implicated as an important factor in modulating expression of sarA Thus, we investigated the contribution of msaABCR to sarA-associated phenotypes in the S. aureus clinical isolates LAC and UAMS-1. Mutation of msaABCR resulted in reduced production of SarA and a reduced capacity to form a biofilm in both strains. Biofilm formation was enhanced in a LAC msa mutant by restoring the production of SarA, but this was not true in a UAMS-1 msa mutant. Similarly, extracellular protease production was increased in a LAC msa mutant but not a UAMS-1 msa mutant. This difference was reflected in the accumulation and distribution of secreted virulence factors and in the impact of extracellular proteases on biofilm formation in a LAC msa mutant. Most importantly, it was reflected in the relative impact of mutating msa as assessed in a murine osteomyelitis model, which had a significant impact in LAC but not in UAMS-1. In contrast, mutation of sarA had a greater impact on all of these in vitro and in vivo phenotypes than mutation of msaABCR, and it did so in both LAC and UAMS-1. These results suggest that, at least in osteomyelitis, it would be therapeutically preferable to target sarA rather than msaABCR to achieve the desired clinical result, particularly in the context of divergent clinical isolates of S. aureus.
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Abstract
The complex regulatory role of the proteases necessitates very tight coordination and control of their expression. While this process has been well studied, a major oversight has been the consideration of proteases as a single entity rather than as 10 enzymes produced from four different promoters. As such, in this study, we comprehensively characterized the regulation of each protease promoter, discovering vast differences in the way each protease operon is controlled. Additionally, we broaden the picture of protease regulation using a global screen to identify novel loci controlling protease activity, uncovering a cadre of new effectors of protease expression. The impact of these elements on the activity of proteases and known regulators was characterized by producing a comprehensive regulatory circuit that emphasizes the complexity of protease regulation in Staphylococcus aureus. A primary function of the extracellular proteases of Staphylococcus aureus is to control the progression of infection by selectively modulating the stability of virulence factors. Consequently, a regulatory network exists to titrate protease abundance/activity to influence the accumulation, or lack thereof, of individual virulence factors. Herein, we comprehensively map this system, exploring the regulation of the four protease loci by known and novel factors. In so doing, we determined that seven major elements (SarS, SarR, Rot, MgrA, CodY, SaeR, and SarA) form the primary network of control, with the latter three being the most powerful. We note that expression of aureolysin is largely repressed by these factors, while the spl operon is subject to the strongest upregulation of any protease loci, particularly by SarR and SaeR. Furthermore, when exploring scpA expression, we find it to be profoundly influenced in opposing fashions by SarA (repressor) and SarR (activator). We also present the screening of >100 regulator mutants of S. aureus, identifying 7 additional factors (ArgR2, AtlR, MntR, Rex, XdrA, Rbf, and SarU) that form a secondary circuit of protease control. Primarily, these elements serve as activators, although we reveal XdrA as a new repressor of protease expression. With the exception or ArgR2, each of the new effectors appears to work through the primary network of regulation to influence protease production. Collectively, we present a comprehensive regulatory circuit that emphasizes the complexity of protease regulation and suggest that its existence speaks to the importance of these enzymes to S. aureus physiology and pathogenic potential. IMPORTANCE The complex regulatory role of the proteases necessitates very tight coordination and control of their expression. While this process has been well studied, a major oversight has been the consideration of proteases as a single entity rather than as 10 enzymes produced from four different promoters. As such, in this study, we comprehensively characterized the regulation of each protease promoter, discovering vast differences in the way each protease operon is controlled. Additionally, we broaden the picture of protease regulation using a global screen to identify novel loci controlling protease activity, uncovering a cadre of new effectors of protease expression. The impact of these elements on the activity of proteases and known regulators was characterized by producing a comprehensive regulatory circuit that emphasizes the complexity of protease regulation in Staphylococcus aureus.
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Contribution of hla Regulation by SaeR to Staphylococcus aureus USA300 Pathogenesis. Infect Immun 2019; 87:IAI.00231-19. [PMID: 31209148 DOI: 10.1128/iai.00231-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [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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22
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The purine biosynthesis regulator PurR moonlights as a virulence regulator in Staphylococcus aureus. Proc Natl Acad Sci U S A 2019; 116:13563-13572. [PMID: 31217288 DOI: 10.1073/pnas.1904280116] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The pathogen Staphylococcus aureus colonizes and infects a variety of different sites within the human body. To adapt to these different environments, S. aureus relies on a complex and finely tuned regulatory network. While some of these networks have been well-elucidated, the functions of more than 50% of the transcriptional regulators in S. aureus remain unexplored. Here, we assess the contribution of the LacI family of metabolic regulators to staphylococcal virulence. We found that inactivating the purine biosynthesis regulator purR resulted in a strain that was acutely virulent in bloodstream infection models in mice and in ex vivo models using primary human neutrophils. Remarkably, these enhanced pathogenic traits are independent of purine biosynthesis, as the purR mutant was still highly virulent in the presence of mutations that disrupt PurR's canonical role. Through the use of transcriptomics coupled with proteomics, we revealed that a number of virulence factors are differentially regulated in the absence of purR Indeed, we demonstrate that PurR directly binds to the promoters of genes encoding virulence factors and to master regulators of virulence. These results guided us into further ex vivo and in vivo studies, where we discovered that S. aureus toxins drive the death of human phagocytes and mice, whereas the surface adhesin FnbA contributes to the increased bacterial burden observed in the purR mutant. Thus, S. aureus repurposes a metabolic regulator to directly control the expression of virulence factors, and by doing so, tempers its pathogenesis.
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Abstract
Staphylococcus aureus is a Gram-positive opportunistic pathogen that has evolved a complex regulatory network to control virulence. One of the main functions of this interconnected network is to sense various environmental cues and respond by altering the production of virulence factors necessary for survival in the host, including cell surface adhesins and extracellular enzymes and toxins. Of these S. aureus regulatory systems, one of the best studied is the accessory gene regulator (agr), which is a quorum-sensing system that senses the local concentration of a cyclic peptide signaling molecule. This system allows S. aureus to sense its own population density and translate this information into a specific gene expression pattern. Besides agr, this pathogen uses other two-component systems to sense specific cues and coordinates responses with cytoplasmic regulators of the SarA protein family and alternative sigma factors. These divergent regulatory systems integrate the various environmental and host-derived signals into a network that ensures optimal pathogen response to the changing conditions. This article gives an overview of the most important and best-studied S. aureus regulatory systems and summarizes the functions of these regulators during host interactions. The regulatory systems discussed include the agr quorum-sensing system; the SaeRS, SrrAB, and ArlRS two-component systems, the cytoplasmic SarA-family regulators (SarA, Rot, and MgrA); and the alternative sigma factors (SigB and SigH).
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Wu X, Yang M, Fang X, Zhen S, Zhang J, Yang X, Qiao L, Yang Y, Zhang C. Expression and regulation of phenol-soluble modulins and enterotoxins in foodborne Staphylococcus aureus. AMB Express 2018; 8:187. [PMID: 30467730 PMCID: PMC6250609 DOI: 10.1186/s13568-018-0717-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 11/17/2018] [Indexed: 12/15/2022] Open
Abstract
Although high levels of staphylococcal phenol-soluble modulins (PSMs) in clinical methicillin-resistant Staphylococcus aureus (MRSA) has been shown to correlate with bacterial virulence, the PSMs expression in foodborne Staphylococcus aureus (S. aureus), as well as its association with staphylococcal food poisoning (SFP) was not yet clear. We collected a panel of 350 foodborne and 127 clinic-derived S. aureus strains and compared their PSMs expression. Overall, foodborne strains exhibited higher PSMs than clinical isolates, indicating a potential pathological significance of PSMs in staphylococcal food contamination. Furthermore, PSMs expression and staphylococcal enterotoxins (SEs) levels in relation to antibiotic sensitive and resistant strains were analysed. While the co-expression of PSMs and SEs was confirmed, one typical foodborne strain simultaneously yielding PSMs, SEB and SED was selected. By comparing this wildtype strain to a series of gene-deficient mutants, we concluded that PSMs and SEs expressions both relied on staphylococcal accessory regulator A initiation in the early stage of accessory gene regulator control, yet their succedent regulations differentiated to RNAIII-dependent and independent, respectively. These data provided preliminary insight into PSMs and SEs expression in foodborne S. aureus, and may guide the further studies on PSMs effects in SFP.
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25
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Byrum S, Loughran AJ, Beenken KE, Orr LM, Storey AJ, Mackintosh SG, Edmondson RD, Tackett AJ, Smeltzer MS. Label-Free Proteomic Approach to Characterize Protease-Dependent and -Independent Effects of sarA Inactivation on the Staphylococcus aureus Exoproteome. J Proteome Res 2018; 17:3384-3395. [PMID: 30209945 PMCID: PMC6209314 DOI: 10.1021/acs.jproteome.8b00288] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The staphylococcal accessory regulator A ( sarA) impacts the extracellular accumulation of Staphylococcus aureus virulence factors at the level of intracellular production and extracellular protease-mediated degradation. We previously used a proteomics approach that measures protein abundance of all proteoforms to demonstrate that mutation of sarA results in increased levels of extracellular proteases and assesses the impact of this on the accumulation of S. aureus exoproteins. Our previous approach was limited as it did not take into account that large, stable proteolytic products from a given protein could result in false negatives when quantified by total proteoforms. Here, our goal was to use an expanded proteomics approach utilizing a dual quantitative method for measuring abundance at both the total proteoform and full-length exoprotein levels to alleviate these false negatives and thereby provide for characterization of protease-dependent and -independent effects of sarA mutation on the S. aureus exoproteome. Proteins present in conditioned medium from overnight, stationary phase cultures of the USA300 strain LAC, an isogenic sarA mutant, and a sarA mutant unable to produce any of the known extracellular proteases ( sarA/protease) were resolved using one-dimensional gel electrophoresis. Quantitative proteomic comparisons of sarA versus sarA/protease mutants identified proteins that were cleaved in a protease-dependent manner owing to mutation of sarA, and comparisons of sarA/protease mutant versus the LAC parent strain identified proteins in which abundance was altered in a sarA mutant in a protease-independent manner. Furthermore, the proteins uniquely identified by the full-length data analysis approach eliminated false negatives observed in the total proteoform analysis. This expanded approach provided for a more comprehensive analysis of the impact of mutating sarA on the S. aureus exoproteome.
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Affiliation(s)
- Stephanie
D. Byrum
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States,Arkansas
Children’s Research Institute, 13 Children’s Way, Little Rock, Arkansas 72202, United States
| | - Allister J. Loughran
- Department
of Microbiology and Immunology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Karen E. Beenken
- Department
of Microbiology and Immunology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Lisa M. Orr
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Aaron J. Storey
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Samuel G. Mackintosh
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Ricky D. Edmondson
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
| | - Alan J. Tackett
- Department
of Biochemistry and Molecular Biology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States,Arkansas
Children’s Research Institute, 13 Children’s Way, Little Rock, Arkansas 72202, United States,E-mail:
| | - Mark S. Smeltzer
- Department
of Microbiology and Immunology, University
of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States,E-mail: , Phone: (501) 686-7958
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Rom JS, Atwood DN, Beenken KE, Meeker DG, Loughran AJ, Spencer HJ, Lantz TL, Smeltzer MS. Impact of Staphylococcus aureus regulatory mutations that modulate biofilm formation in the USA300 strain LAC on virulence in a murine bacteremia model. Virulence 2017; 8:1776-1790. [PMID: 28910576 PMCID: PMC5810510 DOI: 10.1080/21505594.2017.1373926] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Staphylococcus aureus causes acute and chronic forms of infection, the latter often associated with formation of a biofilm. It has previously been demonstrated that mutation of atl, codY, rot, sarA, and sigB limits biofilm formation in the USA300 strain LAC while mutation of agr, fur, and mgrA has the opposite effect. Here we used a murine sepsis model to assess the impact of these same loci in acute infection. Mutation of agr, atl, and fur had no impact on virulence, while mutation of mgrA and rot increased virulence. In contrast, mutation of codY, sarA, and sigB significantly attenuated virulence. Mutation of sigB resulted in reduced accumulation of AgrA and SarA, while mutation of sarA resulted in reduced accumulation of AgrA, but this cannot account for the reduced virulence of sarA or sigB mutants because the isogenic agr mutant was not attenuated. Indeed, as assessed by accumulation of alpha toxin and protein A, all of the mutants we examined exhibited unique phenotypes by comparison to an agr mutant and to each other. Attenuation of the sarA, sigB and codY mutants was correlated with increased production of extracellular proteases and global changes in extracellular protein profiles. These results suggest that the inability to repress the production of extracellular proteases plays a key role in attenuating the virulence of S. aureus in acute as well as chronic, biofilm-associated infections, thus opening up the possibility that strategies aimed at the de-repression of protease production could be used to broad therapeutic advantage. They also suggest that the impact of codY, sarA, and sigB on protease production occurs via an agr-independent mechanism.
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Affiliation(s)
- Joseph S Rom
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Danielle N Atwood
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Karen E Beenken
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Daniel G Meeker
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Allister J Loughran
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Horace J Spencer
- b Department of Biostatistics , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Tamara L Lantz
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Mark S Smeltzer
- a Department of Microbiology and Immunology , University of Arkansas for Medical Sciences , Little Rock , AR , USA.,c Department of Orthopaedic Surgery , University of Arkansas for Medical Sciences , Little Rock , AR , USA.,d Department of Pathology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
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Staphylococcus aureus Infection Reduces Nutrition Uptake and Nucleotide Biosynthesis in a Human Airway Epithelial Cell Line. Metabolites 2016; 6:metabo6040041. [PMID: 27834866 PMCID: PMC5192447 DOI: 10.3390/metabo6040041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 10/28/2016] [Accepted: 11/02/2016] [Indexed: 11/16/2022] Open
Abstract
The Gram positive opportunistic human pathogen Staphylococcus aureus induces a variety of diseases including pneumonia. S. aureus is the second most isolated pathogen in cystic fibrosis patients and accounts for a large proportion of nosocomial pneumonia. Inside the lung, the human airway epithelium is the first line in defence with regard to microbial recognition and clearance as well as regulation of the immune response. The metabolic host response is, however, yet unknown. To address the question of whether the infection alters the metabolome and metabolic activity of airway epithelial cells, we used a metabolomics approach. The nutrition uptake by the human airway epithelial cell line A549 was monitored over time by proton magnetic resonance spectroscopy (1H-NMR) and the intracellular metabolic fingerprints were investigated by gas chromatography and high performance liquid chromatography (GC-MS) and (HPLC-MS). To test the metabolic activity of the host cells, glutamine analogues and labelled precursors were applied after the infection. We found that A549 cells restrict uptake of essential nutrients from the medium after S. aureus infection. Moreover, the infection led to a shutdown of the purine and pyrimidine synthesis in the A549 host cell, whereas other metabolic routes such as the hexosamine biosynthesis pathway remained active. In summary, our data show that the infection with S. aureus negatively affects growth, alters the metabolic composition and specifically impacts the de novo nucleotide biosynthesis in this human airway epithelial cell model.
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Gao P, Wang Y, Villanueva I, Ho PL, Davies J, Kao RYT. Construction of a Multiplex Promoter Reporter Platform to Monitor Staphylococcus aureus Virulence Gene Expression and the Identification of Usnic Acid as a Potent Suppressor of psm Gene Expression. Front Microbiol 2016; 7:1344. [PMID: 27625639 PMCID: PMC5004274 DOI: 10.3389/fmicb.2016.01344] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/15/2016] [Indexed: 12/05/2022] Open
Abstract
As antibiotic resistance becomes phenomenal, alternative therapeutic strategies for bacterial infections such as anti-virulence treatments have been advocated. We have constructed a total of 20 gfp-luxABCDE dual-reporter plasmids with selected promoters from S. aureus virulence-associated genes. The plasmids were introduced into various S. aureus strains to establish a gfp-lux based multiplex promoter reporter platform for monitoring S. aureus virulence gene expressions in real time to identify factors or compounds that may perturb virulence of S. aureus. The gene expression profiles monitored by luminescence correlated well with qRT-PCR results and extrinsic factors including carbon dioxide and some antibiotics were shown to suppress or induce the expression of virulence factors in this platform. Using this platform, sub-inhibitory ampicillin was shown to be a potent inducer for the expression of many virulence factors in S. aureus. Bacterial adherence and invasion assays using mammalian cells were employed to measure S. aureus virulence induced by ampicillin. The platform was used for screening of natural extracts that perturb the virulence of S. aureus and usnic acid was identified to be a potent repressor for the expression of psm.
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Affiliation(s)
- Peng Gao
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong KongHong Kong, Hong Kong; Li Ka Shing Faculty of Medicine, The Research Centre of Infection and Immunology, The University of Hong KongHong Kong, Hong Kong
| | - Yanli Wang
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong KongHong Kong, Hong Kong; Li Ka Shing Faculty of Medicine, The Research Centre of Infection and Immunology, The University of Hong KongHong Kong, Hong Kong
| | - Iván Villanueva
- Department of Microbiology and Immunology, The University of British Columbia Vancouver, BC, Canada
| | - Pak Leung Ho
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong KongHong Kong, Hong Kong; Li Ka Shing Faculty of Medicine, The Research Centre of Infection and Immunology, The University of Hong KongHong Kong, Hong Kong; State Key Laboratory for Emerging Infectious Disease, The University of Hong KongHong Kong, Hong Kong
| | - Julian Davies
- Department of Microbiology and Immunology, The University of British Columbia Vancouver, BC, Canada
| | - Richard Yi Tsun Kao
- Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong KongHong Kong, Hong Kong; Li Ka Shing Faculty of Medicine, The Research Centre of Infection and Immunology, The University of Hong KongHong Kong, Hong Kong; State Key Laboratory for Emerging Infectious Disease, The University of Hong KongHong Kong, Hong Kong
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29
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Impact of sarA and Phenol-Soluble Modulins on the Pathogenesis of Osteomyelitis in Diverse Clinical Isolates of Staphylococcus aureus. Infect Immun 2016; 84:2586-94. [PMID: 27354444 DOI: 10.1128/iai.00152-16] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/18/2016] [Indexed: 12/21/2022] Open
Abstract
We used a murine model of acute, posttraumatic osteomyelitis to evaluate the virulence of two divergent Staphylococcus aureus clinical isolates (the USA300 strain LAC and the USA200 strain UAMS-1) and their isogenic sarA mutants. The results confirmed that both strains caused comparable degrees of osteolysis and reactive new bone formation in the acute phase of osteomyelitis. Conditioned medium (CM) from stationary-phase cultures of both strains was cytotoxic to cells of established cell lines (MC3TC-E1 and RAW 264.7 cells), primary murine calvarial osteoblasts, and bone marrow-derived osteoclasts. Both the cytotoxicity of CM and the reactive changes in bone were significantly reduced in the isogenic sarA mutants. These results confirm that sarA is required for the production and/or accumulation of extracellular virulence factors that limit osteoblast and osteoclast viability and that thereby promote bone destruction and reactive bone formation during the acute phase of S. aureus osteomyelitis. Proteomic analysis confirmed the reduced accumulation of multiple extracellular proteins in the LAC and UAMS-1 sarA mutants. Included among these were the alpha class of phenol-soluble modulins (PSMs), which were previously implicated as important determinants of osteoblast cytotoxicity and bone destruction and repair processes in osteomyelitis. Mutation of the corresponding operon reduced the cytotoxicity of CM from both UAMS-1 and LAC cultures for osteoblasts and osteoclasts. It also significantly reduced both reactive bone formation and cortical bone destruction by CM from LAC cultures. However, this was not true for CM from cultures of a UAMS-1 psmα mutant, thereby suggesting the involvement of additional virulence factors in such strains that remain to be identified.
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30
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Bronesky D, Wu Z, Marzi S, Walter P, Geissmann T, Moreau K, Vandenesch F, Caldelari I, Romby P. Staphylococcus aureus RNAIII and Its Regulon Link Quorum Sensing, Stress Responses, Metabolic Adaptation, and Regulation of Virulence Gene Expression. Annu Rev Microbiol 2016; 70:299-316. [PMID: 27482744 DOI: 10.1146/annurev-micro-102215-095708] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Staphylococcus aureus RNAIII is one of the main intracellular effectors of the quorum-sensing system. It is a multifunctional RNA that encodes a small peptide, and its noncoding parts act as antisense RNAs to regulate the translation and/or the stability of mRNAs encoding transcriptional regulators, major virulence factors, and cell wall metabolism enzymes. In this review, we explain how regulatory proteins and RNAIII are embedded in complex regulatory circuits to express virulence factors in a dynamic and timely manner in response to stress and environmental and metabolic changes.
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Affiliation(s)
- Delphine Bronesky
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
| | - Zongfu Wu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Stefano Marzi
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
| | - Philippe Walter
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
| | - Thomas Geissmann
- Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, Université de Lyon, INSERM U1111, CNRS UMR 5308, CIRI, 69008 Lyon, France
| | - Karen Moreau
- Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, Université de Lyon, INSERM U1111, CNRS UMR 5308, CIRI, 69008 Lyon, France
| | - François Vandenesch
- Université Claude Bernard Lyon 1, Ecole Normale Supérieure de Lyon, Université de Lyon, INSERM U1111, CNRS UMR 5308, CIRI, 69008 Lyon, France
| | - Isabelle Caldelari
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
| | - Pascale Romby
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 67084 Strasbourg, France;
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31
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Yajjala VK, Thomas VC, Bauer C, Scherr TD, Fischer KJ, Fey PD, Bayles KW, Kielian T, Sun K. Resistance to Acute Macrophage Killing Promotes Airway Fitness of Prevalent Community-Acquired Staphylococcus aureus Strains. THE JOURNAL OF IMMUNOLOGY 2016; 196:4196-203. [PMID: 27053759 DOI: 10.4049/jimmunol.1600081] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 03/13/2016] [Indexed: 11/19/2022]
Abstract
The incidence of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in otherwise healthy individuals is increasing. To investigate the mechanism underlying the epidemiological success of predominant community-associated (CA)-MRSA strains, we examined their fitness traits during the initial interaction between bacteria and the host occurring in the lower airway. Using a mouse respiratory infection model, we show that clinical isolates often responsible for CA infections are highly resistant to clearance from healthy airways, whereas S. aureus strains not as prevalent or traditionally associated with hospital-associated infections are relatively susceptible. Mechanistically, the competitive fitness of S. aureus is a result of both agr-dependent and -independent resistance to innate bacterial killing. Furthermore, we show that rather than evasion from neutrophil-dependent bactericidal process, the observed S. aureus fitness in the lower airways is due to its intrinsic resistance to resident alveolar macrophage-mediated intracellular killing. Importantly, we demonstrate that the virulence determinants responsible for bacterial persistence in immune-competent mice are dispensable in mice with predisposing conditions such as influenza infection. Taken together, these novel findings of the improved competence of predominant CA-MRSA strains to survive innate killing in healthy hosts, particularly at the very beginning stage of infection, provide a unique insight into their epidemiological success.
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Affiliation(s)
- Vijaya Kumar Yajjala
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Vinai Chittezham Thomas
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Christopher Bauer
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Tyler D Scherr
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Karl J Fischer
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Paul D Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Kenneth W Bayles
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Tammy Kielian
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Keer Sun
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
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32
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XerC Contributes to Diverse Forms of Staphylococcus aureus Infection via agr-Dependent and agr-Independent Pathways. Infect Immun 2016; 84:1214-1225. [PMID: 26857575 DOI: 10.1128/iai.01462-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 02/02/2016] [Indexed: 02/06/2023] Open
Abstract
We demonstrate that mutation of xerC, which reportedly encodes a homologue of an Escherichia coli recombinase, limits biofilm formation in the methicillin-resistant Staphylococcus aureus strain LAC and the methicillin-sensitive strain UAMS-1. This was not due to the decreased production of the polysaccharide intracellular adhesin (PIA) in either strain because the amount of PIA was increased in a UAMS-1xerC mutant and undetectable in both LAC and its isogenic xerC mutant. Mutation of xerC also resulted in the increased production of extracellular proteases and nucleases in both LAC and UAMS-1, and limiting the production of either class of enzymes increased biofilm formation in the isogenic xerC mutants. More importantly, the limited capacity to form a biofilm was correlated with increased antibiotic susceptibility in both strains in the context of an established biofilm in vivo. Mutation of xerC also attenuated virulence in a murine bacteremia model, as assessed on the basis of the bacterial loads in internal organs and overall lethality. It also resulted in the decreased accumulation of alpha toxin and the increased accumulation of protein A. These findings suggest that xerC may impact the functional status of agr. This was confirmed by demonstrating the reduced accumulation of RNAIII and AgrA in LAC and UAMS-1xerC mutants. However, this cannot account for the biofilm-deficient phenotype of xerC mutants because mutation of agr did not limit biofilm formation in either strain. These results demonstrate that xerC contributes to biofilm-associated infections and acute bacteremia and that this is likely due to agr-independent and -dependent pathways, respectively.
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Atwood DN, Beenken KE, Lantz TL, Meeker DG, Lynn WB, Mills WB, Spencer HJ, Smeltzer MS. Regulatory Mutations Impacting Antibiotic Susceptibility in an Established Staphylococcus aureus Biofilm. Antimicrob Agents Chemother 2016; 60:1826-9. [PMID: 26824954 PMCID: PMC4775981 DOI: 10.1128/aac.02750-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 12/26/2015] [Indexed: 02/04/2023] Open
Abstract
We previously determined the extent to which mutations of different Staphylococcus aureus regulatory loci impact biofilm formation as assessed under in vitro conditions. Here we extend these studies to determine the extent to which those regulatory loci that had the greatest effect on biofilm formation also impact antibiotic susceptibility. The experiments were done under in vitro and in vivo conditions using two clinical isolates of S. aureus (LAC and UAMS-1) and two functionally diverse antibiotics (daptomycin and ceftaroline). Mutation of the staphylococcal accessory regulator (sarA) or sigB was found to significantly increase susceptibilities to both antibiotics and in both strains in a manner that could not be explained by changes in the MICs. The impact of a mutation in sarA was comparable to that of a mutation in sigB and greater than the impact observed with any other mutant. These results suggest that therapeutic strategies targeting sarA and/or sigB have the greatest potential to facilitate the ability to overcome the intrinsic antibiotic resistance that defines S. aureus biofilm-associated infections.
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Affiliation(s)
- Danielle N Atwood
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Karen E Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Tamara L Lantz
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Daniel G Meeker
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - William B Lynn
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Weston B Mills
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Horace J Spencer
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Mark S Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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den Reijer PM, Haisma EM, Lemmens-den Toom NA, Willemse J, Koning RA, Demmers JAA, Dekkers DHW, Rijkers E, El Ghalbzouri A, Nibbering PH, van Wamel W. Detection of Alpha-Toxin and Other Virulence Factors in Biofilms of Staphylococcus aureus on Polystyrene and a Human Epidermal Model. PLoS One 2016; 11:e0145722. [PMID: 26741798 PMCID: PMC4704740 DOI: 10.1371/journal.pone.0145722] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/07/2015] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND & AIM The ability of Staphylococcus aureus to successfully colonize (a)biotic surfaces may be explained by biofilm formation and the actions of virulence factors. The aim of the present study was to establish the presence of 52 proteins, including virulence factors such as alpha-toxin, during biofilm formation of five different (methicillin resistant) S. aureus strains on Leiden human epidermal models (LEMs) and polystyrene surfaces (PS) using a competitive Luminex-based assay. RESULTS All five S. aureus strains formed biofilms on PS, whereas only three out of five strains formed biofilms on LEMs. Out of the 52 tested proteins, six functionally diverse proteins (ClfB, glucosaminidase, IsdA, IsaA, SACOL0688 and nuclease) were detected in biofilms of all strains on both PS and LEMs. At the same time, four toxins (alpha-toxin, gamma-hemolysin B and leukocidins D and E), two immune modulators (formyl peptide receptor-like inhibitory protein and Staphylococcal superantigen-like protein 1), and two other proteins (lipase and LytM) were detectable in biofilms by all five S. aureus strains on LEMs, but not on PS. In contrast, fibronectin-binding protein B (FnbpB) was detectable in biofilms by all S. aureus biofilms on PS, but not on LEMs. These data were largely confirmed by the results from proteomic and transcriptomic analyses and in case of alpha-toxin additionally by GFP-reporter technology. CONCLUSION Functionally diverse virulence factors of (methicillin-resistant) S. aureus are present during biofilm formation on LEMs and PS. These results could aid in identifying novel targets for future treatment strategies against biofilm-associated infections.
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Affiliation(s)
- P. M. den Reijer
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands
- * E-mail:
| | - E. M. Haisma
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | - N. A. Lemmens-den Toom
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - J. Willemse
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - R. A. Koning
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - J. A. A. Demmers
- Proteomics Centre, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - D. H. W. Dekkers
- Proteomics Centre, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - E. Rijkers
- Proteomics Centre, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - A. El Ghalbzouri
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | - P. H. Nibbering
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - W. van Wamel
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands
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Tranchemontagne ZR, Camire RB, O'Donnell VJ, Baugh J, Burkholder KM. Staphylococcus aureus Strain USA300 Perturbs Acquisition of Lysosomal Enzymes and Requires Phagosomal Acidification for Survival inside Macrophages. Infect Immun 2016; 84:241-53. [PMID: 26502911 PMCID: PMC4694005 DOI: 10.1128/iai.00704-15] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 10/22/2015] [Indexed: 02/08/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) causes invasive, drug-resistant skin and soft tissue infections. Reports that S. aureus bacteria survive inside macrophages suggest that the intramacrophage environment may be a niche for persistent infection; however, mechanisms by which the bacteria might evade macrophage phagosomal defenses are unclear. We examined the fate of the S. aureus-containing phagosome in THP-1 macrophages by evaluating bacterial intracellular survival and phagosomal acidification and maturation and by testing the impact of phagosomal conditions on bacterial viability. Multiple strains of S. aureus survived inside macrophages, and in studies using the MRSA USA300 clone, the USA300-containing phagosome acidified rapidly and acquired the late endosome and lysosome protein LAMP1. However, fewer phagosomes containing live USA300 bacteria than those containing dead bacteria associated with the lysosomal hydrolases cathepsin D and β-glucuronidase. Inhibiting lysosomal hydrolase activity had no impact on intracellular survival of USA300 or other S. aureus strains, suggesting that S. aureus perturbs acquisition of lysosomal enzymes. We examined the impact of acidification on S. aureus intramacrophage viability and found that inhibitors of phagosomal acidification significantly impaired USA300 intracellular survival. Inhibition of macrophage phagosomal acidification resulted in a 30-fold reduction in USA300 expression of the staphylococcal virulence regulator agr but had little effect on expression of sarA, saeR, or sigB. Bacterial exposure to acidic pH in vitro increased agr expression. Together, these results suggest that S. aureus survives inside macrophages by perturbing normal phagolysosome formation and that USA300 may sense phagosomal conditions and upregulate expression of a key virulence regulator that enables its intracellular survival.
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Affiliation(s)
| | - Ryan B Camire
- Department of Nursing, University of New England, Biddeford, Maine, USA
| | | | - Jessfor Baugh
- Department of Biology, University of New England, Biddeford, Maine, USA
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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: 3.2] [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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Tuchscherr L, Bischoff M, Lattar SM, Noto Llana M, Pförtner H, Niemann S, Geraci J, Van de Vyver H, Fraunholz MJ, Cheung AL, Herrmann M, Völker U, Sordelli DO, Peters G, Löffler B. Sigma Factor SigB Is Crucial to Mediate Staphylococcus aureus Adaptation during Chronic Infections. PLoS Pathog 2015; 11:e1004870. [PMID: 25923704 PMCID: PMC4414502 DOI: 10.1371/journal.ppat.1004870] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 04/09/2015] [Indexed: 12/26/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen that causes a range of infections from acute invasive to chronic and difficult-to-treat. Infection strategies associated with persisting S. aureus infections are bacterial host cell invasion and the bacterial ability to dynamically change phenotypes from the aggressive wild-type to small colony variants (SCVs), which are adapted for intracellular long-term persistence. The underlying mechanisms of the bacterial switching and adaptation mechanisms appear to be very dynamic, but are largely unknown. Here, we analyzed the role and the crosstalk of the global S. aureus regulators agr, sarA and SigB by generating single, double and triple mutants, and testing them with proteome analysis and in different in vitro and in vivo infection models. We were able to demonstrate that SigB is the crucial factor for adaptation in chronic infections. During acute infection, the bacteria require the simultaneous action of the agr and sarA loci to defend against invading immune cells by causing inflammation and cytotoxicity and to escape from phagosomes in their host cells that enable them to settle an infection at high bacterial density. To persist intracellularly the bacteria subsequently need to silence agr and sarA. Indeed agr and sarA deletion mutants expressed a much lower number of virulence factors and could persist at high numbers intracellularly. SigB plays a crucial function to promote bacterial intracellular persistence. In fact, ΔsigB-mutants did not generate SCVs and were completely cleared by the host cells within a few days. In this study we identified SigB as an essential factor that enables the bacteria to switch from the highly aggressive phenotype that settles an acute infection to a silent SCV-phenotype that allows for long-term intracellular persistence. Consequently, the SigB-operon represents a possible target to develop preventive and therapeutic strategies against chronic and therapy-refractory infections.
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Affiliation(s)
- Lorena Tuchscherr
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
| | - Markus Bischoff
- Institute of Medical Microbiology and Hygiene, University of Saarland Medical Center, Homburg, Germany
| | - Santiago M. Lattar
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Mariangeles Noto Llana
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Henrike Pförtner
- Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Silke Niemann
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Jennifer Geraci
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
| | - Hélène Van de Vyver
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Martin J. Fraunholz
- Department of Microbiology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Ambrose L. Cheung
- Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Mathias Herrmann
- Institute of Medical Microbiology and Hygiene, University of Saarland Medical Center, Homburg, Germany
| | - Uwe Völker
- Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Daniel O. Sordelli
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Georg Peters
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Bettina Löffler
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
- * E-mail:
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38
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Atwood DN, Loughran AJ, Courtney AP, Anthony AC, Meeker DG, Spencer HJ, Gupta RK, Lee CY, Beenken KE, Smeltzer MS. Comparative impact of diverse regulatory loci on Staphylococcus aureus biofilm formation. Microbiologyopen 2015; 4:436-51. [PMID: 25810138 PMCID: PMC4475386 DOI: 10.1002/mbo3.250] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 02/06/2015] [Indexed: 01/01/2023] Open
Abstract
The relative impact of 23 mutations on biofilm formation was evaluated in the USA300, methicillin-resistant strain LAC. Mutation of sarA, atl, codY, rsbU, and sigB limited biofilm formation in comparison to the parent strain, but the limitation imposed by mutation of sarA was greater than that imposed by mutation of any of these other genes. The reduced biofilm formation of all mutants other than the atl mutant was correlated with increased levels of extracellular proteases. Mutation of fur- and mgrA-enhanced biofilm formation but in LAC had no impact on protease activity, nuclease activity, or accumulation of the polysaccharide intercellular adhesin (PIA). The increased capacity of these mutants to form a biofilm was reversed by mutation of sarA, and this was correlated with increased protease production. Mutation of sarA, mgrA, and sigB had the same phenotypic effect in the methicillin-sensitive strain UAMS-1, but mutation of codY increased rather than decreased biofilm formation. As with the UAMS-1 mgrA mutant, this was correlated with increased production of PIA. Examination of four additional clinical isolates suggests that the differential impact of codY on biofilm formation may be a conserved characteristic of methicillin-resistant versus methicillin-sensitive strains.
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Affiliation(s)
- Danielle N Atwood
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Allister J Loughran
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Ashleah P Courtney
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Allison C Anthony
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Daniel G Meeker
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Horace J Spencer
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Ravi Kr Gupta
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Chia Y Lee
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Karen E Beenken
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Mark S Smeltzer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.,Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas.,Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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Stulik L, Malafa S, Hudcova J, Rouha H, Henics BZ, Craven DE, Sonnevend AM, Nagy E. α-Hemolysin activity of methicillin-susceptible Staphylococcus aureus predicts ventilator-associated pneumonia. Am J Respir Crit Care Med 2015; 190:1139-48. [PMID: 25303310 DOI: 10.1164/rccm.201406-1012oc] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Colonization of lower airways by Staphylococcus aureus is a risk factor for the development of ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). However, little is known about the virulence factors of methicillin-sensitive and -resistant S. aureus (MSSA and MRSA) that may influence host colonization and progression to VAT and VAP. OBJECTIVES We evaluated MRSA and MSSA endotracheal aspirates (ETA) for genotype and α-hemolysin activity in relation to the development of VAT and VAP. METHODS Serial S. aureus ETA isolates from ventilated patients were analyzed for methicillin resistance, molecular type by Multi-Locus Sequence Typing and spa-typing, and α-hemolysin activity by semiquantitative analysis of hemolysis on sheep blood agar and quantitative measurement of cytolysis of human lung epithelial cells. The virulence of selected strains was assessed in mice by intranasal challenge. MEASUREMENTS AND MAIN RESULTS We detected S. aureus from ETA samples in a quarter of the 231 ventilated patients analyzed; one-third of them developed VAP. VAP patients (n = 15) were mainly infected by MSSA strains (87%), whereas colonized individuals (n = 18) not progressing to disease mainly carried MRSA strains (68%). MSSA isolates from colonized or VAT patients exhibited significantly lower α-hemolysin activity than those from VAP cases; however, no such relationship was found with MRSA strains. α-Hemolysin activity of S. aureus isolates was predictive for virulence in mouse pneumonia model. CONCLUSIONS MSSA strains with strong blood agar hemolysis and high α-hemolysin activity are markers for VAP, but not VAT, and might be considered in differential diagnosis and initiation of therapy.
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40
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Mootz JM, Benson MA, Heim CE, Crosby HA, Kavanaugh JS, Dunman PM, Kielian T, Torres VJ, Horswill AR. Rot is a key regulator of Staphylococcus aureus biofilm formation. Mol Microbiol 2015; 96:388-404. [PMID: 25612137 DOI: 10.1111/mmi.12943] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2015] [Indexed: 01/28/2023]
Abstract
Staphylococcus aureus is a significant cause of chronic biofilm infections on medical implants. We investigated the biofilm regulatory cascade and discovered that the repressor of toxins (Rot) is part of this pathway. A USA300 community-associated methicillin-resistant S. aureus strain deficient in Rot was unable to form a biofilm using multiple different assays, and we found rot mutants in other strain lineages were also biofilm deficient. By performing a global analysis of transcripts and protein production controlled by Rot, we observed that all the secreted protease genes were up-regulated in a rot mutant, and we hypothesized that this regulation could be responsible for the biofilm phenotype. To investigate this question, we determined that Rot bound to the protease promoters, and we observed that activity levels of these enzymes, in particular the cysteine proteases, were increased in a rot mutant. By inactivating these proteases, biofilm capacity was restored to the mutant, demonstrating they are responsible for the biofilm negative phenotype. Finally, we tested the rot mutant in a mouse catheter model of biofilm infection and observed a significant reduction in biofilm burden. Thus S. aureus uses the transcription factor Rot to repress secreted protease levels in order to build a biofilm.
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Affiliation(s)
- Joe M Mootz
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
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41
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Loughran AJ, Atwood DN, Anthony AC, Harik NS, Spencer HJ, Beenken KE, Smeltzer MS. Impact of individual extracellular proteases on Staphylococcus aureus biofilm formation in diverse clinical isolates and their isogenic sarA mutants. Microbiologyopen 2014; 3:897-909. [PMID: 25257373 PMCID: PMC4263513 DOI: 10.1002/mbo3.214] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 08/07/2014] [Accepted: 08/15/2014] [Indexed: 01/01/2023] Open
Abstract
We demonstrate that the purified Staphylococcus aureus extracellular proteases aureolysin, ScpA, SspA, and SspB limit biofilm formation, with aureolysin having the greatest impact. Using protease-deficient derivatives of LAC, we confirmed that this is due to the individual proteases themselves. Purified aureolysin, and to a lesser extent ScpA and SspB, also promoted dispersal of an established biofilm. Mutation of the genes encoding these proteases also only partially restored biofilm formation in an FPR3757 sarA mutant and had little impact on restoring virulence in a murine bacteremia model. In contrast, eliminating the production of all of these proteases fully restored both biofilm formation and virulence in a sarA mutant generated in the closely related USA300 strain LAC. These results confirm an important role for multiple extracellular proteases in S. aureus pathogenesis and the importance of sarA in repressing their production. Moreover, purified aureolysin limited biofilm formation in 14 of 15 methicillin-resistant isolates and 11 of 15 methicillin-susceptible isolates, while dispersin B had little impact in UAMS-1, LAC, or 29 of 30 contemporary isolates of S. aureus. This suggests that the role of sarA and its impact on protease production is important in diverse strains of S. aureus irrespective of their methicillin resistance status.
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Affiliation(s)
- Allister J Loughran
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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42
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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: 2.6] [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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43
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The msaABCR operon regulates resistance in vancomycin-intermediate Staphylococcus aureus strains. Antimicrob Agents Chemother 2014; 58:6685-95. [PMID: 25155591 DOI: 10.1128/aac.03280-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vancomycin-intermediate Staphylococcus aureus (VISA) strains present an increasingly difficult problem in terms of public health. However, the molecular mechanism for this resistance is not yet understood. In this study, we define the role of the msaABCR operon in vancomycin resistance in three clinical VISA strains, i.e., Mu50, HIP6297, and LIM2. Deletion of the msaABCR operon resulted in significant decreases in the vancomycin MIC (from 6.25 to 1.56 μg/ml) and significant reductions of cell wall thickness in strains Mu50 and HIP6297. Growth of the mutants in medium containing vancomycin at concentrations greater than 2 μg/ml resulted in decreases in the growth rate, compared with the wild-type strains. Mutation of the msaABCR operon also reduced the binding capacity for vancomycin. We conclude that the msaABCR operon contributes to resistance to vancomycin and cell wall synthesis in S. aureus.
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Tavares A, Nielsen JB, Boye K, Rohde S, Paulo AC, Westh H, Schønning K, de Lencastre H, Miragaia M. Insights into alpha-hemolysin (Hla) evolution and expression among Staphylococcus aureus clones with hospital and community origin. PLoS One 2014; 9:e98634. [PMID: 25033196 PMCID: PMC4102472 DOI: 10.1371/journal.pone.0098634] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/06/2014] [Indexed: 01/09/2023] Open
Abstract
Background Alpha-hemolysin (Hla) is a major virulence factor in the pathogenesis of Staphylococcus aureus infection, being active against a wide range of host cells. Although hla is ubiquitous in S. aureus, its genetic diversity and variation in expression in different genetic backgrounds is not known. We evaluated nucleotide sequence variation and gene expression profiles of hla among representatives of hospital (HA) and community-associated (CA) S. aureus clones. Methods 51 methicillin-resistant S. aureus and 22 methicillin-susceptible S. aureus were characterized by PFGE, spa typing, MLST and SCCmec typing. The internal regions of hla and the hla promoter were sequenced and gene expression was assessed by RT-PCR. Results Alpha-hemolysin encoding- and promoter sequences were diverse, with 12 and 23 different alleles, respectively. Based on phylogenetic analysis, we suggest that hla may have evolved together with the S. aureus genetic background, except for ST22, ST121, ST59 and ST93. Conversely, the promoter region showed lack of co-evolution with the genetic backgrounds. Four non-synonymous amino acid changes were identified close to important regions of hla activity. Amino acid changes in the RNAIII binding site were not associated to hla expression. Although expression rates of hla were in general strain-specific, we observed CA clones showed significantly higher hla expression (p = 0.003) when compared with HA clones. Conclusion We propose that the hla gene has evolved together with the genetic background. Overall, CA genetic backgrounds showed higher levels of hla expression than HA, and a high strain-to-strain variation of gene expression was detected in closely related strains.
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Affiliation(s)
- Ana Tavares
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica (ITQB), Oeiras, Portugal
| | - Jesper B. Nielsen
- Dept. of Clinical Microbiology 445, Copenhagen University Hospital, Hvidovre, Denmark
| | - Kit Boye
- Dept. of Clinical Microbiology 445, Copenhagen University Hospital, Hvidovre, Denmark
| | - Susanne Rohde
- Dept. of Clinical Microbiology 445, Copenhagen University Hospital, Hvidovre, Denmark
| | - Ana C. Paulo
- Molecular Microbiology of Human Pathogens, ITQB, Oeiras, Portugal
| | - Henrik Westh
- Dept. of Clinical Microbiology 445, Copenhagen University Hospital, Hvidovre, Denmark
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Schønning
- Dept. of Clinical Microbiology 445, Copenhagen University Hospital, Hvidovre, Denmark
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hermínia de Lencastre
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica (ITQB), Oeiras, Portugal
- Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, New York, United States of America
| | - Maria Miragaia
- Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica (ITQB), Oeiras, Portugal
- Laboratory of Bacterial Evolution and Molecular Epidemiology, ITQB, Oeiras, Portugal
- * E-mail:
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45
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Yoong P, Torres VJ. Animal models and imaging technologies: paving the way towards insights into Staphylococcus aureus-induced osteomyelitis. Future Microbiol 2014; 8:1515-8. [PMID: 24266351 DOI: 10.2217/fmb.13.136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Pauline Yoong
- Department of Microbiology, Microbial Pathogenesis Program, Smilow Research Building, Room 1010, New York University School of Medicine, 522 First Avenue, NY 10016, USA
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46
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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: 22] [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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Stella NA, Shanks RMQ. Cyclic-AMP inhibition of fimbriae and prodigiosin production by Serratia marcescens is strain-dependent. Arch Microbiol 2014; 196:323-30. [PMID: 24619531 DOI: 10.1007/s00203-014-0970-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 02/07/2014] [Accepted: 02/24/2014] [Indexed: 12/26/2022]
Abstract
The cyclic-nucleotide 3',5'-cyclic AMP (cAMP) is an ancient and widespread regulatory molecule. Previous studies have shown that fimbria production and secondary metabolite production are inhibited by cAMP in the prokaryote Serratia marcescens. This study used genetic manipulations to test the strain specificity of cAMP-cyclic-AMP receptor protein regulation of fimbria production and of the red pigment, prodigiosin. A surprising amount of variation was observed, as multicopy expression of the cAMP-phosphodiesterase gene, cpdS, conferred either an increase or decrease in fimbriae-dependent yeast agglutination and prodigiosin production depending upon the strain background. Mutation of crp, the gene coding for the cAMP-receptor protein, similarly conferred strain-dependent phenotypes. This study shows that three distinct biological properties, modulated by a conserved genetic regulatory molecule, can vary significantly among strains. Such variation can complicate the functional analysis of bacterial phenotypic properties which are dependent upon global genetic regulators such as cAMP.
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Affiliation(s)
- Nicholas A Stella
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, 15213, USA,
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48
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Identification of the Staphylococcus aureus vfrAB operon, a novel virulence factor regulatory locus. Infect Immun 2014; 82:1813-22. [PMID: 24549328 DOI: 10.1128/iai.01655-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
During a screen of the Nebraska Transposon Mutant Library, we identified 71 mutations in the Staphylococcus aureus genome that altered hemolysis on blood agar medium. Although many of these mutations disrupted genes known to affect the production of alpha-hemolysin, two of them were associated with an apparent operon, designated vfrAB, that had not been characterized previously. Interestingly, a ΔvfrB mutant exhibited only minor effects on the transcription of the hla gene, encoding alpha-hemolysin, when grown in broth, as well as on RNAIII, a posttranscriptional regulatory RNA important for alpha-hemolysin translation, suggesting that VfrB may function at the posttranscriptional level. Indeed, a ΔvfrB mutant had increased aur and sspAB protease expression under these conditions. However, disruption of the known secreted proteases in the ΔvfrB mutant did not restore hemolytic activity in the ΔvfrB mutant on blood agar. Further analysis revealed that, in contrast to the minor effects of VfrB on hla transcription when strains were cultured in liquid media, the level of hla transcription was decreased 50-fold in the absence of VfrB on solid media. These results demonstrate that while VfrB represses protease expression when strains are grown in broth, hla regulation is highly responsive to factors associated with growth on solid media. Intriguingly, the ΔvfrB mutant displayed increased pathogenesis in a model of S. aureus dermonecrosis, further highlighting the complexity of VfrB-dependent virulence regulation. The results of this study describe a phenotype associated with a class of highly conserved yet uncharacterized proteins found in Gram-positive bacteria, and they shed new light on the regulation of virulence factors necessary for S. aureus pathogenesis.
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49
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Cheung GYC, Joo HS, Chatterjee SS, Otto M. Phenol-soluble modulins--critical determinants of staphylococcal virulence. FEMS Microbiol Rev 2014; 38:698-719. [PMID: 24372362 DOI: 10.1111/1574-6976.12057] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 12/05/2013] [Accepted: 12/19/2013] [Indexed: 10/25/2022] Open
Abstract
Phenol-soluble modulins (PSMs) are a recently discovered family of amphipathic, alpha-helical peptides that have multiple roles in staphylococcal pathogenesis and contribute to a large extent to the pathogenic success of virulent staphylococci, such as Staphylococcus aureus. PSMs may cause lysis of many human cell types including leukocytes and erythrocytes, stimulate inflammatory responses, and contribute to biofilm development. PSMs appear to have an original role in the commensal lifestyle of staphylococci, where they facilitate growth and spreading on epithelial surfaces. Aggressive, cytolytic PSMs seem to have evolved from that original role and are mainly expressed in highly virulent S. aureus. Here, we will review the biochemistry, genetics, and role of PSMs in the commensal and pathogenic lifestyles of staphylococci, discuss how diversification of PSMs defines the aggressiveness of staphylococcal species, and evaluate potential avenues to target PSMs for drug development against staphylococcal infections.
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Affiliation(s)
- Gordon Y C Cheung
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, MD, USA
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50
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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: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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