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Hossain A, Gnanagobal H, Cao T, Chakraborty S, Chukwu-Osazuwa J, Soto-Dávila M, Vasquez I, Santander J. Role of cold shock proteins B and D in Aeromonas salmonicida subsp. salmonicida physiology and virulence in lumpfish ( Cyclopterus lumpus). Infect Immun 2024; 92:e0001124. [PMID: 38920386 PMCID: PMC11320987 DOI: 10.1128/iai.00011-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 06/05/2024] [Indexed: 06/27/2024] Open
Abstract
Cold shock proteins (Csp) are pivotal nucleic acid binding proteins known for their crucial roles in the physiology and virulence of various bacterial pathogens affecting plant, insect, and mammalian hosts. However, their significance in bacterial pathogens of teleost fish remains unexplored. Aeromonas salmonicida subsp. salmonicida (hereafter A. salmonicida) is a psychrotrophic pathogen and the causative agent of furunculosis in marine and freshwater fish. Four csp genes (cspB, cspD, cspA, and cspC) have been identified in the genome of A. salmonicida J223 (wild type). Here, we evaluated the role of DNA binding proteins, CspB and CspD, in A. salmonicida physiology and virulence in lumpfish (Cyclopterus lumpus). A. salmonicida ΔcspB, ΔcspD, and the double ΔcspBΔcspD mutants were constructed and characterized. A. salmonicida ΔcspB and ΔcspBΔcspD mutants showed a faster growth at 28°C, and reduced virulence in lumpfish. A. salmonicida ΔcspD showed a slower growth at 28°C, biofilm formation, lower survival in low temperatures and freezing conditions (-20°C, 0°C, and 4°C), deficient in lipopolysaccharide synthesis, and low virulence in lumpfish. Additionally, ΔcspBΔcspD mutants showed less survival in the presence of bile compared to the wild type. Transcriptome analysis revealed that 200, 37, and 921 genes were differentially expressed in ΔcspB, ΔcspD, and ΔcspBΔcspD, respectively. In ΔcspB and ΔcspBΔcspD virulence genes in the chromosome and virulence plasmid were downregulated. Our analysis indicates that CspB and CspD mostly act as a transcriptional activator, influencing cell division (e.g., treB), virulence factors (e.g., aexT), and ultimately virulence.
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Affiliation(s)
- Ahmed Hossain
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, Ocean Science Center, St. John's, Newfoundland, Canada
| | - Hajarooba Gnanagobal
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, Ocean Science Center, St. John's, Newfoundland, Canada
| | - Trung Cao
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, Ocean Science Center, St. John's, Newfoundland, Canada
| | - Setu Chakraborty
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, Ocean Science Center, St. John's, Newfoundland, Canada
| | - Joy Chukwu-Osazuwa
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, Ocean Science Center, St. John's, Newfoundland, Canada
| | - Manuel Soto-Dávila
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, Ocean Science Center, St. John's, Newfoundland, Canada
| | - Ignacio Vasquez
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, Ocean Science Center, St. John's, Newfoundland, Canada
| | - Javier Santander
- Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, Ocean Science Center, St. John's, Newfoundland, Canada
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Truong-Bolduc QC, Wang Y, Ferrer-Espada R, Reedy JL, Martens AT, Goulev Y, Paulsson J, Vyas JM, Hooper DC. Staphylococcus aureus AbcA transporter enhances persister formation under β-lactam exposure. Antimicrob Agents Chemother 2024; 68:e0134023. [PMID: 38364015 PMCID: PMC10916373 DOI: 10.1128/aac.01340-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/18/2024] [Indexed: 02/18/2024] Open
Abstract
We evaluated the role of Staphylococcus aureus AbcA transporter in bacterial persistence and survival following exposure to the bactericidal agents nafcillin and oxacillin at both the population and single-cell levels. We show that AbcA overexpression resulted in resistance to nafcillin but not oxacillin. Using distinct fluorescent reporters of cell viability and AbcA expression, we found that over 6-14 hours of persistence formation, the proportion of AbcA reporter-expressing cells assessed by confocal microscopy increased sixfold as cell viability reporters decreased. Similarly, single-cell analysis in a high-throughput microfluidic system found a strong correspondence between antibiotic exposure and AbcA reporter expression. Persister cells grown in the absence of antibiotics showed neither an increase in nafcillin MIC nor in abcA transcript levels, indicating that survival was not associated with stable mutational resistance or abcA overexpression. Furthermore, persister cell levels on exposure to 1×MIC and 25×MIC of nafcillin decreased in an abcA knockout mutant. Survivors of nafcillin and oxacillin treatment overexpressed transporter AbcA, contributing to an enrichment of the number of persisters during treatment with pump-substrate nafcillin but not with pump-non-substrate oxacillin, indicating that efflux pump expression can contribute selectively to the survival of a persister population.
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Affiliation(s)
- Q. C. Truong-Bolduc
- Infectious Diseases Division and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Y. Wang
- Infectious Diseases Division and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - R. Ferrer-Espada
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - J. L. Reedy
- Infectious Diseases Division and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - A. T. Martens
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Y. Goulev
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - J. Paulsson
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - J. M. Vyas
- Infectious Diseases Division and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - D. C. Hooper
- Infectious Diseases Division and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Campbell MJ, Beenken KE, Spencer HJ, Jayana B, Hester H, Sahukhal GS, Elasri MO, Smeltzer MS. Comparative evaluation of small molecules reported to be inhibitors of Staphylococcus aureus biofilm formation. Microbiol Spectr 2024; 12:e0314723. [PMID: 38059629 PMCID: PMC10782960 DOI: 10.1128/spectrum.03147-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/09/2023] [Indexed: 12/08/2023] Open
Abstract
IMPORTANCE Because biofilm formation is such a problematic feature of Staphylococcus aureus infections, much effort has been put into identifying biofilm inhibitors. However, the results observed with these compounds are often reported in isolation, and the methods used to assess biofilm formation vary between labs, making it impossible to assess relative efficacy and prioritize among these putative inhibitors for further study. The studies we report address this issue by directly comparing putative biofilm inhibitors using a consistent in vitro assay. This assay was previously shown to maximize biofilm formation, and the results observed with this assay have been proven to be relevant in vivo. Of the 19 compounds compared using this method, many had no impact on biofilm formation under these conditions. Indeed, only one proved effective at limiting biofilm formation without also inhibiting growth.
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Affiliation(s)
- Mara J. Campbell
- 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
| | - Horace J. Spencer
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Bina Jayana
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Hana Hester
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Gyan S. Sahukhal
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Mohamed O. Elasri
- 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
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G C B, Sahukhal GS, Elasri MO. Delineating the Role of the msaABCR Operon in Staphylococcal Overflow Metabolism. Front Microbiol 2022; 13:914512. [PMID: 35722290 PMCID: PMC9204165 DOI: 10.3389/fmicb.2022.914512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus is an important human pathogen that can infect almost every organ system, resulting in a high incidence of morbidity and mortality. The msaABCR operon is an important regulator of several staphylococcal phenotypes, including biofilm development, cell wall crosslinking, antibiotic resistance, oxidative stress, and acute and chronic implant-associated osteomyelitis. Our previous study showed that, by modulating murein hydrolase activity, the msaABCR operon negatively regulates the proteases that govern cell death. Here, we report further elucidation of the mechanism of cell death, which is regulated by the msaABCR operon at the molecular level in the USA300 LAC strain. We showed that deletion of msaABCR enhances weak-acid-dependent cell death, because, in the biofilm microenvironment, this mutant strain consumes glucose and produces acetate and acetoin at higher rates than wild-type USA300 LAC strain. We proposed the increased intracellular acidification leads to increased cell death. MsaB, a dual-function transcription factor and RNA chaperone, is a negative regulator of the cidR regulon, which has been shown to play an important role in overflow metabolism and programmed cell death during biofilm development in S. aureus. We found that MsaB binds directly to the cidR promoter, which represses expression of the cidR regulon and prevents transcription of the cidABC and alsSD operons. In addition, we observed that pyruvate induced expression of the msaABCR operon (MsaB). The results reported here have enabled us to decipher the role of the msaABCR operon in staphylococcal metabolic adaption during biofilm development.
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Affiliation(s)
- Bibek G C
- Center for Molecular and Cellular Biosciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Gyan S. Sahukhal
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
- *Correspondence: Gyan S. Sahukhal,
| | - Mohamed O. Elasri
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
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Askoura M, Yousef N, Mansour B, Yehia FAZA. Antibiofilm and staphyloxanthin inhibitory potential of terbinafine against Staphylococcus aureus: in vitro and in vivo studies. Ann Clin Microbiol Antimicrob 2022; 21:21. [PMID: 35637481 PMCID: PMC9153124 DOI: 10.1186/s12941-022-00513-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 05/06/2022] [Indexed: 11/13/2022] Open
Abstract
Background Antimicrobial resistance is growing substantially, which necessitates the search for novel therapeutic options. Terbinafine, an allylamine antifungal agent that exhibits a broad spectrum of activity and is used in the treatment of dermatophytosis, could be a possible option to disarm S. aureus virulence. Methods Terbinafine inhibitory effect on staphyloxanthin was characterized by quantitative measurement of staphyloxanthin intermediates and molecular docking. The effect of terbinafine on S. aureus stress survival was characterized by viable counting. The anti-biofilm activity of terbinafine on S. aureus was assessed by the crystal violet assay and microscopy. Changes in S. aureus membrane following treatment with terbinafine were determined using Fourier transform infrared (FTIR) analysis. The synergistic action of terbinafine in combination with conventional antibiotics was characterized using the checkerboard assay. qRT-PCR was used to evaluate the impact of terbinafine on S. aureus gene expression. The influence of terbinafine on S. aureus pathogenesis was investigated in mice infection model. Results Terbinafine inhibits staphyloxanthin biosynthesis through targeting dehydrosqualene desaturase (CrtN). Docking analysis of terbinafine against the predicted active site of CrtN reveals a binding energy of − 9.579 kcal/mol exemplified by the formation of H-bonds, H-arene bonds, and hydrophobic/hydrophilic interactions with the conserved amino acids of the receptor pocket. Terbinafine treated S. aureus was more susceptible to both oxidative and acid stress as well as human blood killing as compared to untreated cells. Targeting staphyloxanthin by terbinafine rendered S. aureus more sensitive to membrane acting antibiotics. Terbinafine interfered with S. aureus biofilm formation through targeting cell autoaggregation, hydrophobicity, and exopolysaccharide production. Moreover, terbinafine demonstrated a synergistic interaction against S. aureus when combined with conventional antibiotics. Importantly, terbinafine attenuated S. aureus pathogenesis using mice infection model. qRT-PCR revealed that terbinafine repressed expression of the transcriptional regulators sigB, sarA, and msaB, as well as icaA in S. aureus. Conclusions Present findings strongly suggest that terbinafine could be used safely and efficiently as an anti-virulent agent to combat S. aureus infections.
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Affiliation(s)
- Momen Askoura
- Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt.
| | - Nehal Yousef
- Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt
| | - Basem Mansour
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Delta University for Science and Technology, Gamasa 11152, Belqas, Egypt
| | - Fatma Al-Zahraa A Yehia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt
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TMT proteomic analysis for molecular mechanism of Staphylococcus aureus in response to freezing stress. Appl Microbiol Biotechnol 2022; 106:3139-3152. [PMID: 35460349 DOI: 10.1007/s00253-022-11927-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/07/2022] [Accepted: 04/11/2022] [Indexed: 11/02/2022]
Abstract
The foodborne pathogen Staphylococcus aureus continues to challenge the food industry due to the pathogenicity and tolerance of the bacterium. As a common storage condition for frozen food during transportation, distribution, and storage, freezing does not seem to be entirely safe due to the cold tolerance of S. aureus. In addition, our study indicated that the biofilm formation ability of S. aureus was significantly increased in response to freezing stress. To explore the molecular mechanism regulating the response to freezing stress, the proteomics signature of S. aureus after freezing stress based on tandem mass tag (TMT) labeling and liquid chromatography tandem mass spectrometry (LC-MS/MS) was analyzed. Gene Ontology and pathway analysis revealed that ribosome function, metabolism, RNA repair, and stress response proteins were differentially regulated (P < 0.05). Furthermore, transpeptidase sortase A, biofilm operon icaADBC HTH-type negative transcriptional regulator IcaR, and HTH-type transcriptional regulator MgrA were involved in the modulation of increased biofilm formation in response to freezing stress (P < 0.05). Moreover, significant lysine acetylation and malonylation signals in the S. aureus response to freezing stress were observed. Collectively, the current work provides additional insight for comprehending the molecular mechanism of S. aureus in response to freezing stress and presents potential targets for developing strategies to control S. aureus. KEY POINTS: • TMT proteomic analysis was first used on S. aureus in response to freezing stress. • Ribosome-, metabolism-, and biofilm-related proteins change after freezing stress. • Increased biofilm formation in S. aureus responded to freezing stress.
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Celastrol mitigates staphyloxanthin biosynthesis and biofilm formation in Staphylococcus aureus via targeting key regulators of virulence; in vitro and in vivo approach. BMC Microbiol 2022; 22:106. [PMID: 35421933 PMCID: PMC9011992 DOI: 10.1186/s12866-022-02515-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/01/2022] [Indexed: 12/18/2022] Open
Abstract
Abstract
Background
Staphylococcus aureus is a leading cause of human infections. The spread of antibiotic-resistant staphylococci has driven the search for novel strategies to supersede antibiotics use. Thus, targeting bacterial virulence rather than viability could be a possible alternative.
Results
The influence of celastrol on staphyloxanthin (STX) biosynthesis, biofilm formation, antibiotic susceptibility and host pathogenesis in S. aureus has been investigated. Celastrol efficiently reduced STX biosynthesis in S. aureus. Liquid chromatography-mass spectrometry (LC–MS) and molecular docking revealed that celastrol inhibits STX biosynthesis through its effect on CrtM. Quantitative measurement of STX intermediates showed a significant pigment inhibition via interference of celastrol with CrtM and accumulation of its substrate, farnesyl diphosphate. Importantly, celastrol-treated S. aureus was more sensitive to environmental stresses and human blood killing than untreated bacteria. Similarly, inhibition of STX upon celastrol treatment rendered S. aureus more susceptible to membrane targeting antibiotics. In addition to its anti-pigment capability, celastrol exhibits significant anti-biofilm activity against S. aureus as indicated by crystal violet assay and microscopy. Celastrol-treated cells showed deficient exopolysaccharide production and cell hydrophobicity. Moreover, celastrol markedly synergized the action of conventional antibiotics against S. aureus and reduced bacterial pathogenesis in vivo using mice infection model. These findings were further validated using qRT-PCR, demonstrating that celastrol could alter the expression of STX biosynthesis genes as well as biofilm formation related genes and bacterial virulence.
Conclusions
Celastrol is a novel anti-virulent agent against S. aureus suggesting, a prospective therapeutic role for celastrol as a multi-targeted anti-pathogenic agent.
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Muchaamba F, Wambui J, Stephan R, Tasara T. Cold Shock Proteins Promote Nisin Tolerance in Listeria monocytogenes Through Modulation of Cell Envelope Modification Responses. Front Microbiol 2022; 12:811939. [PMID: 35003042 PMCID: PMC8740179 DOI: 10.3389/fmicb.2021.811939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 11/24/2021] [Indexed: 12/03/2022] Open
Abstract
Listeria monocytogenes continues to be a food safety challenge owing to its stress tolerance and virulence traits. Several listeriosis outbreaks have been linked to the consumption of contaminated ready-to-eat food products. Numerous interventions, including nisin application, are presently employed to mitigate against L. monocytogenes risk in food products. In response, L. monocytogenes deploys several defense mechanisms, reducing nisin efficacy, that are not yet fully understood. Cold shock proteins (Csps) are small, highly conserved nucleic acid-binding proteins involved in several gene regulatory processes to mediate various stress responses in bacteria. L. monocytogenes possesses three csp gene paralogs; cspA, cspB, and cspD. Using a panel of single, double, and triple csp gene deletion mutants, the role of Csps in L. monocytogenes nisin tolerance was examined, demonstrating their importance in nisin stress responses of this bacterium. Without csp genes, a L. monocytogenes ΔcspABD mutant displayed severely compromised growth under nisin stress. Characterizing single (ΔcspA, ΔcspB, and ΔcspD) and double (ΔcspBD, ΔcspAD, and ΔcspAB) csp gene deletion mutants revealed a hierarchy (cspD > cspB > cspA) of importance in csp gene contributions toward the L. monocytogenes nisin tolerance phenotype. Individual eliminations of either cspA or cspB improved the nisin stress tolerance phenotype, suggesting that their expression has a curbing effect on the expression of nisin resistance functions through CspD. Gene expression analysis revealed that Csp deficiency altered the expression of DltA, MprF, and penicillin-binding protein-encoding genes. Furthermore, the ΔcspABD mutation induced an overall more electronegative cell surface, enhancing sensitivity to nisin and other cationic antimicrobials as well as the quaternary ammonium compound disinfectant benzalkonium chloride. These observations demonstrate that the molecular functions of Csps regulate systems important for enabling the constitution and maintenance of an optimal composed cell envelope that protects against cell-envelope-targeting stressors, including nisin. Overall, our data show an important contribution of Csps for L. monocytogenes stress protection in food environments where antimicrobial peptides are used. Such knowledge can be harnessed in the development of better L. monocytogenes control strategies. Furthermore, the potential that Csps have in inducing cross-protection must be considered when combining hurdle techniques or using them in a series.
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Affiliation(s)
- Francis Muchaamba
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zürich, Zurich, Switzerland
| | - Joseph Wambui
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zürich, Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zürich, Zurich, Switzerland
| | - Taurai Tasara
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zürich, Zurich, Switzerland
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Listeria monocytogenes Cold Shock Proteins: Small Proteins with A Huge Impact. Microorganisms 2021; 9:microorganisms9051061. [PMID: 34068949 PMCID: PMC8155936 DOI: 10.3390/microorganisms9051061] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 01/26/2023] Open
Abstract
Listeria monocytogenes has evolved an extensive array of mechanisms for coping with stress and adapting to changing environmental conditions, ensuring its virulence phenotype expression. For this reason, L. monocytogenes has been identified as a significant food safety and public health concern. Among these adaptation systems are cold shock proteins (Csps), which facilitate rapid response to stress exposure. L. monocytogenes has three highly conserved csp genes, namely, cspA, cspB, and cspD. Using a series of csp deletion mutants, it has been shown that L. monocytogenes Csps are important for biofilm formation, motility, cold, osmotic, desiccation, and oxidative stress tolerance. Moreover, they are involved in overall virulence by impacting the expression of virulence-associated phenotypes, such as hemolysis and cell invasion. It is postulated that during stress exposure, Csps function to counteract harmful effects of stress, thereby preserving cell functions, such as DNA replication, transcription and translation, ensuring survival and growth of the cell. Interestingly, it seems that Csps might suppress tolerance to some stresses as their removal resulted in increased tolerance to stresses, such as desiccation for some strains. Differences in csp roles among strains from different genetic backgrounds are apparent for desiccation tolerance and biofilm production. Additionally, hierarchical trends for the different Csps and functional redundancies were observed on their influences on stress tolerance and virulence. Overall current data suggest that Csps have a wider role in bacteria physiology than previously assumed.
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Ray S, Da Costa R, Thakur S, Nandi D. Salmonella Typhimurium encoded cold shock protein E is essential for motility and biofilm formation. MICROBIOLOGY-SGM 2021; 166:460-473. [PMID: 32159509 DOI: 10.1099/mic.0.000900] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The ability of bacteria to form biofilms increases their survival under adverse environmental conditions. Biofilms have enormous medical and environmental impact; consequently, the factors that influence biofilm formation are an important area of study. In this investigation, the roles of two cold shock proteins (CSP) during biofilm formation were investigated in Salmonella Typhimurium, which is a major foodborne pathogen. Among all CSP transcripts studied, the expression of cspE (STM14_0732) was higher during biofilm growth. The cspE deletion strain (ΔcspE) did not form biofilms on a cholesterol coated glass surface; however, complementation with WT cspE, but not the F30V mutant, was able to rescue this phenotype. Transcript levels of other CSPs demonstrated up-regulation of cspA (STM14_4399) in ΔcspE. The cspA deletion strain (ΔcspA) did not affect biofilm formation; however, ΔcspEΔcspA exhibited higher biofilm formation compared to ΔcspE. Most likely, the higher cspA amounts in ΔcspE reduced biofilm formation, which was corroborated using cspA over-expression studies. Further functional studies revealed that ΔcspE and ΔcspEΔcspA exhibited slow swimming but no swarming motility. Although cspA over-expression did not affect motility, cspE complementation restored the swarming motility of ΔcspE. The transcript levels of the major genes involved in motility in ΔcspE demonstrated lower expression of the class III (fliC, motA, cheY), but not class I (flhD) or class II (fliA, fliL), flagellar regulon genes. Overall, this study has identified the interplay of two CSPs in regulating two biological processes: CspE is essential for motility in a CspA-independent manner whereas biofilm formation is CspA-dependent.
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Affiliation(s)
- Semanti Ray
- Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Rochelle Da Costa
- Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Samriddhi Thakur
- Department of Undergraduate Studies, Indian Insitute of Science, Bangalore-560012, India
| | - Dipankar Nandi
- Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
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11
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Pandey S, Sahukhal GS, Elasri MO. The msaABCR Operon Regulates Persister Formation by Modulating Energy Metabolism in Staphylococcus aureus. Front Microbiol 2021; 12:657753. [PMID: 33936014 PMCID: PMC8079656 DOI: 10.3389/fmicb.2021.657753] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 03/26/2021] [Indexed: 11/24/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen that causes chronic, systemic infections, and the recalcitrance of these infections is mainly due to the presence of persister cells, which are a bacterial subpopulation that exhibits extreme, yet transient, antibiotic tolerance accompanied by a transient halt in growth. However, upon cessation of antibiotic treatment, a resumption in growth of persister cells causes recurrence of infections and treatment failure. Previously, we reported the involvement of msaABCR in several important staphylococcal phenotypes, including the formation of persister cells. Additionally, observations of the regulation of several metabolic genes by the msaABCR operon in transcriptomics and proteomics analyses have suggested its role in the metabolic activities of S. aureus. Given the importance of metabolism in persister formation as our starting point, in this study we demonstrated how the msaABCR operon regulates energy metabolism and subsequent antibiotic tolerance. We showed that deletion of the msaABCR operon results in increased tricarboxylic acid (TCA) cycle activity, accompanied by increased cellular ATP content and higher NADH content in S. aureus cells. We also showed that msaABCR (through MsaB) represses the ccpE and ndh2 genes, thereby regulating TCA cycle activity and the generation of membrane potential, respectively. Together, the observations from this study led to the conclusion that msaABCR operon deletion induces a metabolically hyperactive state, leading to decreased persister formation in S. aureus.
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Affiliation(s)
- Shanti Pandey
- Center for Molecular and Cellular Biosciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Gyan S Sahukhal
- Center for Molecular and Cellular Biosciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Mohamed O Elasri
- Center for Molecular and Cellular Biosciences, The University of Southern Mississippi, Hattiesburg, MS, United States
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12
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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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Alarcón Elvira F, Pardío Sedas VT, Martínez Herrera D, Quintana Castro R, Oliart Ros RM, López Hernández K, Flores Primo A, Ramírez Elvira K. Comparative Survival and the Cold-Induced Gene Expression of Pathogenic and Nonpathogenic Vibrio Parahaemolyticus from Tropical Eastern Oysters during Cold Storage. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17061836. [PMID: 32178325 PMCID: PMC7143714 DOI: 10.3390/ijerph17061836] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Revised: 03/09/2020] [Accepted: 03/10/2020] [Indexed: 02/01/2023]
Abstract
Expression of the regulatory stress rpoS gene controls the transcription of cspA genes, which are involved in survival and adaptation to low temperatures. The purpose of this study was to assess the growth kinetics of naturally occurring V. parahaemolyticus in shellstock oysters and in vitro and the cold-shock-induced expression of the rpoS and cspA gene response in vitro during postharvest refrigeration. Naturally contaminated eastern oysters (Crassostrea virginica) and pathogenic (Vp-tdh) and nonpathogenic (Vp-tlh) isolates were stored at 7 ± 1 °C for 168 h and 216 h, respectively. The regulatory stress (rpos) and cold-shock (cspA) gene expressions were determined by reverse transcription PCR. At 24 h, the (Vp-tdh) strain grew faster (p < 0.05) than the (Vp-tlh) strain in oysters (λ = 0.33, 0.39, respectively) and in vitro (λ = 0.89, 37.65, respectively), indicating a better adaptation to cold shock for the (Vp-tdh) strain in live oysters and in vitro. At 24 h, the (Vp-tdh) strain rpoS and cspA gene expressions were upregulated by 1.9 and 2.3-fold, respectively, but the (Vp-tlh) strain rpoS and cspA gene expressions were repressed and upregulated by -0.024 and 1.9-fold, respectively. The V. parahaemolyticus strains that were isolated from tropical oysters have adaptive expression changes to survive and grow at 7 °C, according to their virulence.
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Affiliation(s)
- Francisco Alarcón Elvira
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Av. Miguel Ángel de Quevedo s/n esq. Yáñez, Col. Unidad Veracruzana, Veracruz, Ver. CP 91710, Mexico; (F.A.E.); (D.M.H.); (K.L.H.); (A.F.P.); (K.R.E.)
| | - Violeta T. Pardío Sedas
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Av. Miguel Ángel de Quevedo s/n esq. Yáñez, Col. Unidad Veracruzana, Veracruz, Ver. CP 91710, Mexico; (F.A.E.); (D.M.H.); (K.L.H.); (A.F.P.); (K.R.E.)
- Correspondence: ; Tel.: +52-229-9342075 (ext. 24125); Fax: +52-229-9342075 (ext. 24104)
| | - David Martínez Herrera
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Av. Miguel Ángel de Quevedo s/n esq. Yáñez, Col. Unidad Veracruzana, Veracruz, Ver. CP 91710, Mexico; (F.A.E.); (D.M.H.); (K.L.H.); (A.F.P.); (K.R.E.)
| | - Rodolfo Quintana Castro
- Facultad de Bioanálisis, Universidad Veracruzana, Calle Iturbide s/n, Col. Centro, Veracruz, Ver. CP 91700, Mexico;
| | - Rosa María Oliart Ros
- Unidad de Investigación y Desarrollo en Alimentos, Instituto Tecnológico de Veracruz, Av. Miguel A. de Quevedo 2779, Veracruz, Ver. 91897, Mexico;
| | - Karla López Hernández
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Av. Miguel Ángel de Quevedo s/n esq. Yáñez, Col. Unidad Veracruzana, Veracruz, Ver. CP 91710, Mexico; (F.A.E.); (D.M.H.); (K.L.H.); (A.F.P.); (K.R.E.)
| | - Argel Flores Primo
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Av. Miguel Ángel de Quevedo s/n esq. Yáñez, Col. Unidad Veracruzana, Veracruz, Ver. CP 91710, Mexico; (F.A.E.); (D.M.H.); (K.L.H.); (A.F.P.); (K.R.E.)
| | - Karen Ramírez Elvira
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Av. Miguel Ángel de Quevedo s/n esq. Yáñez, Col. Unidad Veracruzana, Veracruz, Ver. CP 91710, Mexico; (F.A.E.); (D.M.H.); (K.L.H.); (A.F.P.); (K.R.E.)
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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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15
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The msaABCR Operon Regulates the Response to Oxidative Stress in Staphylococcus aureus. J Bacteriol 2019; 201:JB.00417-19. [PMID: 31427392 DOI: 10.1128/jb.00417-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 08/05/2019] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus has evolved a complex regulatory network that controls a multitude of defense mechanisms against the deleterious effects of oxidative stress stimuli, subsequently leading to the pathogen's survival and persistence in the hosts. Previously, we characterized the msaABCR operon as a regulator of virulence, antibiotic resistance, and the formation of persister cells in S. aureus Deletion of the msaABCR operon resulted in the downregulation of several genes involved in resistance against oxidative stress. Notably, those included carotenoid biosynthetic genes and the ohr gene, which is involved in resistance against organic hydroperoxides. These findings led us to hypothesize that the msaABCR operon is involved in resisting oxidative stress generated in the presence of both H2O2 and organic hydroperoxides. Here, we report that a protein product of the msaABCR operon (MsaB) transcriptionally regulates the expression of the crtOPQMN operon and the ohr gene to resist in vitro oxidative stresses. In addition to its direct regulation of the crtOPQMN operon and ohr gene, we also show that MsaB is the transcriptional repressor of sarZ (repressor of ohr). Taken together, these results suggest that the msaABCR operon regulates an oxidative stress defense mechanism, which is required to facilitate persistent and recurrent staphylococcal infections. Moving forward, we plan to investigate the role of msaABCR in the persistence of S. aureus under in vivo conditions.IMPORTANCE This study shows the involvement of the msaABCR operon in resisting oxidative stress by Staphylococcus aureus generated under in vitro and ex vivo conditions. We show that MsaB regulates the expression and production of a carotenoid pigment, staphyloxanthin, which is a potent antioxidant in S. aureus We also demonstrate that MsaB regulates the ohr gene, which is involved in defending against oxidative stress generated by organic hydroperoxides. This study highlights the importance of msaABCR in the survival of S. aureus in the presence of various environmental stimuli that mainly exert oxidative stress. The findings from this study indicate the possibility that msaABCR is involved in the persistence of staphylococcal infections and therefore could be a potential antimicrobial target to overcome recalcitrant staphylococcal infections.
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16
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G C B, Sahukhal GS, Elasri MO. Role of the msaABCR Operon in Cell Wall Biosynthesis, Autolysis, Integrity, and Antibiotic Resistance in Staphylococcus aureus. Antimicrob Agents Chemother 2019; 63:e00680-19. [PMID: 31307991 PMCID: PMC6761503 DOI: 10.1128/aac.00680-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/10/2019] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus is an important human pathogen in both community and health care settings. One of the challenges with S. aureus as a pathogen is its acquisition of antibiotic resistance. Previously, we showed that deletion of the msaABCR operon reduces cell wall thickness, resulting in decreased resistance to vancomycin in vancomycin-intermediate S. aureus (VISA). In this study, we investigated the nature of the cell wall defect in the msaABCR operon mutant in the Mu50 (VISA) and USA300 LAC methicillin-resistant Staphylococcus aureus (MRSA) strains. Results showed that msaABCR mutant cells had decreased cross-linking in both strains. This defect is typically due to increased murein hydrolase activity and/or nonspecific processing of murein hydrolases mediated by increased protease activity in mutant cells. The defect was enhanced by a decrease in teichoic acid content in the msaABCR mutant. Therefore, we propose that deletion of the msaABCR operon results in decreased peptidoglycan cross-linking, leading to increased susceptibility toward cell wall-targeting antibiotics, such as β-lactams and vancomycin. Moreover, we also observed significantly downregulated transcription of early cell wall-synthesizing genes, supporting the finding that msaABCR mutant cells have decreased peptidoglycan synthesis. More specifically, the msaABCR mutant in the USA300 LAC strain (MRSA) showed significantly reduced expression of the murA gene, whereas the msaABCR mutant in the Mu50 strain (VISA) showed significantly reduced expression of glmU, murA, and murD Thus, we conclude that the msaABCR operon controls the balance between cell wall synthesis and cell wall hydrolysis, which is required for maintaining a robust cell wall and acquiring resistance to cell wall-targeting antibiotics, such as vancomycin and the β-lactams.
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Affiliation(s)
- Bibek G C
- Cell and Molecular Biology, The University of Southern Mississippi, Hattiesburg, Mississippi, USA
| | - Gyan S Sahukhal
- Cell and Molecular Biology, The University of Southern Mississippi, Hattiesburg, Mississippi, USA
| | - Mohamed O Elasri
- Cell and Molecular Biology, The University of Southern Mississippi, Hattiesburg, Mississippi, USA
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17
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Keinhörster D, George SE, Weidenmaier C, Wolz C. Function and regulation of Staphylococcus aureus wall teichoic acids and capsular polysaccharides. Int J Med Microbiol 2019; 309:151333. [DOI: 10.1016/j.ijmm.2019.151333] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 07/09/2019] [Accepted: 07/17/2019] [Indexed: 01/05/2023] Open
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18
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Zhou W, Wang Z, Mo H, Zhao Y, Li H, Zhang H, Hu L, Zhou X. Thymol Mediates Bactericidal Activity against Staphylococcus aureus by Targeting an Aldo-Keto Reductase and Consequent Depletion of NADPH. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:8382-8392. [PMID: 31271032 DOI: 10.1021/acs.jafc.9b03517] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Staphylococcus aureus is a common pathogen that can cause life-threatening infections. Treatment of antibiotic-resistant S. aureus infection needs effective antibacterial agents. Thymol, a generally recognized safe natural compound, has potential as an alternative to treat S. aureus infections. However, the targets and mechanisms of action of thymol were not fully understood. Bioinformatics analysis showed that IolS, a predicted aldo-keto reductase (AKR) in S. aureus, could be a potential target of thymol. Isothermal titration calorimetry (ITC) analysis demonstrated that thymol directly binds IolS and amino acid residues (Y30 and L33) are essential for such binding. Deletion of IolS or mutation of Y30A and L33A reduced the bactericidal activity of thymol at the concentration of 200 μg/mL, suggesting that thymol mediates bactericidal activity via binding with IolS. Biochemical analysis showed that addition of thymol significantly increased AKR activity of IolS from 1.6 ± 0.1 to 2.4 ± 0.2 U (p < 0.05). The content of NADPH within S. aureus cells decreased significantly from 105 ± 5 to 72 ± 3 pmol/108 cells (p < 0.05) following thymol treatment at the concentration of 200 μg/mL. Importantly, addition of NADPH could alleviate the bactericidal effect of thymol on S. aureus, indicating that the depletion of NADPH is responsible for thymol-mediated bactericidal activity. Overall, these results demonstrated that thymol could directly bind IolS and increase its AKR activity, leading to the depletion of NADPH and bactericidal effect. AKR activity of IolS could be a promising target for the development of new antimicrobials.
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Affiliation(s)
- Wei Zhou
- School of Food Science , Henan Institute of Science and Technology , Xinxiang 453003 , Henan China
| | - Zhen Wang
- School of Food Science , Henan Institute of Science and Technology , Xinxiang 453003 , Henan China
| | - Haizhen Mo
- School of Food Science , Henan Institute of Science and Technology , Xinxiang 453003 , Henan China
| | - Yanyan Zhao
- School of Food Science , Henan Institute of Science and Technology , Xinxiang 453003 , Henan China
| | - Hongbo Li
- School of Food Science , Henan Institute of Science and Technology , Xinxiang 453003 , Henan China
| | - Hao Zhang
- School of Food Science , Henan Institute of Science and Technology , Xinxiang 453003 , Henan China
| | - Liangbin Hu
- School of Food Science , Henan Institute of Science and Technology , Xinxiang 453003 , Henan China
| | - Xiaohui Zhou
- Department of Pathobiology and Veterinary Science , University of Connecticut , Storrs , Connecticut 06269 , United States
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19
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Keinhörster D, Salzer A, Duque-Jaramillo A, George SE, Marincola G, Lee JC, Weidenmaier C, Wolz C. Revisiting the regulation of the capsular polysaccharide biosynthesis gene cluster in Staphylococcus aureus. Mol Microbiol 2019; 112:1083-1099. [PMID: 31283061 DOI: 10.1111/mmi.14347] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2019] [Indexed: 12/23/2022]
Abstract
Capsular polysaccharide (CP) biosynthesis in Staphylococcus aureus is tightly controlled resulting in a heterogeneous phenotype within a population and CP being mainly detectable in nongrowing cells. Expression of the corresponding biosynthesis gene cluster is driven by one promoter element (Pcap ). Here, we demonstrate that Pcap contains a main SigB-dependent promoter. The SigB consensus motif overlaps with a previously described inverted repeat (IR) that is crucial for cap expression. The essentiality of the IR is derived from this region acting as a SigB binding site rather than as an operator site for the proposed cap activators RbsR and MsaB. Furthermore, Pcap contains an extensive upstream region harboring a weak SigA-dependent promoter and binding sites for cap repressors such as SaeR, CodY and Rot. Heterogeneous CP synthesis is determined by SigB activity and repressor binding to the upstream region. SigB dependency and regulation by the upstream repressors are also sufficient to explain the temporal gene expression pattern at the transcriptional level. However, CP synthesis remains growth phase-dependent even when transcription is rendered constitutive, suggesting additional posttranscriptional regulatory circuits. Thus, the interference of multiple repressors with SigB-dependent promoter activity as well as post-transcriptional mechanisms ensure the appropriate regulation of CP synthesis.
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Affiliation(s)
- Daniela Keinhörster
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Andrea Salzer
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Alejandra Duque-Jaramillo
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Shilpa E George
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Gabriella Marincola
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Jean C Lee
- Department of Medicine (Infectious Diseases), Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Christopher Weidenmaier
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
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20
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Caballero CJ, Menendez-Gil P, Catalan-Moreno A, Vergara-Irigaray M, García B, Segura V, Irurzun N, Villanueva M, Ruiz de Los Mozos I, Solano C, Lasa I, Toledo-Arana A. The regulon of the RNA chaperone CspA and its auto-regulation in Staphylococcus aureus. Nucleic Acids Res 2019; 46:1345-1361. [PMID: 29309682 PMCID: PMC5815144 DOI: 10.1093/nar/gkx1284] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 12/18/2017] [Indexed: 12/21/2022] Open
Abstract
RNA-binding proteins (RBPs) are essential to fine-tune gene expression. RBPs containing the cold-shock domain are RNA chaperones that have been extensively studied. However, the RNA targets and specific functions for many of them remain elusive. Here, combining comparative proteomics and RBP-immunoprecipitation-microarray profiling, we have determined the regulon of the RNA chaperone CspA of Staphylococcus aureus. Functional analysis revealed that proteins involved in carbohydrate and ribonucleotide metabolism, stress response and virulence gene expression were affected by cspA deletion. Stress-associated phenotypes such as increased bacterial aggregation and diminished resistance to oxidative-stress stood out. Integration of the proteome and targetome showed that CspA post-transcriptionally modulates both positively and negatively the expression of its targets, denoting additional functions to the previously proposed translation enhancement. One of these repressed targets was its own mRNA, indicating the presence of a negative post-transcriptional feedback loop. CspA bound the 5′UTR of its own mRNA disrupting a hairpin, which was previously described as an RNase III target. Thus, deletion of the cspA 5′UTR abrogated mRNA processing and auto-regulation. We propose that CspA interacts through a U-rich motif, which is located at the RNase III cleavage site, portraying CspA as a putative RNase III-antagonist.
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Affiliation(s)
- Carlos J Caballero
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain
| | - Pilar Menendez-Gil
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain
| | - Arancha Catalan-Moreno
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain
| | - Marta Vergara-Irigaray
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain.,Navarrabiomed-Universidad Pública de Navarra (UPNA)-Complejo Hospitalario de Navarra (CHN), IDISNA. 31008 Pamplona, Navarra, Spain
| | - Begoña García
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain.,Navarrabiomed-Universidad Pública de Navarra (UPNA)-Complejo Hospitalario de Navarra (CHN), IDISNA. 31008 Pamplona, Navarra, Spain
| | - Víctor Segura
- Genomics, Proteomics and Bioinformatics Unit. Center for Applied Medical Research. University of Navarra. 31008 Pamplona, Spain
| | - Naiara Irurzun
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain
| | - Maite Villanueva
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain
| | - Igor Ruiz de Los Mozos
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain
| | - Cristina Solano
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain.,Navarrabiomed-Universidad Pública de Navarra (UPNA)-Complejo Hospitalario de Navarra (CHN), IDISNA. 31008 Pamplona, Navarra, Spain
| | - Iñigo Lasa
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain.,Navarrabiomed-Universidad Pública de Navarra (UPNA)-Complejo Hospitalario de Navarra (CHN), IDISNA. 31008 Pamplona, Navarra, Spain
| | - Alejandro Toledo-Arana
- Instituto de Agrobiotecnología. IDAB, CSIC-UPNA-Gobierno de Navarra. 31192-Mutilva, Navarra, Spain
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21
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Donegan NP, Manna AC, Tseng CW, Liu GY, Cheung AL. CspA regulation of Staphylococcus aureus carotenoid levels and σ B activity is controlled by YjbH and Spx. Mol Microbiol 2019; 112:532-551. [PMID: 31074903 DOI: 10.1111/mmi.14273] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2019] [Indexed: 01/06/2023]
Abstract
Staphyloxanthin, a carotenoid in S. aureus, is a powerful antioxidant against oxidative stresses. The crtOPQMN operon driving pigment synthesis is under the control of σB . CspA, a cold shock protein, is known to control σB activity. To ascertain genes that regulate cspA, we screened a transposon library that exhibited reduced cspA expression and pigmentation. We found that the adaptor protein YjbH activates cspA expression. Spx, the redox-sensitive transcriptional regulator and a proteolytic target for YjbH and ClpXP, complexes with αCTD of RNAP prior to binding the cspA promoter to repress cspA activity. Increased cspA expression in trans in the inactive spx C10A mutant of JE2 did not enhance pigment production while it did in JE2, suggesting that cspA is downstream to Spx in pigmentation control. As the staphyloxanthin pigment is critical to S. aureus survival in human hosts, we demonstrated that the cspA and yjbH mutants survived less well than the parent in whole blood killing assay. Collectively, our studies suggest a pathway wherein YjbH and ClpXP proteolytically cleave Spx, a repressor of cspA transcription, to affect σB -dependent carotenoid expression, thus providing a critical link between intracellular redox sensing by Spx and carotenoid production to improve S. aureus survival during infections.
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Affiliation(s)
- Niles P Donegan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Adhar C Manna
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Ching Wen Tseng
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - George Y Liu
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Ambrose L Cheung
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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Wu L, Ma L, Li X, Huang Z, Gao X. Contribution of the cold shock protein CspA to virulence in Xanthomonas oryzae pv. oryzae. MOLECULAR PLANT PATHOLOGY 2019; 20:382-391. [PMID: 30372574 PMCID: PMC6637868 DOI: 10.1111/mpp.12763] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Xanthomonas oryzae pv. oryzae (Xoo) causes a damaging bacterial leaf blight disease in rice. Cold shock proteins (Csps) are highly conserved nucleic acid-binding proteins present in various bacterial genera, but relatively little is known about their functions in Xanthomonas. Herein, we identified four Csps (CspA-CspD) in the Xoo PXO99A strain. Deletion of cspA decreased cold adaptation and a few known pathogenic factors, including bacterial pathogenicity, biofilm formation and polysaccharide production. Furthermore, we performed transcriptomic and chromosome immunoprecipitation (ChIP) experiments to identify direct targets of CspA and to determine its DNA-binding sequence. Integrative data analysis revealed that CspA directly regulates two genes, PXO_RS11830 and PXO_RS01060, by binding to a conserved CCAAT sequence in the promoter region. We generated single-deletion mutants of each gene and the results indicate that both are responsible for Xanthomonas pathogenicity. In addition, quantitative real-time polymerase chain reaction and western blotting showed that CspA suppressed the expression of its direct targets. In summary, our study clarifies the characteristics of Csps in Xanthomonas and greatly advances our understanding of the mechanisms underlying the contribution of CspA to bacterial virulence.
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Affiliation(s)
- Liming Wu
- College of Plant ProtectionNanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of EducationNanjing210095China
| | - Liumin Ma
- College of Plant ProtectionNanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of EducationNanjing210095China
| | - Xi Li
- College of Plant ProtectionNanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of EducationNanjing210095China
| | - Ziyang Huang
- College of Plant ProtectionNanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of EducationNanjing210095China
| | - Xuewen Gao
- College of Plant ProtectionNanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of EducationNanjing210095China
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MsaB and CodY Interact To Regulate Staphylococcus aureus Capsule in a Nutrient-Dependent Manner. J Bacteriol 2018; 200:JB.00294-18. [PMID: 29941424 DOI: 10.1128/jb.00294-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 06/19/2018] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus has a complex regulatory network for controlling the production of capsule polysaccharide. In S. aureus, capsule production is controlled by several regulators in response to various environmental stimuli. Previously, we described MsaB as a new regulator that specifically binds to the cap promoter in a growth phase- or nutrient-dependent manner. In addition to MsaB, several other regulators have also been shown to bind the same region. In this study, we examined the interactions between MsaB and other nutrient-sensing regulators (CodY and CcpE) with respect to binding to the cap promoter in a nutrient-dependent manner. We observed that msaABCR and ccpE interact in a complex fashion to regulate capsule production. However, we confirmed that ccpE does not bind cap directly. We also defined the regulatory relationship between msaABCR and CodY. When nutrients (branched-chain amino acids) are abundant, CodY binds to the promoter region of the cap operon and represses its transcription. However, when nutrient concentrations decrease, MsaB, rather than CodY, binds to the cap promoter. Binding of MsaB to the cap promoter activates transcription of the cap operon. We hypothesize that this same mechanism may be used by S. aureus to regulate other virulence factors.IMPORTANCE Findings from this study define the mechanism of regulation of capsule production in Staphylococcus aureus Specifically, we show that two key regulators, MsaB and CodY, coordinate their functions to control the expression of capsule in response to nutrients. S. aureus fine-tunes the production of capsule by coordinating the activity of several regulators and by sensing nutrient levels. This study demonstrates the importance of incorporating multiple inputs prior to the expression of costly virulence factors, such as capsule.
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Guanine Limitation Results in CodY-Dependent and -Independent Alteration of Staphylococcus aureus Physiology and Gene Expression. J Bacteriol 2018; 200:JB.00136-18. [PMID: 29712876 DOI: 10.1128/jb.00136-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/25/2018] [Indexed: 02/03/2023] Open
Abstract
In Staphylococcus aureus, the global transcriptional regulator CodY modulates the expression of hundreds of genes in response to the availability of GTP and the branched-chain amino acids isoleucine, leucine, and valine (ILV). CodY DNA-binding activity is high when GTP and ILV are abundant. When GTP and ILV are limited, CodY's affinity for DNA drops, altering expression of CodY-regulated targets. In this work, we investigated the impact of guanine nucleotides (GNs) on S. aureus physiology and CodY activity by constructing a guaA null mutant (ΔguaA strain). De novo biosynthesis of guanine monophosphate is abolished due to the guaA mutation; thus, the mutant cells require exogenous guanosine for growth. We also found that CodY activity was reduced when we knocked out guaA, activating the Agr two-component system and increasing secreted protease activity. Notably, in a rich, complex medium, we detected an increase in alternative sigma factor B activity in the ΔguaA mutant, which results in a 5-fold increase in production of the antioxidant pigment staphyloxanthin. Under biologically relevant flow conditions, ΔguaA cells failed to form robust biofilms when limited for guanine or guanosine. Transcriptome sequencing (RNA-Seq) analysis of the S. aureus transcriptome during growth in guanosine-limited chemostats revealed substantial CodY-dependent and -independent alterations of gene expression profiles. Importantly, these changes increase production of proteases and δ-toxin, suggesting that S. aureus exhibits a more invasive lifestyle when limited for guanosine. Further, gene products upregulated under GN limitation, including those necessary for lipoic acid biosynthesis and sugar transport, may prove to be useful drug targets for treating Gram-positive infections.IMPORTANCE Staphylococcus aureus infections impose a serious economic burden on health care facilities and patients because of the emergence of strains resistant to last-line antibiotics. Understanding the physiological processes governing fitness and virulence of S. aureus in response to environmental cues is critical for developing efficient diagnostics and treatments. De novo purine biosynthesis is essential for both fitness and virulence in S. aureus since inhibiting production cripples S. aureus's ability to cause infection. Here, we corroborate these findings and show that blocking guanine nucleotide synthesis severely affects S. aureus fitness by altering metabolic and virulence gene expression. Characterizing pathways and gene products upregulated in response to guanine limitation can aid in the development of novel adjuvant strategies to combat S. aureus infections.
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Sahukhal GS, Pandey S, Elasri MO. msaABCR operon is involved in persister cell formation in Staphylococcus aureus. BMC Microbiol 2017; 17:218. [PMID: 29166860 PMCID: PMC5700755 DOI: 10.1186/s12866-017-1129-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/15/2017] [Indexed: 02/02/2023] Open
Abstract
Background Persister cells comprise a phenotypic variant that shows extreme antibiotic tolerance resulting in treatment failures of bacterial infections. While this phenomenon has posed a great threat in public health, mechanisms underlying their formation in Staphylococcus aureus remain largely unknown. Increasing evidences of the presence of persister cells in recalcitrant infections underscores the great urgency to unravel the mechanism by which these cells develop. Previously, we characterized msaABCR operon that plays roles in regulation of virulence, biofilm development and antibiotic resistance. We also characterized the function of MsaB protein and showed that MsaB is a putative transcription factor that binds target DNA in response to nutrients availability. Results In this study, we compared the number of persister cell in wild type, msaABCR deletion mutant and the complemented strain in two backgrounds USA300 LAC and Mu50. Herein, we report that msaABCR deletion mutant forms significantly less number of persister cells relative to wild type after challenge with various antibiotics in planktonic and biofilm growth conditions. Complementation of the msaABCR operon restored wild type phenotype. Combined antibiotic therapy along with msaABCR deletion significantly improves the killing kinetics of stationary phase and biofilm S. aureus cells. Transcriptomics analysis showed that msaABCR regulates several metabolic genes, transcription factors, transporters and enzymes that may play role in persister cells formation, which we seek to define in the future. Conclusions This study presented a new regulator, msaABCR operon, that is involved in the persister cells formation, which is a poorly understood in S. aureus. Indeed, we showed that msaABCR deletion significantly reduces the persister cells formation in all growth phases tested. Although, we have not yet defined the mechanism, we have shown that msaABCR regulates several metabolic, transporters, and extracellular proteases genes that have been previously linked with persister cells formation in other bacterial systems. Taken together, this study showed that inactivation of the msaABCR operon enhances the effectiveness of antibiotics for the treatment of S. aureus infections, especially in context of persister cells. Electronic supplementary material The online version of this article (10.1186/s12866-017-1129-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gyan S Sahukhal
- Department of Biological Sciences, The University of Southern Mississippi, 118 College Drive # 5018, Hattiesburg, MS, 39406-0001, USA
| | - Shanti Pandey
- Department of Biological Sciences, The University of Southern Mississippi, 118 College Drive # 5018, Hattiesburg, MS, 39406-0001, USA
| | - Mohamed O Elasri
- Department of Biological Sciences, The University of Southern Mississippi, 118 College Drive # 5018, Hattiesburg, MS, 39406-0001, USA.
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Eshwar AK, Guldimann C, Oevermann A, Tasara T. Cold-Shock Domain Family Proteins (Csps) Are Involved in Regulation of Virulence, Cellular Aggregation, and Flagella-Based Motility in Listeria monocytogenes. Front Cell Infect Microbiol 2017; 7:453. [PMID: 29124040 PMCID: PMC5662587 DOI: 10.3389/fcimb.2017.00453] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 10/04/2017] [Indexed: 11/13/2022] Open
Abstract
Cold shock-domain family proteins (Csps) are highly conserved nucleic acid binding proteins regulating the expression of various genes including those involved in stress resistance and virulence in bacteria. We show here that Csps are involved in virulence, cell aggregation and flagella-based extracellular motility of Listeria monocytogenes. A L. monocytogenes mutant deleted in all three csp genes (ΔcspABD) is attenuated with respect to human macrophage infection as well as virulence in a zebrafish infection model. Moreover, this mutant is incapable of aggregation and fails to express surface flagella or exhibit swarming motility. An evaluation of double csp gene deletion mutant (ΔcspBD, ΔcspAD and ΔcspAB) strains that produce single csp genes showed that there is redundancy as well as functional differences among the three L. monocytogenes Csps in their contributions to virulence, cellular aggregation, flagella production, and swarming motility. Protein and mRNA expression analysis further showed impaired expression of key virulence and motility genes in the csp mutants. Our observations at protein and mRNA level suggest Csp-dependent expression regulation of these genes at transcriptional and post-transcriptional levels. In a mutant lacking all csp genes (ΔcspABD) as well as those possessing single csp genes (ΔcspBD, ΔcspAD, and ΔcspAB) we detected reduced levels of proteins or activity as well as transcripts from the prfA, hly, mpl, and plcA genes suggesting a Csp-dependent transcriptional regulation of these genes. These csp mutants also had reduced or completely lacked ActA proteins and cell surface flagella but contained elevated actA and flaA mRNA levels compared to the parental wild type strain suggesting Csp involvement in post-transcriptional regulation of these genes. Overall, our results suggest that Csps contribute to the expression regulation of virulence and flagella-associated genes thereby promoting host pathogenicity, cell aggregation and flagella-based motility processes in L. monocytogenes.
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Affiliation(s)
- Athmanya K. Eshwar
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Claudia Guldimann
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Anna Oevermann
- Neuropathology—Division of Neurological Sciences, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Taurai Tasara
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Uppalapati CK, Gutierrez KD, Buss-Valley G, Katzif S. Growth-dependent activity of the cold shock cspA promoter + 5' UTR and production of the protein CspA in Staphylococcus aureus Newman. BMC Res Notes 2017; 10:232. [PMID: 28655334 PMCID: PMC5488409 DOI: 10.1186/s13104-017-2557-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 06/19/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Research involving the cold shock gene cspA of the medically important bacterium Staphylococcus aureus is steadily increasing as the relationships between the activity of this gene at 37 °C and a spectrum of virulence factors (e.g., biofilm formation, capsule production) as well as stress-related genes (e.g., alkaline shock protein, asp-23 and the alternative sigma factor, sigB) are distinguished. Fundamental to each of these discoveries is defining the regulation of cspA and the production of its protein product CspA. RESULTS In this paper, primer extension analysis was used to identify a transcriptional start point at 112 bp upstream of the initiation codon of the cspA coding sequence from S. aureus Newman RNA collected at 37 °C. Based on the location of the putative -10 and -35 sites as well as putative cold shock protein binding sites, a 192 bp sequence containing an 80 bp promoter + a 112 bp 5' UTR was generated by polymerase chain reaction. The activity of this 192 bp sequence was confirmed in a pLL38 promoter::xylE reporter gene construct. In addition, Western blots were used to confirm the production of CspA at 37 °C and demonstrated that production of the protein was not constitutive but showed growth-dependent production with a significant increase at the 6 h time point. CONCLUSIONS The results presented identify another regulatory region for the cold shock gene cspA of S. aureus and show growth-dependent activity of both this cspA regulatory sequence, presented as a 192 bp sequence of promoter + 5' UTR and the production of the CspA protein at 37 °C. The presence of two active transcription start points, a -112 bp sequence defined in this work and a second previously defined at -514 bp upstream of the cspA initiation codon, suggests the possibility of interactions between these two regions in the regulation of cspA. The growth-dependent production of the cold shock protein CspA supports the availability of this protein to be a modulator of virulence and stress factor genes at 37 °C.
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Affiliation(s)
- Chandana K Uppalapati
- Department of Microbiology and Immunology, Midwestern University, Glendale, AZ, 85308, USA
| | | | - Gina Buss-Valley
- Department of Microbiology and Immunology, Midwestern University, Glendale, AZ, 85308, USA
| | - Sam Katzif
- Department of Microbiology and Immunology, Midwestern University, Glendale, AZ, 85308, USA.
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Figueiredo AMS, Ferreira FA, Beltrame CO, Côrtes MF. The role of biofilms in persistent infections and factors involved in ica-independent biofilm development and gene regulation in Staphylococcus aureus. Crit Rev Microbiol 2017; 43:602-620. [PMID: 28581360 DOI: 10.1080/1040841x.2017.1282941] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Staphylococcus aureus biofilms represent a unique micro-environment that directly contribute to the bacterial fitness within hospital settings. The accumulation of this structure on implanted medical devices has frequently caused the development of persistent and chronic S. aureus-associated infections, which represent an important social and economic burden worldwide. ica-independent biofilms are composed of an assortment of bacterial products and modulated by a multifaceted and overlapping regulatory network; therefore, biofilm composition can vary among S. aureus strains. In the microniches formed by biofilms-produced by a number of bacterial species and composed by different structural components-drug refractory cell subpopulations with distinct physiological characteristics can emerge and result in therapeutic failures in patients with recalcitrant bacterial infections. In this review, we highlight the importance of biofilms in the development of persistence and chronicity in some S. aureus diseases, the main molecules associated with ica-independent biofilm development and the regulatory mechanisms that modulate ica-independent biofilm production, accumulation, and dispersion.
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Affiliation(s)
- Agnes Marie Sá Figueiredo
- a Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes , Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil
| | - Fabienne Antunes Ferreira
- b Departamento de Microbiologia, Imunologia e Parasitologia , Campus Universitário Setor F, Bloco A. Florianópolis, Universidade Federal de Santa Catarina , Florianopolis , Brazil
| | - Cristiana Ossaille Beltrame
- a Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes , Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil
| | - Marina Farrel Côrtes
- a Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes , Universidade Federal do Rio de Janeiro , Rio de Janeiro , Brazil
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Oyama T, Miyazaki M, Yoshimura M, Takata T, Ohjimi H, Jimi S. Biofilm-Forming Methicillin-Resistant Staphylococcus aureus Survive in Kupffer Cells and Exhibit High Virulence in Mice. Toxins (Basel) 2016; 8:toxins8070198. [PMID: 27376326 PMCID: PMC4963831 DOI: 10.3390/toxins8070198] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/15/2016] [Accepted: 06/24/2016] [Indexed: 11/26/2022] Open
Abstract
Although Staphylococcus aureus is part of the normal body flora, heavy usage of antibiotics has resulted in the emergence of methicillin-resistant strains (MRSA). MRSA can form biofilms and cause indwelling foreign body infections, bacteremia, soft tissue infections, endocarditis, and osteomyelitis. Using an in vitro assay, we screened 173 clinical blood isolates of MRSA and selected 20 high-biofilm formers (H-BF) and low-biofilm formers (L-BF). These were intravenously administered to mice and the general condition of mice, the distribution of bacteria, and biofilm in the liver, lung, spleen, and kidney were investigated. MRSA count was the highest in the liver, especially within Kupffer cells, which were positive for acid polysaccharides that are associated with intracellular biofilm. After 24 h, the general condition of the mice worsened significantly in the H-BF group. In the liver, bacterial deposition and aggregation and the biofilm-forming spot number were all significantly greater for H-BF group than for L-BF. CFU analysis revealed that bacteria in the H-BF group survived for long periods in the liver. These results indicate that the biofilm-forming ability of MRSA is a crucial factor for intracellular persistence, which could lead to chronic infections.
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Affiliation(s)
- Takuto Oyama
- Department of Plastic, Reconstructive and Aesthetic Surgery, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan.
| | - Motoyasu Miyazaki
- Department of Pharmacy, Fukuoka University Chikushi Hospital, Chikusino 818-8502, Japan.
| | - Michinobu Yoshimura
- Department of Medical Oncology, Hematology, and Infectious Diseases, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan.
| | - Tohru Takata
- Department of Medical Oncology, Hematology, and Infectious Diseases, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan.
| | - Hiroyuki Ohjimi
- Department of Plastic, Reconstructive and Aesthetic Surgery, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan.
| | - Shiro Jimi
- Central Laboratory for Pathology and Morphology, Department of Pathology, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan.
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Batte JL, Samanta D, Elasri MO. MsaB activates capsule production at the transcription level in Staphylococcus aureus. MICROBIOLOGY-SGM 2016; 162:575-589. [PMID: 26781313 DOI: 10.1099/mic.0.000243] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Staphylococcus aureus produces several virulence factors that allow it to cause a variety of infections. One of the major virulence factors is the capsule, which contributes to the survival of the pathogen within the host as a way to escape phagocytosis. The production of the capsular polysaccharide is encoded in a 16 gene operon, which is regulated in response to several environmental stimuli including nutrient availability. For instance, the capsule is produced in the late- and post-exponential growth phases, but not in the early- or mid-exponential growth phase. Several regulators are involved in capsule production, but the regulation of the cap operon is still poorly understood. In this study, we show that MsaB activates the cap operon by binding directly to a 10 bp repeat in the promoter region. We show that despite the fact that MsaB is expressed throughout four growth phases, it only activates capsule production in the late- and post-exponential growth phases. Furthermore, we find that MsaB does not bind to its target site in the early and mid-exponential growth phases. This correlates with decreased nutrient availability and capsule production. These data suggest either that MsaB binding ability changes in response to nutrients or that other cap operon regulators interfere with the binding of MsaB to its target site. This study increases our understanding of the regulation of capsule production and the mechanism of action of MsaB.
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Affiliation(s)
- Justin L Batte
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS, USA
| | - Dhritiman Samanta
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS, USA
| | - Mohamed O Elasri
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS, USA
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Sahukhal GS, Batte JL, Elasri MO. msaABCR operon positively regulates biofilm development by repressing proteases and autolysis in Staphylococcus aureus. FEMS Microbiol Lett 2015; 362:fnv006. [PMID: 25724778 DOI: 10.1093/femsle/fnv006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Staphylococcus aureus is an important human pathogen that causes nosocomial and community-acquired infections. One of the most important aspects of staphylococcal infections is biofilm development within the host, which renders the bacterium resistant to the host's immune response and antimicrobial agents. Biofilm development is very complex and involves several regulators that ensure cell survival on surfaces within the extracellular polymeric matrix. Previously, we identified the msaABCR operon as an additional positive regulator of biofilm formation. In this study, we define the regulatory pathway by which msaABCR controls biofilm formation. We demonstrate that the msaABCR operon is a negative regulator of proteases. The control of protease production mediates the processing of the major autolysin, Atl, and thus regulates the rate of autolysis. In the absence of the msaABCR operon, Atl is processed by proteases at a high rate, leading to increased cell death and a defect in biofilm maturation. We conclude that the msaABCR operon plays a key role in maintaining the balance between autolysis and growth within the staphylococcal biofilm.
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Affiliation(s)
- Gyan S Sahukhal
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406-0001, USA
| | - Justin L Batte
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406-0001, USA
| | - Mohamed O Elasri
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406-0001, USA
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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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