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Popova L, Carabetta VJ. The use of next-generation sequencing in personalized medicine. ARXIV 2024:arXiv:2403.03688v1. [PMID: 38495572 PMCID: PMC10942477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
The revolutionary progress in development of next-generation sequencing (NGS) technologies has made it possible to deliver accurate genomic information in a timely manner. Over the past several years, NGS has transformed biomedical and clinical research and found its application in the field of personalized medicine. Here we discuss the rise of personalized medicine and the history of NGS. We discuss current applications and uses of NGS in medicine, including infectious diseases, oncology, genomic medicine, and dermatology. We provide a brief discussion of selected studies where NGS was used to respond to wide variety of questions in biomedical research and clinical medicine. Finally, we discuss the challenges of implementing NGS into routine clinical use.
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Affiliation(s)
- Liya Popova
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden NJ, 08103
| | - Valerie J. Carabetta
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden NJ, 08103
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Reslane I, Handke LD, Watson GF, Shinde D, Ahn JS, Endres JL, Razvi F, Gilbert EA, Bayles KW, Thomas VC, Lehman MK, Fey PD. Glutamate -dependent arginine biosynthesis requires the inactivation of spoVG, sarA, and ahrC in Staphylococcus aureus. J Bacteriol 2024; 206:e0033723. [PMID: 38299858 PMCID: PMC10883023 DOI: 10.1128/jb.00337-23] [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: 10/13/2023] [Accepted: 01/09/2024] [Indexed: 02/02/2024] Open
Abstract
Genome sequencing has demonstrated that Staphylococcus aureus encodes arginine biosynthetic genes argDCJBFGH synthesizing proteins that mediate arginine biosynthesis using glutamate as a substrate. Paradoxically, however, S. aureus does not grow in a defined, glutamate-replete medium lacking arginine and glucose (CDM-R). Studies from our laboratory have found that specific mutations are selected by S. aureus that facilitate growth in CDM-R. However, these selected mutants synthesize arginine utilizing proline as a substrate rather than glutamate. In this study, we demonstrate that the ectopic expression of the argDCJB operon supports the growth of S. aureus in CDM-R, thus documenting the functionality of this pathway. Furthermore, suppressor mutants of S. aureus JE2 putA::Tn, which is defective in synthesizing arginine from proline, were selected on CDM-R agar. Genome sequencing revealed that these mutants had compensatory mutations within both spoVG, encoding an ortholog of the Bacillus subtilis stage V sporulation protein, and sarA, encoding the staphylococcal accessory regulator. Transcriptional studies document that argD expression is significantly increased when JE2 spoVG sarA was grown in CDM-R. Lastly, we found that a mutation in ahrC was required to induce argD expression in JE2 spoVG sarA when grown in an arginine-replete medium (CDM), suggesting that AhrC also functions to repress argDCJB in an arginine-dependent manner. In conclusion, these data indicate that the argDCJB operon is functional when transcribed in vitro and that SNPs within potential putative regulatory proteins are required to alleviate the repression.IMPORTANCEAlthough Staphylococcus aureus has the capability to synthesize all 20 amino acids, it is phenotypically auxotrophic for several amino acids including arginine. This work identifies putative regulatory proteins, including SpoVG, SarA, and AhrC, that function to inhibit the arginine biosynthetic pathways using glutamate as a substrate. Understanding the ultimate mechanisms of why S. aureus is selected to repress arginine biosynthetic pathways even in the absence of arginine will add to the growing body of work assessing the interactions between metabolism and S. aureus pathogenesis.
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Affiliation(s)
- Itidal Reslane
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Luke D. Handke
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Gabrielle F. Watson
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Dhananjay Shinde
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Jong-Sam Ahn
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Jennifer L. Endres
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Fareha Razvi
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Emily A. Gilbert
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Kenneth W. Bayles
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Vinai C. Thomas
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - McKenzie K. Lehman
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Paul D. Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
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Huber C, Wolf SA, Ziebuhr W, Holmes MA, Assmann J, Lübke-Becker A, Thürmer A, Semmler T, Brombach J, Bethe A, Bischoff M, Wieler LH, Epping L, Walther B. How to survive pig farming: Mechanism of SCC mec element deletion and metabolic stress adaptation in livestock-associated MRSA. Front Microbiol 2022; 13:969961. [PMID: 36504815 PMCID: PMC9728531 DOI: 10.3389/fmicb.2022.969961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 10/04/2022] [Indexed: 11/24/2022] Open
Abstract
Previous research on methicillin susceptible Staphylococcus aureus (MSSA) belonging to livestock-associated (LA-) sequence type (ST) 398, isolated from pigs and their local surroundings, indicated that differences between these MSSA and their methicillin resistant predecessors (MRSA) are often limited to the absence of the staphylococcal cassette chromosome mec (SCCmec) and few single nucleotide polymorphisms. So far, our understanding on how LA-MRSA endure the environmental conditions associated with pig-farming as well as the putative impact of this particular environment on the mobilisation of SCCmec elements is limited. Thus, we performed in-depth genomic and transcriptomic analyses using the LA-MRSA ST398 strain IMT38951 and its methicillin susceptible descendant. We identified a mosaic-structured SCCmec region including a putative replicative SCCmecVc which is absent from the MSSA chromosome through homologous recombination. Based on our data, such events occur between short repetitive sequences identified within and adjacent to two distinct alleles of the large cassette recombinase genes C (ccrC). We further evaluated the global transcriptomic response of MRSA ST398 to particular pig-farm associated conditions, i.e., contact with host proteins (porcine serum) and a high ammonia concentration. Differential expression of global regulators involved in stress response control were identified, i.e., ammonia-induced alternative sigma factor B-depending activation of genes for the alkaline shock protein 23, the heat shock response and the accessory gene regulator (agr)-controlled transcription of virulence factors. Exposure to serum transiently induced the transcription of distinct virulence factor encoding genes. Transcription of genes reported for mediating the loss of methicillin resistance, especially ccrC, was not significantly different compared to the unchallenged controls. We concluded that, from an evolutionary perspective, bacteria may save energy by incidentally dismissing a fully replicative SCCmec element in contrast to the induction of ccr genes on a population scale. Since the genomic SCCmec integration site is a hot-spot of recombination, occasional losses of elements of 16 kb size may restore capacities for the uptake of foreign genetic material. Subsequent spread of resistance, on the other hand, might depend on the autonomous replication machinery of the deleted SCCmec elements that probably enhance chances for reintegration of SCCmec into susceptible genomes by mere multiplication.
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Affiliation(s)
- Charlotte Huber
- Advanced Light and Electron Microscopy (ZBS4), Robert Koch Institute, Berlin, Germany
| | - Silver A. Wolf
- Genome Sequencing and Genomic Epidemiology (MF2), Robert Koch Institute, Berlin, Germany
| | - Wilma Ziebuhr
- Institute for Molecular Infection Biology, University of Würzburg, Würzburg, Germany
| | - Mark A. Holmes
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Julia Assmann
- Advanced Light and Electron Microscopy (ZBS4), Robert Koch Institute, Berlin, Germany
| | - Antina Lübke-Becker
- Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany
| | - Andrea Thürmer
- Genome Sequencing and Genomic Epidemiology (MF2), Robert Koch Institute, Berlin, Germany
| | - Torsten Semmler
- Genome Sequencing and Genomic Epidemiology (MF2), Robert Koch Institute, Berlin, Germany
| | - Julian Brombach
- Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany
| | - Astrid Bethe
- Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany
| | - Markus Bischoff
- Institute of Medical Microbiology and Hygiene, Saarland University, Homburg, Germany
| | - Lothar H. Wieler
- Methodology and Research Infrastructure, Robert Koch Institute, Berlin, Germany
| | - Lennard Epping
- Genome Sequencing and Genomic Epidemiology (MF2), Robert Koch Institute, Berlin, Germany
| | - Birgit Walther
- Advanced Light and Electron Microscopy (ZBS4), Robert Koch Institute, Berlin, Germany,*Correspondence: Birgit Walther,
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Menard G, Silard C, Suriray M, Rouillon A, Augagneur Y. Thirty Years of sRNA-Mediated Regulation in Staphylococcus aureus: From Initial Discoveries to In Vivo Biological Implications. Int J Mol Sci 2022; 23:ijms23137346. [PMID: 35806357 PMCID: PMC9266662 DOI: 10.3390/ijms23137346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/20/2022] [Accepted: 06/28/2022] [Indexed: 01/27/2023] Open
Abstract
Staphylococcus aureus is a widespread livestock and human pathogen that colonizes diverse microenvironments within its host. Its adaptation to the environmental conditions encountered within humans relies on coordinated gene expression. This requires a sophisticated regulatory network, among which regulatory RNAs (usually called sRNAs) have emerged as key players over the last 30 years. In S. aureus, sRNAs regulate target genes at the post-transcriptional level through base–pair interactions. The functional characterization of a subset revealed that they participate in all biological processes, including virulence, metabolic adaptation, and antibiotic resistance. In this review, we report 30 years of S. aureus sRNA studies, from their discovery to the in-depth characterizations of some of them. We also discuss their actual in vivo contribution, which is still lagging behind, and their place within the complex regulatory network. These shall be key aspects to consider in order to clearly uncover their in vivo biological functions.
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Affiliation(s)
- Guillaume Menard
- CHU Rennes, INSERM, BRM (Bacterial Regulatory RNAs and Medicine), SB2H (Service de Bactériologie Hygiène-Hospitalière), University Rennes, UMR_S 1230, F-35000 Rennes, France; (G.M.); (M.S.)
| | - Chloé Silard
- INSERM, BRM (Bacterial Regulatory RNAs and Medicine), University Rennes, UMR_S 1230, F-35000 Rennes, France; (C.S.); (A.R.)
| | - Marie Suriray
- CHU Rennes, INSERM, BRM (Bacterial Regulatory RNAs and Medicine), SB2H (Service de Bactériologie Hygiène-Hospitalière), University Rennes, UMR_S 1230, F-35000 Rennes, France; (G.M.); (M.S.)
| | - Astrid Rouillon
- INSERM, BRM (Bacterial Regulatory RNAs and Medicine), University Rennes, UMR_S 1230, F-35000 Rennes, France; (C.S.); (A.R.)
| | - Yoann Augagneur
- INSERM, BRM (Bacterial Regulatory RNAs and Medicine), University Rennes, UMR_S 1230, F-35000 Rennes, France; (C.S.); (A.R.)
- Correspondence: ; Tel.: +33-223234631
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The Transcription Factor SpoVG Is of Major Importance for Biofilm Formation of Staphylococcus epidermidis under In Vitro Conditions, but Dispensable for In Vivo Biofilm Formation. Int J Mol Sci 2022; 23:ijms23063255. [PMID: 35328675 PMCID: PMC8949118 DOI: 10.3390/ijms23063255] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 12/13/2022] Open
Abstract
Staphylococcus epidermidis is a common cause of device related infections on which pathogens form biofilms (i.e., multilayered cell populations embedded in an extracellular matrix). Here, we report that the transcription factor SpoVG is essential for the capacity of S. epidermidis to form such biofilms on artificial surfaces under in vitro conditions. Inactivation of spoVG in the polysaccharide intercellular adhesin (PIA) producing S. epidermidis strain 1457 yielded a mutant that, unlike its parental strain, failed to produce a clear biofilm in a microtiter plate-based static biofilm assay. A decreased biofilm formation capacity was also observed when 1457 ΔspoVG cells were co-cultured with polyurethane-based peripheral venous catheter fragments under dynamic conditions, while the cis-complemented 1457 ΔspoVG::spoVG derivative formed biofilms comparable to the levels seen with the wild-type. Transcriptional studies demonstrated that the deletion of spoVG significantly altered the expression of the intercellular adhesion (ica) locus by upregulating the transcription of the ica operon repressor icaR and down-regulating the transcription of icaADBC. Electrophoretic mobility shift assays (EMSA) revealed an interaction between SpoVG and the icaA-icaR intergenic region, suggesting SpoVG to promote biofilm formation of S. epidermidis by modulating ica expression. However, when mice were challenged with the 1457 ΔspoVG mutant in a foreign body infection model, only marginal differences in biomasses produced on the infected catheter fragments between the mutant and the parental strain were observed. These findings suggest that SpoVG is critical for the PIA-dependent biofilm formation of S. epidermis under in vitro conditions, but is largely dispensable for biofilm formation of this skin commensal under in vivo conditions.
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Abstract
The type VII protein secretion system (T7SS) of Staphylococcus aureus is encoded at the ess locus. T7 substrate recognition and protein transport are mediated by EssC, a membrane-bound multidomain ATPase. Four EssC sequence variants have been identified across S. aureus strains, each accompanied by a specific suite of substrate proteins. The ess genes are upregulated during persistent infection, and the secretion system contributes to virulence in disease models. It also plays a key role in intraspecies competition, secreting nuclease and membrane-depolarizing toxins that inhibit the growth of strains lacking neutralizing immunity proteins. A genomic survey indicates that the T7SS is widely conserved across staphylococci and is encoded in clusters that contain diverse arrays of toxin and immunity genes. The presence of genomic islands encoding multiple immunity proteins in species such as Staphylococcus warneri that lack the T7SS points to a major role for the secretion system in bacterial antagonism. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Lisa Bowman
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom; ,
| | - Tracy Palmer
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom; ,
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Huang Q, Zhang Z, Liu Q, Liu F, Liu Y, Zhang J, Wang G. SpoVG is an important regulator of sporulation and affects biofilm formation by regulating Spo0A transcription in Bacillus cereus 0-9. BMC Microbiol 2021; 21:172. [PMID: 34102998 PMCID: PMC8186074 DOI: 10.1186/s12866-021-02239-6] [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: 04/18/2021] [Accepted: 05/20/2021] [Indexed: 02/06/2023] Open
Abstract
Background Bacillus cereus 0–9, a Gram-positive, endospore-forming bacterium isolated from healthy wheat roots in our previous research, is considered to be an effective biocontrol strain against several soil-borne plant diseases. SpoVG, a regulator that is broadly conserved among many Gram-positive bacteria, may help this organism coordinate environmental growth and virulence to survive. This study aimed to explore the multiple functions of SpoVG in B. cereus 0–9. Methods The gene knockout strains were constructed by homologous recombination, and the sporulation process of B. cereus 0–9 and its mutants were observed by fluorescence staining method. We further determined the spore yields and biofilm formation abilities of test strains. Transcriptional fusion strains were constructed by overlapping PCR technique, and the promoter activity of the target gene was detected by measuring its fluorescence intensity. The biofilm production and colonial morphology of B. cereus 0–9 and its mutants were determined to study the functions of the target genes, and the transcription level of the target gene was determined by qRT-PCR. Results According to observation of the sporulation process of B. cereus 0–9 in germination medium, SpoVG is crucial for regulating sporulation stage V of B. cereus 0–9, which is identical to that of Bacillus subtilis but differs from that of Bacillus anthracis. In addition, SpoVG could influence biofilm formation of B. cereus 0–9. The transcription levels of two genes closely related to biofilm-formation, sipW and calY, were downregulated in a ΔspoVG mutant. The role of SpoVG in regulating biofilm formation was further explored by deleting the genes abrB and sinR in the ΔspoVG mutant, respectively, generating the double mutant strains ΔspoVGΔabrB and ΔspoVGΔsinR. The phenotypes of these double mutants were congruent with those of the single abrB and sinR deletion strains, respectively, which showed increased biofilm formation. This indicated that spoVG was located upstream of abrB and sinR in the regulatory pathway of B. cereus biofilm formation. Further, the results of qRT-PCR and the luminescence intensity of transcriptional fusion strains indicated that spoVG gene deletion could inhibit the transcription of Spo0A. Conclusions SpoVG, an important regulator in the sporulation of B. cereus, is located upstream of Spo0A and participates in regulation of biofilm formation of B. cereus 0–9 through regulating the transcription level of spo0A. Sporulation and biofilm formation are crucial mechanisms by which bacteria respond to adverse conditions. SpoVG is therefore an important regulator of Spo0A and is crucial for both sporulation and biofilm formation of B. cereus 0–9. This study provides a new insight into the regulatory mechanism of environmental adaptation in bacteria and a foundation for future studies on biofilm formation of B. cereus. Supplementary Information The online version contains supplementary material available at 10.1186/s12866-021-02239-6.
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Affiliation(s)
- Qiubin Huang
- Institute of Microbial Engineering, Laboratory of Bioresource and Applied Microbiology, School of Life Sciences, Henan University, Jinming Street, Kaifeng, 475004, China.,Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China
| | - Zhen Zhang
- Institute of Microbial Engineering, Laboratory of Bioresource and Applied Microbiology, School of Life Sciences, Henan University, Jinming Street, Kaifeng, 475004, China
| | - Qing Liu
- Institute of Microbial Engineering, Laboratory of Bioresource and Applied Microbiology, School of Life Sciences, Henan University, Jinming Street, Kaifeng, 475004, China
| | - Fengying Liu
- Institute of Microbial Engineering, Laboratory of Bioresource and Applied Microbiology, School of Life Sciences, Henan University, Jinming Street, Kaifeng, 475004, China.,Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China
| | - Yupeng Liu
- Institute of Microbial Engineering, Laboratory of Bioresource and Applied Microbiology, School of Life Sciences, Henan University, Jinming Street, Kaifeng, 475004, China.,Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China
| | - Juanmei Zhang
- Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China. .,School of Pharmaceutical, Henan Univeristy, Kaifeng, 475004, China.
| | - Gang Wang
- Institute of Microbial Engineering, Laboratory of Bioresource and Applied Microbiology, School of Life Sciences, Henan University, Jinming Street, Kaifeng, 475004, China. .,Engineering Research Center for Applied Microbiology of Henan Province, Kaifeng, 475004, China.
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SpoVG Modulates Cell Aggregation in Staphylococcus aureus by Regulating sasC Expression and Extracellular DNA Release. Appl Environ Microbiol 2020; 86:AEM.00591-20. [PMID: 32444467 PMCID: PMC7376557 DOI: 10.1128/aem.00591-20] [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] [Received: 03/10/2020] [Accepted: 05/06/2020] [Indexed: 11/20/2022] Open
Abstract
This study revealed that SpoVG can modulate cell aggregation by repressing sasC expression and extracellular DNA (eDNA) release. Furthermore, we have demonstrated the potential linkage between cell aggregation and antibiotic resistance. Our findings provide novel insights into the regulatory mechanisms of SpoVG involved in cell aggregation and in biofilm development and formation in Staphylococcus aureus. Biofilm formation is involved in numerous Staphylococcus aureus infections such as endocarditis, septic arthritis, osteomyelitis, and infections of indwelling medical devices. In these diseases, S. aureus forms biofilms as cell aggregates interspersed in host matrix material. Here, we have observed that the level of cell aggregation was significantly higher in the isogenic spoVG-deletion strain than in the wild-type strain. Reverse transcription-quantitative PCR data indicated that SpoVG could repress the expression of sasC, which codes for S. aureus surface protein C and is involved in cell aggregation and biofilm accumulation. Electromagnetic mobility shift assay demonstrated that SpoVG could specifically bind to the promoter region of sasC, indicating that SpoVG is a negative regulator and directly represses the expression of sasC. In addition, deletion of the SasC aggregation domain in the spoVG-deletion strain indicated that high-level expression of sasC could be the underlying cause of significantly increased cell aggregation formation. Our previous study showed that SpoVG is involved in oxacillin resistance of methicillin-resistant S. aureus by regulating the expression of genes involved in cell wall synthesis and degradation. In this study, we also found that SpoVG was able to negatively modulate the S. aureus drug tolerance under conditions of a high concentration of oxacillin treatment. These findings can broaden our understanding of the regulation of biofilm formation and drug tolerance in S. aureus. IMPORTANCE This study revealed that SpoVG can modulate cell aggregation by repressing sasC expression and extracellular DNA (eDNA) release. Furthermore, we have demonstrated the potential linkage between cell aggregation and antibiotic resistance. Our findings provide novel insights into the regulatory mechanisms of SpoVG involved in cell aggregation and in biofilm development and formation in Staphylococcus aureus.
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Subramanian D, Bhasuran B, Natarajan J. Genomic analysis of RNA-Seq and sRNA-Seq data identifies potential regulatory sRNAs and their functional roles in Staphylococcus aureus. Genomics 2019; 111:1431-1446. [DOI: 10.1016/j.ygeno.2018.09.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 09/21/2018] [Accepted: 09/26/2018] [Indexed: 12/17/2022]
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Supa-Amornkul S, Mongkolsuk P, Summpunn P, Chaiyakunvat P, Navaratdusit W, Jiarpinitnun C, Chaturongakul S. Alternative Sigma Factor B in Bovine Mastitis-Causing Staphylococcus aureus: Characterization of Its Role in Biofilm Formation, Resistance to Hydrogen Peroxide Stress, Regulon Members. Front Microbiol 2019; 10:2493. [PMID: 31787937 PMCID: PMC6853994 DOI: 10.3389/fmicb.2019.02493] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/16/2019] [Indexed: 12/24/2022] Open
Abstract
This study examines treatments of the bacterial pathogen Staphylococcus aureus, namely, in the context of its being a major cause of subclinical bovine mastitis. Such infections caused by S. aureus among dairy cows are difficult to detect and can easily become chronic, leading to reduced productivity and large losses for dairy manufacturers. In this study, the role of alternative sigma factor B (σB), which has been shown to be a global regulator for S. aureus infections, was explored in a mastitis-causing S. aureus strain, RF122. For comparison with the wild-type strain, a sigB null (ΔsigB) mutant was constructed and analyzed for its phenotypes and transcriptome. Our study found that σB is essential for biofilm formation as the ΔsigB mutant strain produced significantly less biofilm than did the wild-type strain at 48 h. σB is involved in response to H2O2 stress. However, σB plays a minor or no role in resistance to antiseptics (e.g., povidone-iodine and chlorhexidine), resistance to tested antibiotics, hemolysin activity, and invasion ability. RNA sequencing identified 225 σB-dependent genes, of which 171 are positively regulated and 54 are negatively regulated. The identified genes are involved in stress response, pathogenesis, and metabolic mechanisms. Quantitative TaqMan RT-PCR was performed to verify the RNA sequencing results; i.e., σB is a positive regulator for asp23, sarA, katA, yabJ, sodA, SAB2006c, and nrdD expressions. In the RF122 strain, σB plays a role in biofilm formation, general stress response (e.g., H2O2), and regulation of virulence factors and virulence-associated genes.
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Affiliation(s)
- Sirirak Supa-Amornkul
- Mahidol International Dental School, Faculty of Dentistry, Mahidol University, Bangkok, Thailand
| | - Paninee Mongkolsuk
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Pijug Summpunn
- Food Technology and Innovation Research Center of Excellence, School of Agricultural Technology, Walailak University, Nakhon Si Thammarat, Thailand
| | - Pongkorn Chaiyakunvat
- Department of Chemistry and Center for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Warisara Navaratdusit
- Department of Chemistry and Center for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Chutima Jiarpinitnun
- Department of Chemistry and Center for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Soraya Chaturongakul
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand
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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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12
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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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13
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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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14
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Huang L, Zuo Y, Jiang Q, Su Y, Qin Y, Xu X, Zhao L, Yan Q. A metabolomic investigation into the temperature-dependent virulence of Pseudomonas plecoglossicida from large yellow croaker (Pseudosciaena crocea). JOURNAL OF FISH DISEASES 2019; 42:431-446. [PMID: 30659613 DOI: 10.1111/jfd.12957] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
Pseudomonas plecoglossicida is associated with multiple fish diseases, and temperature is one of the most important environmental factors related to its outbreak. To elucidate the influence of temperature variation on the pathogen, the global metabolomics of P. plecoglossicida (NZBD9) were analysed at the virulent (18°C) and avirulent (12°C and 28°C) temperatures. The result showed that the levels of Phosphoric acid, Tyrosine, Spermidine and Sucrose were significantly reduced,while Itaconic acid, Glucaric acid and Isomaltose were increased in P. plecoglossicida at 18°C. These metabolic adjustments assist P. plecoglossicida to survive in adverse environments, proliferate in the host, colonize and resist host immune clearance during the initial steps of infection. The results suggested that L321_03626 and L321_18122 genes played a key role in the regulation of these metabolic adaptions and thus regulated P. plecoglossicida virulence at virulent temperature, which was proved by further gene silencing and artificial infection. The present study, for the first time, determines the P. plecoglossicida metabolomic responses to temperature variation, which is helpful to explore its pathogenic mechanism and provides reference for disease control.
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Affiliation(s)
- Lixing Huang
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Yanfei Zuo
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingling Jiang
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Yongquan Su
- State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China
| | - Yingxue Qin
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Xiaojin Xu
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Lingmin Zhao
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingpi Yan
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
- State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China
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15
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Mitsuwan W, Jiménez-Munguía I, Visutthi M, Sianglum W, Rodríguez-Ortega MJ, Voravuthikunchai SP. Rhodomyrtone decreases Staphylococcus aureus SigB activity during exponentially growing phase and inhibits haemolytic activity within membrane vesicles. Microb Pathog 2019; 128:112-118. [PMID: 30583020 DOI: 10.1016/j.micpath.2018.12.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/07/2018] [Accepted: 12/11/2018] [Indexed: 02/05/2023]
Abstract
Sigma factor B (SigB) controls the expression of Staphylococcus aureus genes including virulence factors and plays a role in the bacterial secretion system through membrane vesicle production. Inhibition of SigB could attenuate SigB dependent virulence and secretion system. The objective of this study was to determine the effects of rhodomyrtone on SigB and virulence factors related to SigB. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of rhodomyrtone against 67 clinical methicillin-resistant S. aureus isolates were 0.25-8 μg/ml, which were similar to those of vancomycin. Using luciferase gene fused to SigB dependent promoters of asp23, five time reduction in SigB activity was observed when the bacteria were treated with rhodomyrtone for 3 h. Rhodomyrtone significantly reduced SigB activity in a concentration dependent manner in exponentially growing cells (P < 0.05). In addition, sigB mutant was more sensitive towards increasing concentrations of rhodomyrtone than the wild type and yabJ-spoVG mutant. Rhodomyrtone at 0.625 μg/ml reduced the growth of sigB mutant by approximately 99%, compared with the yabJ-spoVG mutant and the wild type. Membrane vesicles were significantly reduced in the bacterial cells when treated with 0.5 × MIC rhodomyrtone (P < 0.05). Decreased haemolytic activity was detected within rhodomyrtone-treated membrane vesicles. The results indicated that rhodomyrtone inhibited S. aureus SigB activity during exponentially growing phase and inhibited haemolytic activity within membrane vesicles.
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Affiliation(s)
- Watcharapong Mitsuwan
- Department of Microbiology and Excellent Research Laboratory on Natural Products and Natural Product Research Center of Excellence, Faculty of Science, Prince of Songkla University, Songkhla, Thailand
| | - Irene Jiménez-Munguía
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus de Excelencia Internacional CeiA3, Córdoba, Spain; Department of Engineering of Technological Equipment, National University of Science and Technology "MISiS", Moscow, Russia
| | - Monton Visutthi
- Department of Microbiology and Excellent Research Laboratory on Natural Products and Natural Product Research Center of Excellence, Faculty of Science, Prince of Songkla University, Songkhla, Thailand
| | - Wipawadee Sianglum
- Department of Microbiology and Excellent Research Laboratory on Natural Products and Natural Product Research Center of Excellence, Faculty of Science, Prince of Songkla University, Songkhla, Thailand
| | | | - Manuel J Rodríguez-Ortega
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus de Excelencia Internacional CeiA3, Córdoba, Spain
| | - Supayang P Voravuthikunchai
- Department of Microbiology and Excellent Research Laboratory on Natural Products and Natural Product Research Center of Excellence, Faculty of Science, Prince of Songkla University, Songkhla, Thailand.
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16
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Mohamed N, Timofeyeva Y, Jamrozy D, Rojas E, Hao L, Silmon de Monerri NC, Hawkins J, Singh G, Cai B, Liberator P, Sebastian S, Donald RGK, Scully IL, Jones CH, Creech CB, Thomsen I, Parkhill J, Peacock SJ, Jansen KU, Holden MTG, Anderson AS. Molecular epidemiology and expression of capsular polysaccharides in Staphylococcus aureus clinical isolates in the United States. PLoS One 2019; 14:e0208356. [PMID: 30641545 PMCID: PMC6331205 DOI: 10.1371/journal.pone.0208356] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 11/15/2018] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus capsular polysaccharides (CP) are important virulence factors under evaluation as vaccine antigens. Clinical S. aureus isolates have the biosynthetic capability to express either CP5 or CP8 and an understanding of the relationship between CP genotype/phenotype and S. aureus epidemiology is valuable. Using whole genome sequencing, the clonal relatedness and CP genotype were evaluated for disease-associated S. aureus isolates selected from the Tigecycline Evaluation and Surveillance Trial (T.E.S.T) to represent different geographic regions in the United States (US) during 2004 and 2009–10. Thirteen prominent clonal complexes (CC) were identified, with CC5, 8, 30 and 45 representing >80% of disease isolates. CC5 and CC8 isolates were CP type 5 and, CC30 and CC45 isolates were CP type 8. Representative isolates from prevalent CC were susceptible to in vitro opsonophagocytic killing elicited by anti-CP antibodies, demonstrating that susceptibility to opsonic killing is not linked to the genetic lineage. However, as not all S. aureus isolates may express CP, isolates representing the diversity of disease isolates were assessed for CP production. While approximately 35% of isolates (primarily CC8) did not express CP in vitro, CP expression could be clearly demonstrated in vivo for 77% of a subset of these isolates (n = 20) despite the presence of mutations within the capsule operon. CP expression in vivo was also confirmed indirectly by measuring an increase in CP specific antibodies in mice infected with CP5 or CP8 isolates. Detection of antigen expression in vivo in relevant disease states is important to support the inclusion of these antigens in vaccines. Our findings confirm the validity of CP as vaccine targets and the potential of CP-based vaccines to contribute to S. aureus disease prevention.
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Affiliation(s)
- Naglaa Mohamed
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Yekaterina Timofeyeva
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Dorota Jamrozy
- The Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Eduardo Rojas
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Li Hao
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | | | - Julio Hawkins
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Guy Singh
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Bing Cai
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Paul Liberator
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Shite Sebastian
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Robert G. K. Donald
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - Ingrid L. Scully
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - C. Hal Jones
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | - C. Buddy Creech
- Vanderbilt Vaccine Research Program, Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Isaac Thomsen
- Vanderbilt Vaccine Research Program, Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Julian Parkhill
- The Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Sharon J. Peacock
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Kathrin U. Jansen
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
| | | | - Annaliesa S. Anderson
- Pfizer Vaccine Research and Development, Pearl River, New York, United States of America
- * E-mail:
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17
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Zhu Q, Wen W, Wang W, Sun B. Transcriptional regulation of virulence factors Spa and ClfB by the SpoVG-Rot cascade in Staphylococcus aureus. Int J Med Microbiol 2018; 309:39-53. [PMID: 30392856 DOI: 10.1016/j.ijmm.2018.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 09/25/2018] [Accepted: 10/18/2018] [Indexed: 12/15/2022] Open
Abstract
Staphylococcus aureus can produce numerous surface proteins involved in the adhesion and internalization of host cells, immune evasion, and inflammation initiation. Among these surface proteins, the microbial surface components recognizing adhesive matrix molecules contain many crucial cell wall-anchored virulence factors. The Sar-family regulatory protein Rot has been reported to regulate many important extracellular virulence factors at the transcriptional level, including Spa and clumping factor B. SpoVG, a global regulator in S. aureus, is known to control the expression of numerous genes. Here, we demonstrate that SpoVG can positively regulate the transcription of rot by directly binding to its promoter. SpoVG can also positively regulate the transcription of spa and clfB through direct-binding to their promoters and in a Rot-mediated manner. Furthermore, SpoVG can positively modulate the human fibrinogen-binding ability of S. aureus. In addition, phosphorylation of SpoVG by the serine/threonine kinase, Stk1, can positively regulate its binding to the promoters of rot, spa, and clfB. The human cell infection assay showed that the adhesion and internalization abilities were reduced in the spoVG mutant strain in comparison to those in the wild-type strain. Collectively, our data reveal a SpoVG-Rot regulatory cascade and novel molecular mechanisms in the virulence control in S. aureus.
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Affiliation(s)
- Qing Zhu
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, China
| | - Wen Wen
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, China
| | - Wanying Wang
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, China
| | - Baolin Sun
- Division of Molecular Medicine, Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences, University of Science and Technology of China, China.
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18
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A novel chlorination-induced ribonuclease YabJ from Staphylococcus aureus. Biosci Rep 2018; 38:BSR20180768. [PMID: 30201692 PMCID: PMC6435465 DOI: 10.1042/bsr20180768] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 08/15/2018] [Accepted: 08/23/2018] [Indexed: 01/09/2023] Open
Abstract
The characteristic fold of a protein is the decisive factor for its biological function. However, small structural changes to amino acids can also affect their function, for example in the case of post-translational modification (PTM). Many different types of PTMs are known, but for some, including chlorination, studies elucidating their importance are limited. A recent study revealed that the YjgF/YER057c/UK114 family (YjgF family) member RidA from Escherichia coli shows chaperone activity after chlorination. Thus, to identify the functional and structural differences of RidA upon chlorination, we studied an RidA homolog from Staphylococcus aureus: YabJ. The overall structure of S. aureus YabJ was similar to other members of the YjgF family, showing deep pockets on its surface, and the residues composing the pockets were well conserved. S. aureus YabJ was highly stable after chlorination, and the chlorinated state is reversible by treatment with DTT. However, it shows no chaperone activity after chlorination. Instead, YabJ from S. aureus shows chlorination-induced ribonuclease activity, and the activity is diminished after subsequent reduction. Even though the yabJ genes from Staphylococcus and Bacillus are clustered with regulators that are expected to code nucleic acid-interacting proteins, the nucleic acid-related activity of bacterial RidA has not been identified before. From our study, we revealed the structure and function of S. aureus YabJ as a novel chlorination-activated ribonuclease. The present study will contribute to an in-depth understanding of chlorination as a PTM.
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Zhao X, Zhang Y, Huang X. Pathogenicity-island-encoded regulatory RNAs regulate bacterial virulence and pathogenesis. Microb Pathog 2018; 125:196-204. [PMID: 30227229 DOI: 10.1016/j.micpath.2018.09.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 08/16/2018] [Accepted: 09/14/2018] [Indexed: 02/07/2023]
Abstract
Bacterial regulatory RNAs (regRNAs) have been widely studied for decades and shown to be involved in various aspects of bacterial survival, including their virulence and pathogenesis. Recently, many regRNAs have been found to be encoded within bacterial pathogenicity islands (PAIs). These PAI-encoded regRNAs also play important regulatory roles in bacterial virulence and pathogenesis. In this review, we introduce the reported PAI-encoded regRNAs individually, focusing on their types, target genes, regulatory roles, regulatory mechanisms and significance. We also summarize the virulence and pathogenesis of the pathogens concerned.
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Affiliation(s)
- Xin Zhao
- Department of Biochemistry and Molecular Biology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, 212013, China.
| | - Ying Zhang
- Department of Biochemistry and Molecular Biology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, 212013, China.
| | - Xinxiang Huang
- Department of Biochemistry and Molecular Biology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, 212013, China.
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20
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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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21
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Chan H, Ho J, Liu X, Zhang L, Wong SH, Chan MT, Wu WK. Potential and use of bacterial small RNAs to combat drug resistance: a systematic review. Infect Drug Resist 2017; 10:521-532. [PMID: 29290689 PMCID: PMC5736357 DOI: 10.2147/idr.s148444] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background Over the decades, new antibacterial agents have been developed in an attempt to combat drug resistance, but they remain unsuccessful. Recently, a novel class of bacterial gene expression regulators, bacterial small RNAs (sRNAs), has received increasing attention toward their involvement in antibiotic resistance. This systematic review aimed to discuss the potential of these small molecules as antibacterial drug targets. Methods Two investigators performed a comprehensive search of MEDLINE, EmBase, and ISI Web of Knowledge from inception to October 2016, without restriction on language. We included all in vitro and in vivo studies investigating the role of bacterial sRNA in antibiotic resistance. Risk of bias of the included studies was assessed by a modified guideline of Systematic Review Center for Laboratory Animal Experimentation (SYRCLE). Results Initial search yielded 432 articles. After exclusion of non-original articles, 20 were included in this review. Of these, all studies examined bacterial-type strains only. There were neither relevant in vivo nor clinical studies. The SYRCLE scores ranged from to 5 to 7, with an average of 5.9. This implies a moderate risk of bias. sRNAs influenced the antibiotics susceptibility through modulation of gene expression relevant to efflux pumps, cell wall synthesis, and membrane proteins. Conclusion Preclinical studies on bacterial-type strains suggest that modulation of sRNAs could enhance bacterial susceptibility to antibiotics. Further studies on clinical isolates and in vivo models are needed to elucidate the therapeutic value of sRNA modulation on treatment of multidrug-resistant bacterial infection.
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Affiliation(s)
- Hung Chan
- Department of Anesthesia and Intensive Care
| | - Jeffery Ho
- Department of Anesthesia and Intensive Care
| | | | - Lin Zhang
- Department of Anesthesia and Intensive Care.,State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences.,School of Biomedical Sciences, Faculty of Medicine
| | - Sunny Hei Wong
- State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences.,Department of Medicine and Therapeutics, the Chinese University of Hong Kong, Shatin, Hong Kong
| | | | - William Kk Wu
- Department of Anesthesia and Intensive Care.,State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences
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22
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Seidl K, Leemann M, Zinkernagel AS. The ArlRS two-component system is a regulator of Staphylococcus aureus-induced endothelial cell damage. Eur J Clin Microbiol Infect Dis 2017; 37:289-292. [PMID: 29177635 DOI: 10.1007/s10096-017-3130-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 10/30/2017] [Indexed: 01/23/2023]
Abstract
Staphylococcus aureus endovascular infections retain a high morbidity and mortality despite antibiotics and supportive care. The destruction of endothelial cells (ECs) is a critical step in the pathogenesis of S. aureus endovascular infections. In order to better understand S. aureus-induced EC damage, we systematically screened a collection of two-component regulatory system mutants of methicillin-resistant S. aureus (MRSA) USA300 strain JE2 for damage induction in human umbilical vein ECs (HUVECs). This screen revealed that the two-component regulatory system ArlRS is required for maximum damage: arlRS inactivation leads to a > 70% reduction in damage. In a different genetic S. aureus background (RN6390, MSSA strain) arlRS inactivation had a smaller but also significant effect on EC damage. In both strains, the reduction in EC damage was accompanied by a significant reduction in internalization. In conclusion, we determined a novel role of ArlRS in S. aureus-induced EC damage, which will help to better understand the pathogenesis of S. aureus endovascular infection.
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Affiliation(s)
- Kati Seidl
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Rämistr. 100, RAE U, 8091, Zurich, Switzerland.
| | - Michèle Leemann
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Rämistr. 100, RAE U, 8091, Zurich, Switzerland
| | - Annelies S Zinkernagel
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Rämistr. 100, RAE U, 8091, Zurich, Switzerland
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23
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Pando JM, Pfeltz RF, Cuaron JA, Nagarajan V, Mishra MN, Torres NJ, Elasri MO, Wilkinson BJ, Gustafson JE. Ethanol-induced stress response of Staphylococcus aureus. Can J Microbiol 2017; 63:745-757. [PMID: 28521110 DOI: 10.1139/cjm-2017-0221] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Transcriptional profiles of 2 unrelated clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates were analyzed following 10% (v/v) ethanol challenge (15 min), which arrested growth but did not reduce viability. Ethanol-induced stress (EIS) resulted in differential gene expression of 1091 genes, 600 common to both strains, of which 291 were upregulated. With the exception of the downregulation of genes involved with osmotic stress functions, EIS resulted in the upregulation of genes that contribute to stress response networks, notably those altered by oxidative stress, protein quality control in general, and heat shock in particular. In addition, genes involved with transcription, translation, and nucleotide biosynthesis were downregulated. relP, which encodes a small alarmone synthetase (RelP), was highly upregulated in both MRSA strains following ethanol challenge, and relP inactivation experiments indicated that this gene contributed to EIS growth arrest. A number of persistence-associated genes were also upregulated during EIS, including those that encode toxin-antitoxin systems. Overall, transcriptional profiling indicated that the MRSA investigated responded to EIS by entering a state of dormancy and by altering the expression of elements from cross protective stress response systems in an effort to protect preexisting proteins.
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Affiliation(s)
- Jasmine M Pando
- a Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA
| | - Richard F Pfeltz
- b BD Diagnostic Systems, Microbiology R&D Department, Sparks, MD 21152, USA
| | - Jesus A Cuaron
- a Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA
| | - Vijayaraj Nagarajan
- c Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Mukti N Mishra
- d Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Nathanial J Torres
- d Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Mohamed O Elasri
- c Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Brian J Wilkinson
- e Microbiology Group, School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - John E Gustafson
- a Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA.,d Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
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24
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Sugar Allocation to Metabolic Pathways is Tightly Regulated and Affects the Virulence of Streptococcus mutans. Genes (Basel) 2016; 8:genes8010011. [PMID: 28036052 PMCID: PMC5295006 DOI: 10.3390/genes8010011] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/14/2016] [Accepted: 12/21/2016] [Indexed: 02/03/2023] Open
Abstract
Bacteria take up and metabolize sugar as a carbohydrate source for survival. Most bacteria can utilize many sugars, including glucose, sucrose, and galactose, as well as amino sugars, such as glucosamine and N-acetylglucosamine. After entering the cytoplasm, the sugars are mainly allocated to the glycolysis pathway (energy production) and to various bacterial component biosynthesis pathways, including the cell wall, nucleic acids and amino acids. Sugars are also utilized to produce several virulence factors, such as capsule and lipoteichoic acid. Glutamine-fructose-6-phosphate aminotransferase (GlmS) and glucosamine-6-phosphate deaminase (NagB) have crucial roles in sugar distribution to the glycolysis pathway and to cell wall biosynthesis. In Streptococcus mutans, a cariogenic pathogen, the expression levels of glmS and nagB are coordinately regulated in response to the presence or absence of amino sugars. In addition, the disruption of this regulation affects the virulence of S. mutans. The expression of nagB and glmS is regulated by NagR in S. mutans, but the precise mechanism underlying glmS regulation is not clear. In Staphylococcus aureus and Bacillus subtilis, the mRNA of glmS has ribozyme activity and undergoes self-degradation at the mRNA level. However, there is no ribozyme activity region on glmS mRNA in S. mutans. In this review article, we summarize the sugar distribution, particularly the coordinated regulation of GlmS and NagB expression, and its relationship with the virulence of S. mutans.
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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: 139] [Impact Index Per Article: 17.4] [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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RpiRc Is a Pleiotropic Effector of Virulence Determinant Synthesis and Attenuates Pathogenicity in Staphylococcus aureus. Infect Immun 2016; 84:2031-2041. [PMID: 27113358 DOI: 10.1128/iai.00285-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 04/17/2016] [Indexed: 12/16/2022] Open
Abstract
In Staphylococcus aureus, metabolism is intimately linked with virulence determinant biosynthesis, and several metabolite-responsive regulators have been reported to mediate this linkage. S. aureus possesses at least three members of the RpiR family of transcriptional regulators. Of the three RpiR homologs, RpiRc is a potential regulator of the pentose phosphate pathway, which also regulates RNAIII levels. RNAIII is the regulatory RNA of the agr quorum-sensing system that controls virulence determinant synthesis. The effect of RpiRc on RNAIII likely involves other regulators, as the regulators that bind the RNAIII promoter have been intensely studied. To determine which regulators might bridge the gap between RpiRc and RNAIII, sarA, sigB, mgrA, and acnA mutations were introduced into an rpiRc mutant background, and the effects on RNAIII were determined. Additionally, phenotypic and genotypic differences were examined in the single and double mutant strains, and the virulence of select strains was examined using two different murine infection models. The data suggest that RpiRc affects RNAIII transcription and the synthesis of virulence determinants in concert with σ(B), SarA, and the bacterial metabolic status to negatively affect virulence.
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SpoVG Regulates Cell Wall Metabolism and Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus Strain N315. Antimicrob Agents Chemother 2016; 60:3455-61. [PMID: 27001809 DOI: 10.1128/aac.00026-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/17/2016] [Indexed: 01/07/2023] Open
Abstract
Increasing cases of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) strains in healthy individuals have raised concerns worldwide. MRSA strains are resistant to almost the entire family of β-lactam antibiotics due to the acquisition of an extra penicillin-binding protein, PBP2a. Studies have shown that spoVG is involved in oxacillin resistance, while the regulatory mechanism remains elusive. In this study, we have found that SpoVG plays a positive role in oxacillin resistance through promoting cell wall synthesis and inhibiting cell wall degradation in MRSA strain N315. Deletion of spoVG in strain N315 led to a significant decrease in oxacillin resistance and a dramatic increase in Triton X-100-induced autolytic activity simultaneously. Real-time quantitative reverse transcription-PCR revealed that the expression of 8 genes related to cell wall metabolism or oxacillin resistance was altered in the spoVG mutant. Electrophoretic mobility shift assay indicated that SpoVG can directly bind to the putative promoter regions of lytN (murein hydrolase), femA, and lytSR (the two-component system). These findings suggest a molecular mechanism in which SpoVG modulates oxacillin resistance by regulating cell wall metabolism in MRSA.
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Stk1-mediated phosphorylation stimulates the DNA-binding properties of the Staphylococcus aureus SpoVG transcriptional factor. Biochem Biophys Res Commun 2016; 473:1223-1228. [DOI: 10.1016/j.bbrc.2016.04.044] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 04/10/2016] [Indexed: 11/17/2022]
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SpoVG Is a Conserved RNA-Binding Protein That Regulates Listeria monocytogenes Lysozyme Resistance, Virulence, and Swarming Motility. mBio 2016; 7:e00240. [PMID: 27048798 PMCID: PMC4959528 DOI: 10.1128/mbio.00240-16] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
In this study, we sought to characterize the targets of the abundant Listeria monocytogenes noncoding RNA Rli31, which is required for L. monocytogenes lysozyme resistance and pathogenesis. Whole-genome sequencing of lysozyme-resistant suppressor strains identified loss-of-expression mutations in the promoter of spoVG, and deletion of spoVG rescued lysozyme sensitivity and attenuation in vivo of the rli31 mutant. SpoVG was demonstrated to be an RNA-binding protein that interacted with Rli31 in vitro. The relationship between Rli31 and SpoVG is multifaceted, as both the spoVG-encoded protein and the spoVG 5′-untranslated region interacted with Rli31. In addition, we observed that spoVG-deficient bacteria were nonmotile in soft agar and suppressor mutations that restored swarming motility were identified in the gene encoding a major RNase in Gram-positive bacteria, RNase J1. Collectively, these findings suggest that SpoVG is similar to global posttranscriptional regulators, a class of RNA-binding proteins that interact with noncoding RNA, regulate genes in concert with RNases, and control pleiotropic aspects of bacterial physiology. spoVG is widely conserved among bacteria; however, the function of this gene has remained unclear since its initial characterization in 1977. Mutation of spoVG impacts various phenotypes in Gram-positive bacteria, including methicillin resistance, capsule formation, and enzyme secretion in Staphylococcus aureus and also asymmetric cell division, hemolysin production, and sporulation in Bacillus subtilis. Here, we demonstrate that spoVG mutant strains of Listeria monocytogenes are hyper-lysozyme resistant, hypervirulent, nonmotile, and misregulate genes controlling carbon metabolism. Furthermore, we demonstrate that SpoVG is an RNA-binding protein. These findings suggest that SpoVG has a role in L. monocytogenes, and perhaps in other bacteria, as a global gene regulator. Posttranscriptional gene regulators help bacteria adapt to various environments and coordinate differing aspects of bacterial physiology. SpoVG may help the organism coordinate environmental growth and virulence to survive as a facultative pathogen.
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The degree of virulence does not necessarily affect MRSA biofilm strength and response to photodynamic therapy. Microb Pathog 2016; 91:54-60. [DOI: 10.1016/j.micpath.2015.11.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/05/2015] [Accepted: 11/09/2015] [Indexed: 12/25/2022]
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A. Elnakady Y, Chatterjee I, Bischoff M, Rohde M, Josten M, Sahl HG, Herrmann M, Müller R. Investigations to the Antibacterial Mechanism of Action of Kendomycin. PLoS One 2016; 11:e0146165. [PMID: 26795276 PMCID: PMC4721675 DOI: 10.1371/journal.pone.0146165] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Accepted: 12/14/2015] [Indexed: 11/25/2022] Open
Abstract
Purpose The emergence of bacteria that are resistant to many currently used drugs emphasizes the need to discover and develop new antibiotics that are effective against such multi-resistant strains. Kendomycin is a novel polyketide that has a unique quinone methide ansa structure and various biological properties. This compound exhibits strong antibacterial activity against Gram-negative and Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Despite the promise of kendomycinin in several therapeutic areas, its mode of action has yet to be identified. Methods In this study, we used a multidisciplinary approach to gain insight into the antibacterial mechanism of this compound. Results The antibacterial activity of kendomycin appears to be bacteriostatic rather than bactericidal. Kendomycin inhibited the growth of the MRSA strain COL at a low concentration (MIC of 5 μg/mL). Proteomic analysis and gene transcription profiling of kendomycin-treated cells indicated that this compound affected the regulation of numerous proteins and genes involved in central metabolic pathways, such as the tricarboxylic acid (TCA) cycle (SdhA) and gluconeogenesis (PckA and GapB), cell wall biosynthesis and cell division (FtsA, FtsZ, and MurAA), capsule production (Cap5A and Cap5C), bacterial programmed cell death (LrgA and CidA), the cellular stress response (ClpB, ClpC, ClpP, GroEL, DnaK, and GrpE), and oxidative stress (AhpC and KatA). Electron microscopy revealed that kendomycin strongly affected septum formation during cell division. Most kendomycin-treated cells displayed incomplete septa with abnormal morphology. Conclusions Kendomycin might directly or indirectly affect the cell division machinery, protein stability, and programmed cell death in S. aureus. Additional studies are still needed to obtain deeper insight into the mode of action of kendomycin.
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Affiliation(s)
- Yasser A. Elnakady
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Department of Pharmaceutical Biotechnology, Saarland University, Saarbrücken, Germany
- Faculty of Science, Zoology Department, King Saud University, Riyadh, Saudi Arabia
| | - Indranil Chatterjee
- Institute of Medical Microbiology and Hygiene, Saarland University, Homburg, Germany
| | - Markus Bischoff
- Institute of Medical Microbiology and Hygiene, Saarland University, Homburg, Germany
| | - Manfred Rohde
- Department of Medical Microbiology, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Michaele Josten
- Department of Medical Microbiology, Bonn University, Bonn, Germany
| | - Hans-Georg Sahl
- Department of Medical Microbiology, Bonn University, Bonn, Germany
| | - Mathias Herrmann
- Institute of Medical Microbiology and Hygiene, Saarland University, Homburg, Germany
| | - Rolf Müller
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Department of Pharmaceutical Biotechnology, Saarland University, Saarbrücken, Germany
- * E-mail:
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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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George SE, Nguyen T, Geiger T, Weidenmaier C, Lee JC, Liese J, Wolz C. Phenotypic heterogeneity and temporal expression of the capsular polysaccharide in Staphylococcus aureus. Mol Microbiol 2015; 98:1073-88. [PMID: 26303846 DOI: 10.1111/mmi.13174] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2015] [Indexed: 01/18/2023]
Abstract
Bacteria respond to ever-changing environments through several adaptive strategies. This includes mechanisms leading to a high degree of phenotypic variability within a genetically homogeneous population. In Staphylococcus aureus, the capsular polysaccharide (CP) protects against phagocytosis, but also impedes adherence to endothelial cells and/or matrix proteins. We analysed the regulation of core biosynthesis genes (capA-P) necessary for CP synthesis using single-cell assays (immunofluorescence and promoter-activity). In persistent human carriers, we found a distinct subpopulation of nasal S. aureus to be CP positive. In vitro, cap expression is also heterogeneous and strongly growth-phase dependent. We asked whether this peculiar expression pattern (earlyOff/lateHeterogen) is orchestrated by the quorum system Agr. We show that the Agr-driven effector molecule RNAIII promotes cap expression largely via inactivation of the repressor Rot. High NaCl, deletion of CodY or Sae also resulted in higher cap expression but did not change the earlyOFF/lateHeterogen expression pattern. Activity of the quorum system itself is largely homogenous and does not account for the observed heterogeneity of cap expression or the strictly growth phase dependent expression. Our findings are in contrast to the prevailing view that quorum sensing is the main driving force for virulence gene expression when bacterial cell densities increase.
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Affiliation(s)
- Shilpa E George
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Tran Nguyen
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany.,Centre for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany
| | - Tobias Geiger
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Christopher Weidenmaier
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Jean C Lee
- Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Jan Liese
- 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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RbsR Activates Capsule but Represses the rbsUDK Operon in Staphylococcus aureus. J Bacteriol 2015; 197:3666-75. [PMID: 26350136 DOI: 10.1128/jb.00640-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 09/02/2015] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Staphylococcus aureus capsule is an important virulence factor that is regulated by a large number of regulators. Capsule genes are expressed from a major promoter upstream of the cap operon. A 10-bp inverted repeat (IR) located 13 bp upstream of the -35 region of the promoter was previously shown to affect capsule gene transcription. However, little is known about transcriptional activation of the cap promoter. To search for potential proteins which directly interact with the cap promoter region (Pcap), we directly analyzed the proteins interacting with the Pcap DNA fragment from shifted gel bands identified by electrophoretic mobility shift assay. One of these regulators, RbsR, was further characterized and found to positively regulate cap gene expression by specifically binding to the cap promoter region. Footprinting analyses showed that RbsR protected a DNA region encompassing the 10-bp IR. Our results further showed that rbsR was directly controlled by SigB and that RbsR was a repressor of the rbsUDK operon, involved in ribose uptake and phosphorylation. The repression of rbsUDK by RbsR could be derepressed by D-ribose. However, D-ribose did not affect RbsR activation of capsule. IMPORTANCE Staphylococcus aureus is an important human pathogen which produces a large number of virulence factors. We have been using capsule as a model virulence factor to study virulence regulation. Although many capsule regulators have been identified, the mechanism of regulation of most of these regulators is unknown. We show here that RbsR activates capsule by direct promoter binding and that SigB is required for the expression of rbsR. These results define a new pathway wherein SigB activates capsule through RbsR. Our results further demonstrate that RbsR inhibits the rbs operon involved in ribose utilization, thereby providing an example of coregulation of metabolism and virulence in S. aureus. Thus, this study further advances our understanding of staphylococcal virulence regulation.
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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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Whiteley AT, Pollock AJ, Portnoy DA. The PAMP c-di-AMP Is Essential for Listeria monocytogenes Growth in Rich but Not Minimal Media due to a Toxic Increase in (p)ppGpp. [corrected]. Cell Host Microbe 2015; 17:788-98. [PMID: 26028365 PMCID: PMC4469362 DOI: 10.1016/j.chom.2015.05.006] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 03/05/2015] [Accepted: 03/31/2015] [Indexed: 12/20/2022]
Abstract
Cyclic di-adenosine monophosphate (c-di-AMP) is a widely distributed second messenger that appears to be essential in multiple bacterial species, including the Gram-positive facultative intracellular pathogen Listeria monocytogenes. In this study, the only L. monocytogenes diadenylate cyclase gene, dacA, was deleted using a Cre-lox system activated during infection of cultured macrophages. All ΔdacA strains recovered from infected cells harbored one or more suppressor mutations that allowed growth in the absence of c-di-AMP. Suppressor mutations in the synthase domain of the bi-functional (p)ppGpp synthase/hydrolase led to reduced (p)ppGpp levels. A genetic assay confirmed that dacA was essential in wild-type but not strains lacking all three (p)ppGpp synthases. Further genetic analysis suggested that c-di-AMP was essential because accumulated (p)ppGpp altered GTP concentrations, thereby inactivating the pleiotropic transcriptional regulator CodY. We propose that c-di-AMP is conditionally essential for metabolic changes that occur in growth in rich medium and host cells but not minimal medium.
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Affiliation(s)
- Aaron T Whiteley
- Graduate Group in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Alex J Pollock
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Daniel A Portnoy
- Graduate Group in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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Weidenmaier C, Lee JC. Structure and Function of Surface Polysaccharides of Staphylococcus aureus. Curr Top Microbiol Immunol 2015; 409:57-93. [PMID: 26728067 DOI: 10.1007/82_2015_5018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The major surface polysaccharides of Staphylococcus aureus include the capsular polysaccharide (CP), cell wall teichoic acid (WTA), and polysaccharide intercellular adhesin/poly-β(1-6)-N-acetylglucosamine (PIA/PNAG). These glycopolymers are important components of the staphylococcal cell envelope, but none of them is essential to S. aureus viability and growth in vitro. The overall biosynthetic pathways of CP, WTA, and PIA/PNAG have been elucidated, and the functions of most of the biosynthetic enzymes have been demonstrated. Because S. aureus CP and WTA (but not PIA/PNAG) utilize a common cell membrane lipid carrier (undecaprenyl-phosphate) that is shared by the peptidoglycan biosynthesis pathway, there is evidence that these processes are highly integrated and temporally regulated. Regulatory elements that control glycopolymer biosynthesis have been described, but the cross talk that orchestrates the biosynthetic pathways of these three polysaccharides remains largely elusive. CP, WTA, and PIA/PNAG each play distinct roles in S. aureus colonization and the pathogenesis of staphylococcal infection. However, they each promote bacterial evasion of the host immune defences, and WTA is being explored as a target for antimicrobial therapeutics. All the three glycopolymers are viable targets for immunotherapy, and each (conjugated to a carrier protein) is under evaluation for inclusion in a multivalent S. aureus vaccine. Future research findings that increase our understanding of these surface polysaccharides, how the bacterial cell regulates their expression, and their biological functions will likely reveal new approaches to controlling this important bacterial pathogen.
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Affiliation(s)
- Christopher Weidenmaier
- Interfaculty Institute for Microbiology and Infection Medicine Tübingen, University of Tübingen and German Center for Infection Research, Tübingen, Germany
| | - Jean C Lee
- Division of Infectious Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
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The Role of Two-Component Signal Transduction Systems in Staphylococcus aureus Virulence Regulation. Curr Top Microbiol Immunol 2015; 409:145-198. [PMID: 26728068 DOI: 10.1007/82_2015_5019] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Staphylococcus aureus is a versatile, opportunistic human pathogen that can asymptomatically colonize a human host but can also cause a variety of cutaneous and systemic infections. The ability of S. aureus to adapt to such diverse environments is reflected in the presence of complex regulatory networks fine-tuning metabolic and virulence gene expression. One of the most widely distributed mechanisms is the two-component signal transduction system (TCS) which allows a pathogen to alter its gene expression profile in response to environmental stimuli. The simpler TCSs consist of only a transmembrane histidine kinase (HK) and a cytosolic response regulator. S. aureus encodes a total of 16 conserved pairs of TCSs that are involved in diverse signalling cascades ranging from global virulence gene regulation (e.g. quorum sensing by the Agr system), the bacterial response to antimicrobial agents, cell wall metabolism, respiration and nutrient sensing. These regulatory circuits are often interconnected and affect each other's expression, thus fine-tuning staphylococcal gene regulation. This manuscript gives an overview of the current knowledge of staphylococcal environmental sensing by TCS and its influence on virulence gene expression and virulence itself. Understanding bacterial gene regulation by TCS can give major insights into staphylococcal pathogenicity and has important implications for knowledge-based drug design and vaccine formulation.
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Gustafson JE, Muthaiyan A, Dupre JM, Ricke SC. WITHDRAWN: Staphylococcus aureus and understanding the factors that impact enterotoxin production in foods: A review. Food Control 2014. [DOI: 10.1016/j.foodcont.2014.10.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Wu Y, Liu J, Jiang J, Hu J, Xu T, Wang J, Qu D. Role of the two-component regulatory system arlRS in ica operon and aap positive but non-biofilm-forming Staphylococcus epidermidis isolates from hospitalized patients. Microb Pathog 2014; 76:89-98. [PMID: 25263000 DOI: 10.1016/j.micpath.2014.09.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/21/2014] [Accepted: 09/24/2014] [Indexed: 10/24/2022]
Abstract
The ica operon and aap gene are important factors for Staphylococcus epidermidis biofilm formation. However, we found 15 out of 101 S. epidermidis strains isolated from patients had both the ica operon and the aap gene in the genome but could not form biofilms (ica(+)aap(+)/BF(-) isolates). Compared with standard strain RP62A, the 15 ica(+)aap(+)/BF(-) isolates had similar growth curves and initial attachment abilities, but had much lower apparent transcription levels of the icaA gene and significantly less production of polysaccharide intercellular adhesion (PIA). Furthermore, the expression of accumulation-associated protein in ica(+)aap(+)/BF(-) isolates was much weaker than in RP62A. The mRNA levels of icaADBC transcription-related regulatory genes, including icaR, sarA, rsbU, srrA, arlRS and luxS, were measured in the 15 ica(+)aap(+)/BF(-) clinical isolates. The mRNA levels of arlR and rsbU in all of the ica(+)aap(+)/BF(-) isolates were lower than in RP62A at 4 h. At 10 h, 14/15 of the isolates showed lower mRNA levels of arlR and rsbU than shown by RP62A. However, expression of sarA, luxS, srrA and icaR varied in different ica(+)aap(+)/BF(-) isolates. To further investigate the role of arlRS in biofilm formation, we analyzed icaA, sarA and rsbU transcription, PIA synthesis, Aap expression and biofilm formation in an arlRS deletion mutant of S. epidermidis strain 1457 and all were much less than in the wild type strain. This is consistent with the hypothesis that ArlRS may play an important role in regulating biofilm formation by the ica(+)aap(+)/BF(-)S. epidermidis clinical isolates and operate via both ica-dependent and Aap-dependent pathways.
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Affiliation(s)
- Yang Wu
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China
| | - Jingran Liu
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China
| | - Juan Jiang
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China
| | - Jian Hu
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China
| | - Tao Xu
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China
| | - Jiaxue Wang
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China
| | - Di Qu
- Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, PR China.
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Schröder W, Bernhardt J, Marincola G, Klein-Hitpass L, Herbig A, Krupp G, Nieselt K, Wolz C. Altering gene expression by aminocoumarins: the role of DNA supercoiling in Staphylococcus aureus. BMC Genomics 2014; 15:291. [PMID: 24734910 PMCID: PMC4023603 DOI: 10.1186/1471-2164-15-291] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 03/17/2014] [Indexed: 11/29/2022] Open
Abstract
Background It has been shown previously that aminocoumarin antibiotics such as novobiocin lead to immediate downregulation of recA expression and thereby inhibit the SOS response, mutation frequency and recombination capacity in Staphylococcus aureus. Aminocoumarins function by inhibiting the ATPase activity of DNA gyrase subunit B with a severe impact on DNA supercoiling. Results Here, we have analysed the global impact of the DNA relaxing agent novobiocin on gene expression in S. aureus. Using a novobiocin-resistant mutant, it became evident that the change in recA expression is due to gyrase inhibition. Microarray analysis and northern blot hybridisation revealed that the expression levels of a distinct set of genes were increased (e.g., recF-gyrB-gyrA, the rib operon and the ure operon) or decreased (e.g., arlRS, recA, lukA, hlgC and fnbA) by novobiocin. The two-component ArlRS system was previously found to decrease the level of supercoiling in S. aureus. Thus, downregulation of arlRS might partially compensate for the relaxing effect of novobiocin. Global analysis and gene mapping of supercoiling-sensitive genes did not provide any indication that they are clustered in the genome. Promoter fusion assays confirmed that the responsiveness of a given gene is intrinsic to the promoter region but independent of the chromosomal location. Conclusions The results indicate that the molecular properties of a given promoter, rather than the chromosomal topology, dictate the responsiveness to changes in supercoiling in the pathogen Staphylococcus aureus.
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Affiliation(s)
| | | | | | | | | | | | | | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany.
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Romilly C, Lays C, Tomasini A, Caldelari I, Benito Y, Hammann P, Geissmann T, Boisset S, Romby P, Vandenesch F. A non-coding RNA promotes bacterial persistence and decreases virulence by regulating a regulator in Staphylococcus aureus. PLoS Pathog 2014; 10:e1003979. [PMID: 24651379 PMCID: PMC3961350 DOI: 10.1371/journal.ppat.1003979] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 01/21/2014] [Indexed: 11/19/2022] Open
Abstract
Staphylococcus aureus produces a high number of RNAs for which the functions are poorly understood. Several non-coding RNAs carry a C-rich sequence suggesting that they regulate mRNAs at the post-transcriptional level. We demonstrate that the Sigma B-dependent RsaA RNA represses the synthesis of the global transcriptional regulator MgrA by forming an imperfect duplex with the Shine and Dalgarno sequence and a loop-loop interaction within the coding region of the target mRNA. These two recognition sites are required for translation repression. Consequently, RsaA causes enhanced production of biofilm and a decreased synthesis of capsule formation in several strain backgrounds. These phenotypes led to a decreased protection of S. aureus against opsonophagocytic killing by polymorphonuclear leukocytes compared to the mutant strains lacking RsaA. Mice animal models showed that RsaA attenuates the severity of acute systemic infections and enhances chronic catheter infection. RsaA takes part in a regulatory network that contributes to the complex interactions of S. aureus with the host immune system to moderate invasiveness and favour chronic infections. It is the first example of a conserved small RNA in S. aureus functioning as a virulence suppressor of acute infections. Because S. aureus is essentially a human commensal, we propose that RsaA has been positively selected through evolution to support commensalism and saprophytic interactions with the host. Staphylococcus aureus is a commensal and an opportunistic pathogen that causes a large range of community and hospital-acquired infections. The bacteria produce an array of virulence factors, the expression of which is regulated by a set of regulators including proteins and RNAs. In recent years, a large number of small non-coding RNAs encoded by the S. aureus genome have been identified but determination of their function is still lagging behind. This study shows that RsaA, a staphylococcal conserved non-coding RNA, operates at the post-transcriptional level by repressing the translation of the master regulatory protein MgrA. The repression is based on a direct interaction of RsaA with the ribosome binding site of mgrA mRNA. Through MgrA regulation, RsaA activates biofilm formation and inhibits capsule synthesis. Using appropriate animal models, we showed that RsaA acts as a suppressor of virulence because the deletion of its gene increases the invasiveness of S. aureus in the mice sepsis model. RsaA is thus part of complex regulatory network that modify the interactions of S. aureus with the eukaryotic immune system. These findings illustrate how small RNAs can have a major impact in bacterial biology.
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Affiliation(s)
- Cédric Romilly
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Claire Lays
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
| | - Arnaud Tomasini
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Isabelle Caldelari
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Yvonne Benito
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
- Hospices Civils de Lyon, Lyon, France
| | | | - Thomas Geissmann
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
| | - Sandrine Boisset
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
- Hospices Civils de Lyon, Lyon, France
| | - Pascale Romby
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
- * E-mail: (PR); (FV)
| | - François Vandenesch
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
- Hospices Civils de Lyon, Lyon, France
- * E-mail: (PR); (FV)
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Eyraud A, Tattevin P, Chabelskaya S, Felden B. A small RNA controls a protein regulator involved in antibiotic resistance in Staphylococcus aureus. Nucleic Acids Res 2014; 42:4892-905. [PMID: 24557948 PMCID: PMC4005690 DOI: 10.1093/nar/gku149] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The emergence of Staphylococcus aureus strains that are resistant to glycopeptides has led to alarming scenarios where serious staphylococcal infections cannot be treated. The bacterium expresses many small regulatory RNAs (sRNAs) that have unknown biological functions for the most part. Here we show that an S. aureus sRNA, SprX (alias RsaOR), shapes bacterial resistance to glycopeptides, the invaluable treatments for Methicillin-resistant staphylococcal infections. Modifying SprX expression levels influences Vancomycin and Teicoplanin glycopeptide resistance. Comparative proteomic studies have identified that SprX specifically downregulates stage V sporulation protein G, SpoVG. SpoVG is produced from the yabJ-spoVG operon and contributes to S. aureus glycopeptide resistance. SprX negatively regulates SpoVG expression by direct antisense pairings at the internal translation initiation signals of the second operon gene, without modifying bicistronic mRNA expression levels or affecting YabJ translation. The SprX and yabJ-spoVG mRNA domains involved in the interaction have been identified, highlighting the importance of a CU-rich loop of SprX in the control of SpoVG expression. We have shown that SpoVG might not be the unique SprX target involved in the glycopeptide resistance and demonstrated that the regulation of glycopeptide sensitivity involves the CU-rich domain of SprX. Here we report the case of a sRNA influencing antibiotic resistance of a major human pathogen.
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Affiliation(s)
- Alex Eyraud
- Université de Rennes I, Inserm U835, Upres EA2311, Biochimie Pharmaceutique, 2 avenue du Prof. Léon Bernard, 35043 Rennes, France
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Trapping and identification of cellular substrates of the Staphylococcus aureus ClpC chaperone. J Bacteriol 2013; 195:4506-16. [PMID: 23913326 DOI: 10.1128/jb.00758-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
ClpC is an ATP-dependent Hsp100/Clp chaperone involved in protein quality control in low-GC Gram-positive bacteria. Previously, we found that ClpC affected the expression of a large number of genes, including capsule genes in Staphylococcus aureus. Here we constructed a His-tagged ClpC variant (ClpC(trap)) with mutations within the Walker B motifs to identify the direct substrates of ClpC by copurification with ClpC(trap) followed by gel electrophoresis combined with liquid chromatography-tandem mass spectrometry proteomics. We identified a total of 103 proteins that are potential substrates of ClpC in strain Newman. The direct protein-protein interaction of ClpC with a subset of the captured proteins was verified in a bacterial two-hybrid system. The captured proteins could be grouped into various functional categories, but most were related to proteins involved in the stress response. Several known ClpC substrates were captured, including ClpP, TrfA/MecA, ClpB, DnaK, DnaJ, GroL, RecA, and CodY, supporting the validity of our approach. Our results also revealed many new ClpC substrates, including AgrA, CcpA, RsbW, MurG, FtsA, SrtA, Rex, Atl, ClfA, and SbcC. Analysis of capsule production showed that three of the captured proteins, which were not previously known to be transcriptional regulators, did affect capsule production.
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Jutras BL, Chenail AM, Rowland CL, Carroll D, Miller MC, Bykowski T, Stevenson B. Eubacterial SpoVG homologs constitute a new family of site-specific DNA-binding proteins. PLoS One 2013; 8:e66683. [PMID: 23818957 PMCID: PMC3688583 DOI: 10.1371/journal.pone.0066683] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 05/09/2013] [Indexed: 01/06/2023] Open
Abstract
A site-specific DNA-binding protein was purified from Borrelia burgdorferi cytoplasmic extracts, and determined to be a member of the highly conserved SpoVG family. This is the first time a function has been attributed to any of these ubiquitous bacterial proteins. Further investigations into SpoVG orthologues indicated that the Staphylococcus aureus protein also binds DNA, but interacts preferentially with a distinct nucleic acid sequence. Site-directed mutagenesis and domain swapping between the S. aureus and B. burgdorferi proteins identified that a 6-residue stretch of the SpoVG α-helix contributes to DNA sequence specificity. Two additional, highly conserved amino acid residues on an adjacent β-sheet are essential for DNA-binding, apparently by contacts with the DNA phosphate backbone. Results of these studies thus identified a novel family of bacterial DNA-binding proteins, developed a model of SpoVG-DNA interactions, and provide direction for future functional studies on these wide-spread proteins.
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Affiliation(s)
- Brandon L. Jutras
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Alicia M. Chenail
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Christi L. Rowland
- Department of Agricultural Sciences, University of Kentucky College of Agriculture, Lexington, Kentucky, United States of America
| | - Dustin Carroll
- Graduate Center for Toxicology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - M. Clarke Miller
- Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Tomasz Bykowski
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Brian Stevenson
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- * E-mail:
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Beceiro A, Tomás M, Bou G. Antimicrobial resistance and virulence: a successful or deleterious association in the bacterial world? Clin Microbiol Rev 2013; 26:185-230. [PMID: 23554414 PMCID: PMC3623377 DOI: 10.1128/cmr.00059-12] [Citation(s) in RCA: 626] [Impact Index Per Article: 56.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hosts and bacteria have coevolved over millions of years, during which pathogenic bacteria have modified their virulence mechanisms to adapt to host defense systems. Although the spread of pathogens has been hindered by the discovery and widespread use of antimicrobial agents, antimicrobial resistance has increased globally. The emergence of resistant bacteria has accelerated in recent years, mainly as a result of increased selective pressure. However, although antimicrobial resistance and bacterial virulence have developed on different timescales, they share some common characteristics. This review considers how bacterial virulence and fitness are affected by antibiotic resistance and also how the relationship between virulence and resistance is affected by different genetic mechanisms (e.g., coselection and compensatory mutations) and by the most prevalent global responses. The interplay between these factors and the associated biological costs depend on four main factors: the bacterial species involved, virulence and resistance mechanisms, the ecological niche, and the host. The development of new strategies involving new antimicrobials or nonantimicrobial compounds and of novel diagnostic methods that focus on high-risk clones and rapid tests to detect virulence markers may help to resolve the increasing problem of the association between virulence and resistance, which is becoming more beneficial for pathogenic bacteria.
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Junecko JM, Zielinska AK, Mrak LN, Ryan DC, Graham JW, Smeltzer MS, Lee CY. Transcribing virulence in Staphylococcus aureus. World J Clin Infect Dis 2012; 2:63-76. [DOI: 10.5495/wjcid.v2.i4.63] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is an important human pathogen capable of causing a diverse range of infections. Once regarded as an opportunistic pathogen causing primarily nosocomial infections, recent years have seen the emergence of S. aureus strains capable of causing serious infection even in otherwise healthy human hosts. There has been much debate about whether this transition is a function of unique genotypic characteristics or differences in the expression of conserved virulence factors, but irrespective of this debate it is clear that the ability of S. aureus to cause infection in all of its diverse forms is heavily influenced by its ability to modulate gene expression in response to changing conditions within the human host. Indeed, the S. aureus genome encodes more than 100 transcriptional regulators that modulate the production of virulence factors either directly via interactions with cis elements associated with genes encoding virulence factors or indirectly through their complex interactions with each other. The goal of this review is to summarize recent work describing these regulators and their contribution to defining S. aureus as a human pathogen.
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Chaffin DO, Taylor D, Skerrett SJ, Rubens CE. Changes in the Staphylococcus aureus transcriptome during early adaptation to the lung. PLoS One 2012; 7:e41329. [PMID: 22876285 PMCID: PMC3410880 DOI: 10.1371/journal.pone.0041329] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 06/25/2012] [Indexed: 01/04/2023] Open
Abstract
Staphylococcus aureus is a common inhabitant of the human nasopharynx. It is also a cause of life-threatening illness, producing a potent array of virulence factors that enable survival in normally sterile sites. The transformation of S. aureus from commensal to pathogen is poorly understood. We analyzed S. aureus gene expression during adaptation to the lung using a mouse model of S. aureus pneumonia. Bacteria were isolated by bronchoalveolar lavage after residence in vivo for up to 6 hours. S. aureus in vivo RNA transcription was compared by microarray to that of shake flask grown stationary phase and early exponential phase cells. Compared to in vitro conditions, the in vivo transcriptome was dramatically altered within 30 minutes. Expression of central metabolic pathways changed significantly in response to the lung environment. Gluconeogenesis (fbs, pckA) was down regulated, as was TCA cycle and fermentation pathway gene expression. Genes associated with amino acid synthesis, RNA translation and nitrate respiration were upregulated, indicative of a highly active metabolic state during the first 6 hours in the lung. Virulence factors regulated by agr were down regulated in vivo and in early exponential phase compared to stationary phase cells. Over time in vivo, expression of ahpCF, involved in H2O2 scavenging, and uspA, which encodes a universal stress regulator, increased. Transcription of leukotoxic α and β-type phenol-soluble modulins psmα1-4 and psmβ1-2 increased 13 and 8-fold respectively; hld mRNA, encoding δ-hemolysin, was increased 9-fold. These were the only toxins to be significantly upregulated in vivo. These data provide the first complete survey of the S. aureus transcriptome response to the mammalian airway. The results present intriguing contrasts with previous work in other in vitro and in vivo models and provide novel insights into the adaptive and temporal response of S. aureus early in the pathogenesis of pneumonia.
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Affiliation(s)
- Donald O. Chaffin
- Seattle Children’s Hospital Research Institute, Seattle, Washington, United States of America
| | - Destry Taylor
- University of Washington, Seattle, Washington, United States of America
| | - Shawn J. Skerrett
- University of Washington, Seattle, Washington, United States of America
| | - Craig E. Rubens
- Seattle Children’s Hospital Research Institute, Seattle, Washington, United States of America
- University of Washington, Seattle, Washington, United States of America
- * E-mail:
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Wu Y, Wang J, Xu T, Liu J, Yu W, Lou Q, Zhu T, He N, Ben H, Hu J, Götz F, Qu D. The two-component signal transduction system ArlRS regulates Staphylococcus epidermidis biofilm formation in an ica-dependent manner. PLoS One 2012; 7:e40041. [PMID: 22848368 PMCID: PMC3407220 DOI: 10.1371/journal.pone.0040041] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 05/31/2012] [Indexed: 12/30/2022] Open
Abstract
Due to its ability to form biofilms on medical devices, Staphylococcus epidermidis has emerged as a major pathogen of nosocomial infections. In this study, we investigated the role of the two-component signal transduction system ArlRS in regulating S. epidermidis biofilm formation. An ArlRS-deficient mutant, WW06, was constructed using S. epidermidis strain 1457 as a parental strain. Although the growth curve of WW06 was similar to that of SE1457, the mutant strain was unable to form biofilms in vitro. In a rabbit subcutaneous infection model, sterile disks made of polymeric materials were implanted subcutaneously followed with inoculation of WW06 or SE1457. The viable bacteria cells of WW06 recovered from biofilms on the embedded disks were much lower than that of SE1457. Complementation of arlRS genes expression from plasmid in WW06 restored biofilm-forming phenotype both in vivo and in vitro. WW06 maintained the ability to undergo initial attachment. Transcription levels of several genes involved in biofilm formation, including icaADBC, sigB, and sarA, were decreased in WW06, compared to SE1457; and icaR expression was increased in WW06, detected by real-time reverse-transcription PCR. The biofilm-forming phenotype was restored by overexpressing icaADBC in WW06 but not by overexpressing sigB, indicating that ArlRS regulates biofilm formation through the regulation of icaADBC. Gel shift assay showed that ArlR can bind to the promoter region of the ica operon. In conclusion, ArlRS regulates S. epidermidis biofilm formation in an ica-dependent manner, distinct from its role in S. aureus.
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Affiliation(s)
- Yang Wu
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
| | - Jiaxue Wang
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
| | - Tao Xu
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
| | - Jingran Liu
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
| | - Wenqi Yu
- Microbial Genetics, University of Tübingen, Tübingen, Germany
| | - Qiang Lou
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
| | - Tao Zhu
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
| | - Nianan He
- Department of Ultrasound, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Haijing Ben
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
| | - Jian Hu
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
| | - Friedrich Götz
- Microbial Genetics, University of Tübingen, Tübingen, Germany
| | - Di Qu
- Key Laboratory of Medical Molecular Virology of the Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai, P.R. China
- * E-mail:
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50
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Schulthess B, Bloes DA, Berger-Bächi B. Opposing roles of σB and σB-controlled SpoVG in the global regulation of esxA in Staphylococcus aureus. BMC Microbiol 2012; 12:17. [PMID: 22272815 PMCID: PMC3313859 DOI: 10.1186/1471-2180-12-17] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Accepted: 01/24/2012] [Indexed: 01/12/2023] Open
Abstract
Background The production of virulence factors in Staphylococcus aureus is tightly controlled by a complex web of interacting regulators. EsxA is one of the virulence factors that are excreted by the specialized, type VII-like Ess secretion system of S. aureus. The esxA gene is part of the σB-dependent SpoVG subregulon. However, the mode of action of SpoVG and its impact on other global regulators acting on esxA transcription is as yet unknown. Results We demonstrate that the transcription of esxA is controlled by a regulatory cascade involving downstream σB-dependent regulatory elements, including the staphylococcal accessory regulator SarA, the ArlRS two-component system and SpoVG. The esxA gene, preceding the ess gene cluster, was shown to form a monocistronic transcript that is driven by a σA promoter, whereas a putative σB promoter identified upstream of the σA promoter was shown to be inactive. Transcription of esxA was strongly upregulated upon either sarA or sigB inactivation, but decreased in agr, arlR and spoVG single mutants, suggesting that agr, ArlR and SpoVG are able to increase esxA transcription and relieve the repressing effect of the σB-controlled SarA on esxA. Conclusion SpoVG is a σB-dependent element that fine-tunes the expression of esxA by counteracting the σB-induced repressing activity of the transcriptional regulator SarA and activates esxA transcription.
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Affiliation(s)
- Bettina Schulthess
- Institute of Medical Microbiology, University of Zurich, Gloriastrasse 32, 8006 Zurich, Switzerland.
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