scholarly journals Phosphorylation of MgrA and Its Effect on Expression of the NorA and NorB Efflux Pumps of Staphylococcus aureus

2010 ◽  
Vol 192 (10) ◽  
pp. 2525-2534 ◽  
Author(s):  
Que Chi Truong-Bolduc ◽  
David C. Hooper
Keyword(s):  
Staphylococcus Aureus ◽  
Multidrug Resistance ◽  
Virulence Factors ◽  
Double Mutant ◽  
Efflux Pumps ◽  
Efflux Transporters ◽  
Global Regulator ◽  
Binding Assays ◽  
Genes Encoding ◽  
Gel Shift

ABSTRACT MgrA is a global regulator in Staphylococcus aureus that controls the expression of diverse genes encoding virulence factors and multidrug resistance (MDR) efflux transporters. We identified pknB, which encodes the (Ser/Thr) kinase PknB, in the S. aureus genome. PknB was able to autophosphorylate as well as phosphorylate purified MgrA. We demonstrated that rsbU, which encodes a Ser/Thr phosphatase and is involved in the activation of the SigB regulon, was able to dephosphorylate MgrA-P but not PknB-P. Serines 110 and 113 of MgrA were found to be phosphorylated, and Ala substitutions at these positions resulted in reductions in the level of phosphorylation of MgrA. DNA gel shift binding assays using norA and norB promoters showed that MgrA-P was able to bind the norB promoter but not the norA promoter, a pattern which was the reverse of that for unphosphorylated MgrA. The double mutant MgrAS110A-S113A bound to the norA promoter but not the norB promoter. The double mutant led to a 2-fold decrease in norA transcripts and a 2-fold decrease in the MICs of norfloxacin and ciprofloxacin in strain RN6390. Thus, phosphorylation of MgrA results in loss of binding to the norA promoter, but with a gain of the ability to bind the norB promoter. Loss of the ability to phosphorylate MgrA by Ala substitution resulted in increased repression of norA expression and in reductions in susceptibilities to NorA substrates.

scholarly journals The purine biosynthesis regulator PurR moonlights as a virulence regulator in Staphylococcus aureus

2019 ◽  
Vol 116 (27) ◽  
pp. 13563-13572 ◽  
Author(s):  
William E. Sause ◽  
Divya Balasubramanian ◽  
Irnov Irnov ◽  
Richard Copin ◽  
Mitchell J. Sullivan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Ex Vivo ◽  
Purine Biosynthesis ◽  
In Vivo Studies ◽  
Human Neutrophils ◽  
Infection Models ◽  
Genes Encoding ◽  
Virulence Regulator

The pathogen Staphylococcus aureus colonizes and infects a variety of different sites within the human body. To adapt to these different environments, S. aureus relies on a complex and finely tuned regulatory network. While some of these networks have been well-elucidated, the functions of more than 50% of the transcriptional regulators in S. aureus remain unexplored. Here, we assess the contribution of the LacI family of metabolic regulators to staphylococcal virulence. We found that inactivating the purine biosynthesis regulator purR resulted in a strain that was acutely virulent in bloodstream infection models in mice and in ex vivo models using primary human neutrophils. Remarkably, these enhanced pathogenic traits are independent of purine biosynthesis, as the purR mutant was still highly virulent in the presence of mutations that disrupt PurR’s canonical role. Through the use of transcriptomics coupled with proteomics, we revealed that a number of virulence factors are differentially regulated in the absence of purR. Indeed, we demonstrate that PurR directly binds to the promoters of genes encoding virulence factors and to master regulators of virulence. These results guided us into further ex vivo and in vivo studies, where we discovered that S. aureus toxins drive the death of human phagocytes and mice, whereas the surface adhesin FnbA contributes to the increased bacterial burden observed in the purR mutant. Thus, S. aureus repurposes a metabolic regulator to directly control the expression of virulence factors, and by doing so, tempers its pathogenesis.

scholarly journals Prevalence of genes encoding extracellular virulence factors among meticillin-resistant Staphylococcus aureus isolates from the University Hospital, Olomouc, Czech Republic

2008 ◽  
Vol 57 (4) ◽  
pp. 403-410 ◽  
Author(s):  
P. Sauer ◽  
J. Síla ◽  
T. Štosová ◽  
R. Večeřová ◽  
P. Hejnar ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Czech Republic ◽  
Virulence Factors ◽  
Virulence Factor ◽  
Antibiotic Susceptibility ◽  
University Hospital ◽  
Virulence Determinants ◽  
Virulence Markers ◽  
Genes Encoding ◽  
The University

A rather fast and complicated progression of an infection caused by some strains of Staphylococcus aureus could be associated with the expression and co-action of virulence factor complexes in these strains. This study screened the antibiotic susceptibility and prevalence of virulence markers in isolates of meticillin-resistant S. aureus (MRSA) obtained from patients hospitalized at the University Hospital in Olomouc, Czech Republic. A total of 100 isolates was screened for 13 genes encoding extracellular virulence determinants (tst, pvl, eta, etb, sea, seb, sec, sed, see, seg, seh, sei and sej) and for their distribution in sample types. Eighty-nine isolates were positive for at least one of the genes. Genes for etb, pvl, see and seh were not detected in any of the MRSA isolates. No statistically significant differences in the occurrence of the determinants studied among sample types were found.

scholarly journals Transcriptional Profiling of Target of RNAIII-Activating Protein, a Master Regulator of Staphylococcal Virulence

2005 ◽  
Vol 73 (10) ◽  
pp. 6220-6228 ◽  
Author(s):  
Moshe Korem ◽  
Yael Gov ◽  
Madanahally D. Kiran ◽  
Naomi Balaban
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Transcriptional Profiling ◽  
Protein A ◽  
Cell Communication ◽  
Global Regulator ◽  
Positive Bacterium ◽  
Master Regulator ◽  
Expression Of Genes ◽  
Histidine Phosphorylation

ABSTRACT Staphylococcus aureus is a gram-positive bacterium that is part of the normal healthy flora but that can become virulent and cause infections by producing biofilms and toxins. The production of virulence factors is regulated by cell-cell communication (quorum sensing) through the histidine phosphorylation of target of RNAIII-activating protein (TRAP), which is a 21-kDa protein that is highly conserved among staphylococci. Using microarray analysis, we show here that the expression and phosphorylation of TRAP upregulate the expression of most, if not all, toxins known to date, as well as their global regulator agr. In addition, we show here that the expression and phosphorylation of TRAP are also necessary for the expression of genes known to be necessary for the survival of the bacteria in a biofilm, like arc, pyr, and ure. TRAP is thus demonstrated to be a master regulator of staphylococcal pathogenesis.

scholarly journals Going through phages: A Computational approach to Revealing the role of prophage in Staphylococcus aureus

2021 ◽  
Author(s):  
Tyrome Steven Sweet ◽  
Suzanne Sindi ◽  
Mark Sistrom
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Genome Evolution ◽  
Virulence Factors ◽  
Rapid Growth ◽  
Computational Approach ◽  
Computational Pipeline ◽  
Genes Encoding

Prophages have important roles in virulence, antibiotic resistance and genome evolution in Staphylococcus aureus. Rapid growth in the number of sequenced S. aureus genomes allows for an investigation of prophage sequences in S. aureus at an unprecedented scale. We developed a computational pipeline to detect and analyze prophage sequences in nearly 10,011 S. aureus genomes, discovering thousands of putative prophage sequences with genes encoding virulence factors and antibiotic resistance.

scholarly journals Interactions between staphylococcal enterotoxins A and D and superantigen-like proteins 1 and 5 for predicting methicillin and multidrug resistance profiles among Staphylococcus aureus ocular isolates

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254519
Author(s):  
Min Lu ◽  
Jean-Marie Parel ◽  
Darlene Miller
Keyword(s):  
Machine Learning ◽  
Staphylococcus Aureus ◽  
Multidrug Resistance ◽  
Virulence Factors ◽  
Phenotypic Expression ◽  
Multidrug Resistant ◽  
Machine Learning Techniques ◽  
Strong Interactions ◽  
Antibiotics Resistance ◽  
Gene Profiles

Background Methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) S. aureus strains are well recognized as posing substantial problems in treating ocular infections. S. aureus has a vast array of virulence factors, including superantigens and enterotoxins. Their interactions and ability to signal antibiotics resistance have not been explored. Objectives To predict the relationship between superantigens and methicillin and multidrug resistance among S. aureus ocular isolates. Methods We used a DNA microarray to characterize the enterotoxin and superantigen gene profiles of 98 S. aureus isolates collected from common ocular sources. The outcomes contained phenotypic and genotypic expressions of MRSA. We also included the MDR status as an outcome, categorized as resistance to three or more drugs, including oxacillin, penicillin, erythromycin, clindamycin, moxifloxacin, tetracycline, trimethoprim-sulfamethoxazole and gentamicin. We identified gene profiles that predicted each outcome through a classification analysis utilizing Random Forest machine learning techniques. Findings Our machine learning models predicted the outcomes accurately utilizing 67 enterotoxin and superantigen genes. Strong correlates predicting the genotypic expression of MRSA were enterotoxins A, D, J and R and superantigen-like proteins 1, 3, 7 and 10. Among these virulence factors, enterotoxin D and superantigen-like proteins 1, 5 and 10 were also significantly informative for predicting both MDR and MRSA in terms of phenotypic expression. Strong interactions were identified including enterotoxins A (entA) interacting with superantigen-like protein 1 (set6-var1_11), and enterotoxin D (entD) interacting with superantigen-like protein 5 (ssl05/set3_probe 1): MRSA and MDR S. aureus are associated with the presence of both entA and set6-var1_11, or both entD and ssl05/set3_probe 1, while the absence of these genes in pairs indicates non-multidrug-resistant and methicillin-susceptible S. aureus. Conclusions MRSA and MDR S. aureus show a different spectrum of ocular pathology than their non-resistant counterparts. When assessing the role of enterotoxins in predicting antibiotics resistance, it is critical to consider both main effects and interactions.

Staphylococcus aureus Efflux Pumps and Tolerance to Ciprofloxacin and Chlorhexidine following Induction by Mupirocin

2021 ◽  
Author(s):  
Q.C. Truong-Bolduc ◽  
Y. Wang ◽  
J. L. Reedy ◽  
J.M. Vyas ◽  
D.C. Hooper
Keyword(s):  
Staphylococcus Aureus ◽  
Efflux Pumps ◽  
Induced Expression ◽  
Expression Of Genes ◽  
Genes Encoding

Mupirocin induced expression of genes encoding efflux pumps NorA and MepA as well as a YFP fluorescence reporter of NorA. Mupirocin exposure also produced reduced susceptibility to pump substrates ciprofloxacin and chlorhexidine, a change that was dependent on intact norA and mepA , respectively.

scholarly journals sarZ, a sarA Family Gene, Is Transcriptionally Activated by MgrA and Is Involved in the Regulation of Genes Encoding Exoproteins in Staphylococcus aureus

2008 ◽  
Vol 191 (5) ◽  
pp. 1656-1665 ◽  
Author(s):  
Anand Ballal ◽  
Binata Ray ◽  
Adhar C. Manna
Keyword(s):  
Staphylococcus Aureus ◽  
Target Genes ◽  
Virulence Gene ◽  
Promoter Regions ◽  
Regulatory Relationship ◽  
Virulence Gene Expression ◽  
Regulatory Systems ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Gel Shift

ABSTRACT The expression of genes involved in the pathogenesis of Staphylococcus aureus is controlled by global regulatory loci, including two-component regulatory systems and transcriptional regulators (e.g., sar family genes). Most members of the SarA family have been partially characterized and shown to regulate a large numbers of target genes. Here, we describe the characterization of sarZ, a sarA paralog from S. aureus, and its regulatory relationship with other members of its family. Expression of sarZ was growth phase dependent with maximal expression in the early exponential phase of growth. Transcription of sarZ was reduced in an mgrA mutant and returned to a normal level in a complemented mgrA mutant strain, which suggests that mgrA acts as an activator of sarZ transcription. Purified MgrA protein bound to the sarZ promoter region, as determined by gel shift assays. Among the sarA family of genes analyzed, inactivation of sarZ increased sarS transcription, while it decreased agr transcription. The expression of potential target genes involved in virulence was evaluated in single and double mutants of sarZ with mgrA, sarX, and agr. Northern and zymogram analyses indicated that the sarZ gene product played a role in regulating several virulence genes, particularly those encoding exoproteins. Gel shift assays demonstrated nonspecific binding of purified SarZ protein to the promoter regions of the sarZ-regulated target genes. These results demonstrate the important role played by SarZ in controlling regulatory and virulence gene expression in S. aureus.

scholarly journals Influence of Tigecycline on Expression of Virulence Factors in Biofilm-Associated Cells of Methicillin-Resistant Staphylococcus aureus

2009 ◽  
Vol 54 (1) ◽  
pp. 380-387 ◽  
Author(s):  
Karen Smith ◽  
Katherine A. Gould ◽  
Gordon Ramage ◽  
Curtis G. Gemmell ◽  
Jason Hinds ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Phenotypic Diversity ◽  
Toxin Production ◽  
Sublethal Concentration ◽  
Methicillin Resistant ◽  
Reverse Transcription Pcr ◽  
Genes Encoding ◽  
Human Proteins ◽  
Biofilm Development

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) infections are complicated by the ability of the organism to grow in surface-adhered biofilms on a multitude of abiotic and biological surfaces. These multicellular communities are notoriously difficult to eradicate with antimicrobial therapy. Cells within the biofilm may be exposed to a sublethal concentration of the antimicrobial due to the metabolic and phenotypic diversity of the biofilm-associated cells or the protection offered by the biofilm structure. In the present study, the influence of a sublethal concentration of tigecycline on biofilms formed by an epidemic MRSA-16 isolate was investigated by transcriptome analysis. In the presence of the drug, 309 genes were upregulated and 213 genes were downregulated by more than twofold in comparison to the levels of gene regulation detected for the controls not grown in the presence of the drug. Microarray data were validated by real-time reverse transcription-PCR and phenotypic assays. Tigecycline altered the expression of a number of genes encoding proteins considered to be crucial for the virulence ofS. aureus. These included the reduced expression oficaC, which is involved in polysaccharide intercellular adhesin production and biofilm development; the upregulation offnbA,clfB, andcna, which encode adhesins which attach to human proteins; and the downregulation of thecapgenes, which mediate the synthesis of the capsule polysaccharide. The expression oftst, which encodes toxic shock syndrome toxin 1 (TSST-1), was also significantly reduced; and an assay performed to quantify TSST-1 showed that the level of toxin production by cells treated with tigecycline decreased by 10-fold (P< 0.001) compared to the level of production by untreated control cells. This study suggests that tigecycline may reduce the expression of important virulence factors inS. aureusand supports further investigation to determine whether it could be a useful adjunct to therapy for the treatment of biofilm-mediated infections.

scholarly journals Regulation of Exoprotein Gene Expression by the Staphylococcus aureus cvfB Gene

2007 ◽  
Vol 75 (4) ◽  
pp. 1964-1972 ◽  
Author(s):  
Yasuhiko Matsumoto ◽  
Chikara Kaito ◽  
Daisuke Morishita ◽  
Kenji Kurokawa ◽  
Kazuhisa Sekimizu
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Genetic Background ◽  
Promoter Activity ◽  
Double Mutant ◽  
Gene Deletion ◽  
Protein A ◽  
Protease Production ◽  
Gene Deletion Mutant

ABSTRACT We previously reported that the cvfB gene (SA1223) of Staphylococcus aureus is responsible for the virulence of this pathogenic bacterium. We show here that the cvfB gene regulates exoprotein gene expression. In a cvfB gene deletion mutant, hemolysin, DNase, and protease production were decreased, whereas protein A expression was increased. The amount of RNAIII, the transcript from the P3 promoter in the agr locus that regulates the expression of various virulence factors, was also reduced in the cvfB mutant. In addition, P2 and P3 promoter activity in the agr locus was decreased in the mutant. Under the genetic background of the agr-null mutation, cvfB gene disruption decreased the production levels of DNase and protease. Moreover, the cvfB and agr double mutant was less virulent than the agr mutant in silkworms. These results suggest that the cvfB gene product contributes to the expression of virulence factors and to pathogenicity via both agr-dependent and agr-independent pathways.

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