scholarly journals Characterization of Virulence Factor Regulation by SrrAB, a Two-Component System in Staphylococcus aureus

2004 ◽  
Vol 186 (8) ◽  
pp. 2430-2438 ◽  
Author(s):  
Alexa A. Pragman ◽  
Jeremy M. Yarwood ◽  
Timothy J. Tripp ◽  
Patrick M. Schlievert
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Transcriptional Start Site ◽  
Protein A ◽  
Rabbit Model ◽  
Low Oxygen ◽  
Two Component System ◽  
Component System ◽  
Two Component

ABSTRACT Workers in our laboratory have previously identified the staphylococcal respiratory response AB (SrrAB), a Staphylococcus aureus two-component system that acts in the global regulation of virulence factors. This system down-regulates production of agr RNAIII, protein A, and toxic shock syndrome toxin 1 (TSST-1), particularly under low-oxygen conditions. In this study we investigated the localization and membrane orientation of SrrA and SrrB, transcription of the srrAB operon, the DNA-binding properties of SrrA, and the effect of SrrAB expression on S. aureus virulence. We found that SrrA is localized to the S. aureus cytoplasm, while SrrB is localized to the membrane and is properly oriented to function as a histidine kinase. srrAB has one transcriptional start site which results in either an srrA transcript or a full-length srrAB transcript; srrB must be cotranscribed with srrA. Gel shift assays of the agr P2, agr P3, protein A (spa), TSST-1 (tst), and srr promoters revealed SrrA binding at each of these promoters. Analysis of SrrAB-overexpressing strains by using the rabbit model of bacterial endocarditis demonstrated that overexpression of SrrAB decreased the virulence of the organisms compared to the virulence of isogenic strains that do not overexpress SrrAB. We concluded that SrrAB is properly localized and oriented to function as a two-component system. Overexpression of SrrAB, which represses agr RNAIII, TSST-1, and protein A in vitro, decreases virulence in the rabbit endocarditis model. Repression of these virulence factors is likely due to a direct interaction between SrrA and the agr, tst, and spa promoters.

scholarly journals VfrB Is a Key Activator of the Staphylococcus aureus SaeRS Two-Component System

2016 ◽  
Vol 199 (5) ◽  
Author(s):  
Christina N. Krute ◽  
Kelly C. Rice ◽  
Jeffrey L. Bose
Keyword(s):  
Staphylococcus Aureus ◽  
Fatty Acid ◽  
Virulence Factors ◽  
Virulence Factor ◽  
Class I ◽  
Exponential Growth Phase ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Two Component

ABSTRACT In previous studies, we identified the fatty acid kinase virulence factor regulator B (VfrB) as a potent regulator of α-hemolysin and other virulence factors in Staphylococcus aureus. In this study, we demonstrated that VfrB is a positive activator of the SaeRS two-component regulatory system. Analysis of vfrB, saeR, and saeS mutant strains revealed that VfrB functions in the same pathway as SaeRS. At the transcriptional level, the promoter activities of SaeRS class I (coa) and class II (hla) target genes were downregulated during the exponential growth phase in the vfrB mutant, compared to the wild-type strain. In addition, saePQRS expression was decreased in the vfrB mutant strain, demonstrating a need for this protein in the autoregulation of SaeRS. The requirement for VfrB-mediated activation was circumvented when SaeS was constitutively active due to an SaeS (L18P) substitution. Furthermore, activation of SaeS via human neutrophil peptide 1 (HNP-1) overcame the dependence on VfrB for transcription from class I Sae promoters. Consistent with the role of VfrB in fatty acid metabolism, hla expression was decreased in the vfrB mutant with the addition of exogenous myristic acid. Lastly, we determined that aspartic acid residues D38 and D40, which are predicted to be key to VfrB enzymatic activity, were required for VfrB-mediated α-hemolysin production. Collectively, this study implicates VfrB as a novel accessory protein needed for the activation of SaeRS in S. aureus. IMPORTANCE The SaeRS two-component system is a key regulator of virulence determinant production in Staphylococcus aureus. Although the regulon of this two-component system is well characterized, the activation mechanisms, including the specific signaling molecules, remain elusive. Elucidating the complex regulatory circuit of SaeRS regulation is important for understanding how the system contributes to disease causation by this pathogen. To this end, we have identified the fatty acid kinase VfrB as a positive regulatory modulator of SaeRS-mediated transcription of virulence factors in S. aureus. In addition to describing a new regulatory aspect of SaeRS, this study establishes a link between fatty acid kinase activity and virulence factor regulation.

Protein A gene expression is regulated by DNA supercoiling which is modified by the ArlS–ArlR two-component system of Staphylococcus aureus

Microbiology ◽  
2004 ◽  
Vol 150 (11) ◽  
pp. 3807-3819 ◽  
Author(s):  
Bénédicte Fournier ◽  
André Klier
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Virulence Genes ◽  
Protein A ◽  
Dna Gyrase ◽  
Dna Supercoiling ◽  
Two Component System ◽  
Component System ◽  
High Osmolarity ◽  
Two Component

Bacterial pathogens such as Staphylococcus aureus undergo major physiological changes when they infect their hosts, requiring the coordinated regulation of gene expression in response to the stresses encountered. Several environmental factors modify the expression of S. aureus virulence genes. This report shows that the expression of spa (virulence gene encoding the cell-wall-associated protein A) is down-regulated by high osmolarity (1 M NaCl, 1 M KCl or 1 M sucrose) in the wild-type strain and upregulated by novobiocin (a DNA gyrase inhibitor that relaxes DNA). A gyrB142 allele corresponding to a double mutation in the B subunit of DNA gyrase relaxed DNA and consequently induced spa expression, confirming that spa expression is regulated by DNA topology. Furthermore, in the presence of novobiocin plus 1 M NaCl, a good correlation was observed between DNA supercoiling and spa expression. The ArlS–ArlR two-component system is involved in the expression of virulence genes such as spa. Presence of an arlRS deletion decreased the effect of DNA supercoiling modulators on spa expression, suggesting that active Arl proteins are necessary for the full effect of DNA gyrase inhibitors and high osmolarity on spa expression. Indeed, evidence is provided for a relationship between the arlRS deletion and topological changes in plasmid DNA.

scholarly journals Influence of the Two-Component System SaeRS on Global Gene Expression in Two Different Staphylococcus aureus Strains

2006 ◽  
Vol 188 (22) ◽  
pp. 7742-7758 ◽  
Author(s):  
Kathrin Rogasch ◽  
Vanessa Rühmling ◽  
Jan Pané-Farré ◽  
Dirk Höper ◽  
Christin Weinberg ◽  
...  
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Global Gene Expression ◽  
Extracellular Proteins ◽  
Transcriptional Level ◽  
Two Component System ◽  
Component System ◽  
Virulence Gene Expression ◽  
Two Component

ABSTRACT The two-component system SaeRS consisting of the histidin kinase SaeS and the response regulator SaeR is known to act on virulence gene expression in Staphylococcus aureus. In order to get a more comprehensive picture on SaeR-regulated genes, we studied the contribution of the two-component system on global gene expression by using both the proteomic and transcriptomic approach. Altogether, a loss of SaeRS resulted in a decreased amount of at least 17 extracellular proteins and two cell surface-associated proteins, among them several important virulence factors such as HlgA, HlgB, HlgC, LukF, and LukM. SaeRS activates the expression of these genes at the transcriptional level. The amount of the five proteins Aur, SspA, SsaA, Plc, and GlpQ was negatively influenced by SaeRS. However, the transcription of the corresponding genes was not affected by the two-component system. SaeRS had also no measurable influence on the transcription of the regulatory genes agr, sarA, arlRS, and sigB that contribute to the regulation of SaeRS-dependent virulence factors identified in this investigation. Our results clearly show that SaeRS is strongly involved in the tight temporal control of virulence factor expression in S. aureus. Its precise role within the regulatory network remains to be determined.

scholarly journals Identification of Genes Controlled by the Essential YycG/YycF Two-Component System of Staphylococcus aureus

2004 ◽  
Vol 186 (4) ◽  
pp. 1175-1181 ◽  
Author(s):  
Sarah Dubrac ◽  
Tarek Msadek
Keyword(s):  
Staphylococcus Aureus ◽  
Regulatory System ◽  
Inducible Promoter ◽  
Motif Analysis ◽  
Two Component System ◽  
Recognition Sequence ◽  
Mobility Shift ◽  
Component System ◽  
Two Component

ABSTRACT The YycG/YycF essential two-component system (TCS), originally identified in Bacillus subtilis, is very highly conserved and appears to be specific to low-G+C gram-positive bacteria, including several pathogens such as Staphylococcus aureus. By studying growth of S. aureus cells where the yyc operon is controlled by an isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible promoter, we have shown that this system is essential in S. aureus during growth at 37°C and that starvation for the YycG/YycF regulatory system leads to cell death. During a previous study of the YycG/YycF TCS of B. subtilis, we defined a potential YycF consensus recognition sequence, consisting of two hexanucleotide direct repeats, separated by five nucleotides [5′-TGT(A/T)A(A/T/C)-N5-TGT(A/T)A(A/T/C)-3′]. A detailed DNA motif analysis of the S. aureus genome indicates that there are potentially 12 genes preceded by this sequence, 5 of which are involved in virulence. An in vitro approach was undertaken to determine which of these genes are controlled by YycF. The YycG and YycF proteins of S. aureus were overproduced in Escherichia coli and purified. Autophosphorylation of the YycG kinase and phosphotransfer to YycF were shown in vitro. Gel mobility shift and DNase I footprinting assays were used to show direct binding in vitro of purified YycF to the promoter region of the ssaA gene, encoding a major antigen and previously suggested to be controlled by YycF. YycF was also shown to bind specifically to the promoter regions of two genes, encoding the IsaA antigen and the LytM peptidoglycan hydrolase, in agreement with the proposed role of this system in controlling virulence and cell wall metabolism.

scholarly journals Nutritional Regulation of the Sae Two-Component System by CodY inStaphylococcus aureus

2018 ◽  
Vol 200 (8) ◽  
Author(s):  
Kevin D. Mlynek ◽  
William E. Sause ◽  
Derek E. Moormeier ◽  
Marat R. Sadykov ◽  
Kurt R. Hill ◽  
...  
Keyword(s):  
Gene Expression ◽  
Virulence Factors ◽  
Virulence Gene ◽  
Nutrient Depletion ◽  
Global Regulator ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Two Component

ABSTRACTStaphylococcus aureussubverts innate defenses during infection in part by killing host immune cells to exacerbate disease. This human pathogen intercepts host cues and activates a transcriptional response via theS. aureusexoprotein expression (SaeR/SaeS [SaeR/S]) two-component system to secrete virulence factors critical for pathogenesis. We recently showed that the transcriptional repressor CodY adjusts nuclease (nuc) gene expression via SaeR/S, but the mechanism remained unknown. Here, we identified two CodY binding motifs upstream of thesaeP1 promoter, which suggested direct regulation by this global regulator. We show that CodY shares a binding site with the positive activator SaeR and that alleviating direct CodY repression at this site is sufficient to abrogate stochastic expression, suggesting that CodY repressessaeexpression by blocking SaeR binding. Epistasis experiments support a model that CodY also controlssaeindirectly through Agr and Rot-mediated repression of thesaeP1 promoter. We also demonstrate that CodY repression ofsaerestrains production of secreted cytotoxins that kill human neutrophils. We conclude that CodY plays a previously unrecognized role in controlling virulence gene expression via SaeR/S and suggest a mechanism by which CodY acts as a master regulator of pathogenesis by tying nutrient availability to virulence gene expression.IMPORTANCEBacterial mechanisms that mediate the switch from a commensal to pathogenic lifestyle are among the biggest unanswered questions in infectious disease research. Since the expression of most virulence genes is often correlated with nutrient depletion, this implies that virulence is a response to the lack of nourishment in host tissues and that pathogens likeS. aureusproduce virulence factors in order to gain access to nutrients in the host. Here, we show that specific nutrient depletion signals appear to be funneled to the SaeR/S system through the global regulator CodY. Our findings reveal a strategy by whichS. aureusdelays the production of immune evasion and immune-cell-killing proteins until key nutrients are depleted.

The Bacillus subtilis ywkA gene encodes a malic enzyme and its transcription is activated by the YufL/YufM two-component system in response to malate

Microbiology ◽  
2003 ◽  
Vol 149 (9) ◽  
pp. 2331-2343 ◽  
Author(s):  
Thierry Doan ◽  
Pascale Servant ◽  
Shigeo Tojo ◽  
Hirotake Yamaguchi ◽  
Guillaume Lerondel ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Malic Enzyme ◽  
Northern Analysis ◽  
Two Component System ◽  
Extracellular Medium ◽  
Component System ◽  
Two Component ◽  
Transcriptome Comparison ◽  
Physiological Tests

A transcriptome comparison of a wild-type Bacillus subtilis strain growing under glycolytic or gluconeogenic conditions was performed. In particular, it revealed that the ywkA gene, one of the four paralogues putatively encoding a malic enzyme, was more transcribed during gluconeogenesis. Using a lacZ reporter fusion to the ywkA promoter, it was shown that ywkA was specifically induced by external malate and not subject to glucose catabolite repression. Northern analysis confirmed this expression pattern and demonstrated that ywkA is cotranscribed with the downstream ywkB gene. The ywkA gene product was purified and biochemical studies demonstrated its malic enzyme activity, which was 10-fold higher with NAD than with NADP (k cat/K m 102 and 10 s−1 mM−1, respectively). However, physiological tests with single and multiple mutant strains affected in ywkA and/or in ywkA paralogues showed that ywkA does not contribute to efficient utilization of malate for growth. Transposon mutagenesis allowed the identification of the uncharacterized YufL/YufM two-component system as being responsible for the control of ywkA expression. Genetic analysis and in vitro studies with purified YufM protein showed that YufM binds just upstream of ywkA promoter and activates ywkA transcription in response to the presence of malate in the extracellular medium, transmitted by YufL. ywkA and yufL/yufM could thus be renamed maeA for malic enzyme and malK/malR for malate kinase sensor/malate response regulator, respectively.

scholarly journals The Staphylococcus aureus KdpDE Two-Component System Couples Extracellular K+Sensing and Agr Signaling to Infection Programming

2011 ◽  
Vol 79 (6) ◽  
pp. 2154-2167 ◽  
Author(s):  
Ting Xue ◽  
Yibo You ◽  
De Hong ◽  
Haipeng Sun ◽  
Baolin Sun
Keyword(s):  
Staphylococcus Aureus ◽  
Uptake System ◽  
Main Function ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Virulence Regulator ◽  
External K

ABSTRACTThe Kdp system is widely distributed among bacteria. InEscherichia coli, the Kdp-ATPase is a high-affinity K+uptake system and its expression is activated by the KdpDE two-component system in response to K+limitation or salt stress. However, information about the role of this system in many bacteria still remains obscure. Here we demonstrate that KdpFABC inStaphylococcus aureusis not a major K+transporter and that the main function of KdpDE is not associated with K+transport but that instead it regulates transcription for a series of virulence factors through sensing external K+concentrations, indicating that this bacterium might modulate its infectious status through sensing specific external K+stimuli in different environments. Our results further reveal thatS. aureusKdpDE is upregulated by the Agr/RNAIII system, which suggests that KdpDE may be an important virulence regulator coordinating the external K+sensing and Agr signaling during pathogenesis in this bacterium.

scholarly journals Signaling mechanism by the Staphylococcus aureus two-component system LytSR: role of acetyl phosphate in bypassing the cell membrane electrical potential sensor LytS

F1000Research ◽  
2016 ◽  
Vol 4 ◽  
pp. 79 ◽  
Author(s):  
Kevin Patel ◽  
Dasantila Golemi-Kotra
Keyword(s):  
Staphylococcus Aureus ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Electrical Potential ◽  
Cell Membrane Potential ◽  
Acetyl Phosphate ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Membrane Electrical Potential

The two-component system LytSR has been linked to the signal transduction of cell membrane electrical potential perturbation and is involved in the adaptation of Staphylococcus aureus to cationic antimicrobial peptides. It consists of a membrane-bound histidine kinase, LytS, which belongs to the family of multiple transmembrane-spanning domains receptors, and a response regulator, LytR, which belongs to the novel family of non-helix-turn-helix DNA-binding domain proteins. LytR regulates the expression of cidABC and lrgAB operons, the gene products of which are involved in programmed cell death and lysis. In vivo studies have demonstrated involvement of two overlapping regulatory networks in regulating the lrgAB operon, both depending on LytR. One regulatory network responds to glucose metabolism and the other responds to changes in the cell membrane potential. Herein, we show that LytS has autokinase activity and can catalyze a fast phosphotransfer reaction, with 50% of its phosphoryl group lost within 1 minute of incubation with LytR. LytS has also phosphatase activity. Notably, LytR undergoes phosphorylation by acetyl phosphate at a rate that is 2-fold faster than the phosphorylation by LytS. This observation is significant in lieu of the in vivo observations that regulation of the lrgAB operon is LytR-dependent in the presence of excess glucose in the medium. The latter condition does not lead to perturbation of the cell membrane potential but rather to the accumulation of acetate in the cell. Our study provides insights into the molecular basis for regulation of lrgAB in a LytR-dependent manner under conditions that do not involve sensing by LytS.

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