Organizational Requirements of the SaeR Binding Sites for a Functional P1 Promoter of the
            <i>sae</i>
            Operon in Staphylococcus aureus

Cho, Hoonsik; Jeong, Do‐Won; Li, Chunling; Bae, Taeok

doi:10.1128/jb.06771-11

Cited by 19 publications

(19 citation statements)

References 55 publications

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“…5). As expected based on previous studies (12,(15)(16)(17)25), we observed a dose-dependent transcriptional response in the wild-type strain in the presence of 0, 0.5, 2.5, or 5.0 g ml Ϫ1 HNP-1. The coa promoter activity in the vfrB mutant in the presence of low HNP-1 concentrations (0.5 g ml Ϫ1 ) had a similar reduction (4.7-fold) as when no HNP-1 was added.…”

Section: Resultssupporting

confidence: 74%

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

2017

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In previous studies, we identified the fatty acid kinase virulence factor regulator B (VfrB) as a potent regulator of ␣-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 ␣-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 twocomponent 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.

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Section: Resultssupporting

confidence: 74%

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

2017

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“…S2). This observation is consistent with previous work showing sae regulates transcription of hla (11,25). Both WT LAC and ΔsaeS containing the hla reporter were transformed with the empty complementation vector pEPSA5 (WT v and ΔsaeS v, respectively), and complementation of the ΔsaeS mutant with WT SaeS restored both P hla fluorescence and RBC lysis ( Fig.…”

Section: Mutagenesis Of the Predicted Extracellular Loop Of Saes Idensupporting

confidence: 78%

Differential regulation of staphylococcal virulence by the sensor kinase SaeS in response to neutrophil-derived stimuli

Flack

Zurek

Meishery

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Two-component systems (TCSs) are highly conserved across bacteria and are used to rapidly sense and respond to changing environmental conditions. The human pathogen Staphylococcus aureus uses the S. aureus exoprotein expression (sae) TCS to sense host signals and activate transcription of virulence factors essential to pathogenesis. Despite its importance, the mechanism by which the histidine kinase SaeS recognizes specific host stimuli is unknown. After mutagenizing the predicted extracellular loop of SaeS, we discovered one methionine residue (M31) was essential for the ability of S. aureus to transcribe sae target genes, including hla, lukAB/lukGH, and hlgA. This single M31A mutation also significantly reduced cytotoxicity in human neutrophils to levels observed in cells following interaction with ΔsaeS. Another important discovery was that mutation of two aromatic anchor residues (W32A and F33A) disrupted the normal basal signaling of SaeS in the absence of inducing signals, yet both mutant kinases had appropriate activation of effector genes following exposure to neutrophils. Although the transcriptional profile of aromatic mutation W32A was consistent with that of WT in response to human α-defensin 1, mutant kinase F33A did not properly transcribe the γ-toxin genes in response to this stimulus. Taken together, our results provide molecular evidence for how SaeS recognizes host signals and triggers activation of select virulence factors to facilitate evasion of innate immunity. These findings have important implications for signal transduction in prokaryotes and eukaryotes due to conservation of aromatic anchor residues across both of these domains and the important role they play in sensor protein structure and function.host-pathogen interactions | membrane proteins

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“…We speculate that Rot may recruit SaeR to the ssl promoters, which in turn will recruit the RNA polymerase and activate gene expression (12). The notion that Rot facilitates the recruitment of SaeR to the ssl promoters is supported by the fact that less SaeR is required to create a supershift of the ssl7, ssl9, and ssl11 promoter DNAs in the presence of Rot than when Rot is absent (Fig.…”

Section: Figmentioning

confidence: 58%

Rot and SaeRS Cooperate To Activate Expression of the Staphylococcal Superantigen-Like Exoproteins

et al. 2012

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Staphylococcus aureus is a significant human pathogen that is capable of infecting a wide range of host tissues. This bacterium is able to evade the host immune response by utilizing a repertoire of virulence factors. These factors are tightly regulated by various two-component systems (TCS) and transcription factors. Previous studies have suggested that transcriptional regulation of a subset of immunomodulators, known as the staphylococcal superantigen-like proteins (Ssls), is mediated by the master regulators accessory gene regulator (Agr) TCS, S. aureus exoprotein expression (Sae) TCS, and Rot. Here we demonstrate that Rot and SaeR, the response regulator of the Sae TCS, synergize to coordinate the activation of the ssl promoters. We have determined that both transcription factors are required, but that neither is sufficient, for promoter activation. This regulatory scheme is mediated by direct binding of both transcription factors to the ssl promoters. We also demonstrate that clinically relevant methicillinresistant S. aureus (MRSA) strains respond to neutrophils via the Sae TCS to upregulate the expression of ssls. Until now, Rot and the Sae TCS have been proposed to work in opposition of one another on their target genes. This is the first example of these two regulators working in concert to activate promoters.

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Organizational Requirements of the SaeR Binding Sites for a Functional P1 Promoter of the sae Operon in Staphylococcus aureus

Cited by 19 publications

References 55 publications

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

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

Differential regulation of staphylococcal virulence by the sensor kinase SaeS in response to neutrophil-derived stimuli

Rot and SaeRS Cooperate To Activate Expression of the Staphylococcal Superantigen-Like Exoproteins

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