The auxiliary protein complex <scp>SaePQ</scp> activates the phosphatase activity of sensor kinase <scp>SaeS</scp> in the <scp>SaeRS</scp> two‐component system of <i><scp>S</scp>taphylococcus aureus</i>

Jeong, Do‐Won; Cho, Hoonsik; Jones, Marcus B.; Shatzkes, Kenneth; Sun, Fei; Ji, Quanjiang; Liu, Qian; Peterson, Scott N.; He, Chuan; Bae, Taeok

doi:10.1111/j.1365-2958.2012.08198.x

Cited by 75 publications

(99 citation statements)

References 82 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%

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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%

“…SaeRS has been shown to be activated by several antibiotics and ␣-defensins (17,21), including human neutrophil peptide 1 (HNP-1), resulting in increased transcription of class I target genes such as coa (15)(16)(17). This occurs when extracellular HNP-1 interacts with an extracellular loop of SaeS (13).…”

Section: Resultsmentioning

confidence: 99%

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

2017

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“…Another possibility is that mutation of W32 or F33 may alter protein-protein interactions within the SaeS homodimer or the SaePQS complex, resulting in the altered gene expression we observed. The recent finding that auxiliary proteins SaeP and SaeQ stimulate the phosphatase activity of the bifunctional kinase to modulate expression of the sae regulon supports this hypothesis (18). More studies are needed to investigate these possibilities and to examine the effect of other point mutations on the refinement of the pathogen response to stimuli.…”

Section: Discussionmentioning

confidence: 79%

“…nals (18). However, formation of the protein complex results in repression of the sae system and not activation.…”

Section: Significancementioning

confidence: 99%

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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“…These auxiliary proteins have been identified in all cellular compartments, and their mechanisms of action vary from one system to another (Buelow & Raivio, 2010). Auxiliary proteins have been shown to link multiple TCSs to one another, to interrupt stimulus detection by the SK, or to modulate SK autophosphorylation, phosphotransfer or phosphatase activities (Chen et al, 2008;Garnerone et al, 1999;Gerken et al, 2009;Jeong et al, 2012;Mitrophanov & Groisman, 2008;Neiditch et al, 2006;Pioszak & Ninfa, 2003a;Szurmant et al, 2008).…”

Section: Introductionmentioning

confidence: 99%