A biochemical characterization of the DNA binding activity of the response regulator VicR from Streptococcus mutans.

Eduardo Ayala,Jennifer S Downey,Dilani B Senadheera,Dennis G Cvitkovitch,Steven D Goodman,Lauren Mashburn-Warren,Zezhang Wen

doi:10.1371/journal.pone.0108027

Eduardo Ayala, Jennifer S Downey + Show 5 more

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https://doi.org/10.1371/journal.pone.0108027

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Abstract

Two-component systems (TCSs) are ubiquitous among bacteria and are among the most elegant and effective sensing systems in nature. They allow for efficient adaptive responses to rapidly changing environmental conditions. In this study, we investigated the biochemical characteristics of the Streptococcus mutans protein VicR, an essential response regulator that is part of the VicRK TCS. We dissected the DNA binding requirements of the recognition sequences for VicR in its phosphorylated and unphosphorylated forms. In doing so, we were able to make predictions for the expansion of the VicR regulon within S. mutans. With the ever increasing number of bacteria that are rapidly becoming resistant to even the antibiotics of last resort, TCSs such as the VicRK provide promising targets for a new class of antimicrobials.

Highlights

Two-component signal transduction systems (TCSs) are used by bacteria to sense environmental cues and regulate gene expression in response to them [1]
Regulatory Sequence Analysis Tools (RSAT) analysis did not yield matches to the consensus in relP, glnQ or copY, whose virulence traits have been demonstrated to be regulated by vicRK [9,11,28]
The upstream regions of these latter three genes were analyzed manually for potential matches to the WalR consensus because these genes were identified in a VicK mutant microarray, linked to competence or acid tolerance [9,11,29]

Summary

Introduction

Two-component signal transduction systems (TCSs) are used by bacteria to sense environmental cues and regulate gene expression in response to them [1]. TCSs are typically composed of a membrane-bound sensor histidine kinase (HK) [2] that perceives a signal and transmits it through phosphoryl transfer to a cognate cytoplasmic response regulator (RR) [3]. In Streptococcus mutans the VicRK TCS is essential and regulates key virulence attributes [6]. Biofilm formation, sucrose mediated adhesion, oxidative stress tolerance, acid production, acid tolerance, bacteriocin production and cell wall metabolism are all under the control of the VicRK TCS [6,7,8,9,10,11]. The conservation and essentiality across low G+C Grampositive bacteria have made this TCS an attractive target for the development of new antimicrobials [12]. Various inhibitors of VicK and VicR homologues in B. subtilis, Staphylococcus aureus, and Staphylococcus epidermidis have been identified and were shown to exhibit bactericidal effects on these organisms [13,14,15]

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