Protein cysteine phosphorylation of SarA/MgrA family transcriptional regulators mediates bacterial virulence and antibiotic resistance

Abstract

Protein posttranslational modifications (PTMs), particularly phosphorylation, dramatically expand the complexity of cellular regulatory networks. Although cysteine (Cys) in various proteins can be subject to multiple PTMs, its phosphorylation was previously considered a rare PTM with almost no regulatory role assigned. We report here that phosphorylation occurs to a reactive cysteine residue conserved in the staphylococcal accessary regulator A (SarA)/MarR family global transcriptional regulator A (MgrA) family of proteins, and is mediated by the eukaryotic-like kinase-phosphatase pair Stk1-Stp1 in Staphylococcus aureus. Cys-phosphorylation is crucial in regulating virulence determinant production and bacterial resistance to vancomycin. Cell wall-targeting antibiotics, such as vancomycin and ceftriaxone, inhibit the kinase activity of Stk1 and lead to decreased Cys-phosphorylation of SarA and MgrA. An in vivo mouse model of infection established that the absence of stp1, which results in elevated protein Cys-phosphorylation, significantly reduces staphylococcal virulence. Our data indicate that Cys-phosphorylation is a unique PTM that can play crucial roles in bacterial signaling and regulation.

RNAIII of the Staphylococcus aureus agr system activates global regulator MgrA by stabilizing mRNA

“…Thus, taken together, we envision that MgrA production could be influenced by multiple signals in which transcripts initiated from the P2 promoter could be controlled by quorum sensing through RNAIII, whereas transcripts from both promoters could be controlled by different stimuli by interacting with RsaA through SigB, as well as an unknown regulatory element. The various modes of regulation at the mRNA level and the fact that the regulatory function of MgrA can be modulated by oxidation or phosphorylation at a conserved cysteine residue (37)(38)(39) indicate that MgrA regulatory function is likely modulated by multiple signals. Because MgrA has been shown to affect more than 350 genes and plays an important role in virulence regulation (25,37,40,41), it is not surprising that the activity of MgrA is affected by multiple elements.…”

Metabolic sensor governing bacterial virulence in Staphylococcus aureus

“…To test further the role of ccpE in invasive staphylococcal disease, we subjected the test strains-wild type, ΔccpE, and ΔccpE-C-to a murine model of abscess formation (24,39) and measured the bacterial survival in host organs. As shown in Fig.…”

A Novel Mode of Regulation of the Staphylococcus aureus Catabolite Control Protein A (CcpA) Mediated by Stk1 Protein Phosphorylation

“…Recent studies provided the first insights into the regulatory function of Stk1 and the molecular mechanisms of the Ser/Thr phosphorylation system in S. aureus (17). Interestingly, the Ser/Thr kinase Stk1 was identified to influence central metabolic processes in S. aureus (18) and the activity of important regulatory factors such as SarA (19), MgrA (20), and LuxS (21). Therefore, we investigated the possible regulation of CcpA by Stk1.…”