Dataset Information

DksA-DnaJ redox interactions provide a signal for the activation of bacterial RNA polymerase.

ABSTRACT: RNA polymerase is the only known protein partner of the transcriptional regulator DksA. Herein, we demonstrate that the chaperone DnaJ establishes direct, redox-based interactions with oxidized DksA. Cysteine residues in the zinc finger of DksA become oxidized in Salmonella exposed to low concentrations of hydrogen peroxide (H2O2). The resulting disulfide bonds unfold the globular domain of DksA, signaling high-affinity interaction of the C-terminal ?-helix to DnaJ. Oxidoreductase and chaperone activities of DnaJ reduce the disulfide bonds of its client and promote productive interactions between DksA and RNA polymerase. Simultaneously, guanosine tetraphosphate (ppGpp), which is synthesized by RelA in response to low concentrations of H2O2, binds at site 2 formed at the interface of DksA and RNA polymerase and synergizes with the DksA/DnaJ redox couple, thus activating the transcription of genes involved in amino acid biosynthesis and transport. However, the high concentrations of ppGpp produced by Salmonella experiencing oxidative stress oppose DksA/DnaJ-dependent transcription. Cumulatively, the interplay of DksA, DnaJ, and ppGpp on RNA polymerase protects Salmonella from the antimicrobial activity of the NADPH phagocyte oxidase. Our research has identified redox-based signaling that activates the transcriptional activity of the RNA polymerase regulator DksA.

SUBMITTER: Kim JS

PROVIDER: S-EPMC6294903 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

DksA-DnaJ redox interactions provide a signal for the activation of bacterial RNA polymerase.

Kim Ju-Sim JS Liu Lin L Fitzsimmons Liam F LF Wang Yang Y Crawford Matthew A MA Mastrogiovanni Mauricio M Trujillo Madia M Till James Karl A JKA Radi Rafael R Dai Shaodong S Vázquez-Torres Andrés A

Proceedings of the National Academy of Sciences of the United States of America 20181114 50

RNA polymerase is the only known protein partner of the transcriptional regulator DksA. Herein, we demonstrate that the chaperone DnaJ establishes direct, redox-based interactions with oxidized DksA. Cysteine residues in the zinc finger of DksA become oxidized in Salmonella exposed to low concentrations of hydrogen peroxide (H2O2). The resulting disulfide bonds unfold the globular domain of DksA, signaling high-affinity interaction of the C-terminal α-helix to DnaJ. ...[more]

PMID: 30429329

Similar Datasets

Project description:UNLABELLED:The four-cysteine zinc finger motif of the bacterial RNA polymerase regulator DksA is essential for protein structure, canonical control of the stringent response to nutritional limitation, and thiol-based sensing of oxidative and nitrosative stress. This interdependent relationship has limited our understanding of DksA-mediated functions in bacterial pathogenesis. Here, we have addressed this challenge by complementing ?dksA Salmonella with Pseudomonas aeruginosa dksA paralogues that encode proteins differing in cysteine and zinc content. We find that four-cysteine, zinc-bound (C4) and two-cysteine, zinc-free (C2) DksA proteins are able to mediate appropriate stringent control in Salmonella and that thiol-based sensing of reactive species is conserved among C2 and C4 orthologues. However, variations in cysteine and zinc content determine the threshold at which individual DksA proteins sense and respond to reactive species. In particular, zinc acts as an antioxidant, dampening cysteine reactivity and raising the threshold of posttranslational thiol modification with reactive species. Consequently, C2 DksA triggers transcriptional responses in Salmonella at levels of oxidative or nitrosative stress normally tolerated by Salmonella expressing C4 orthologues. Inappropriate transcriptional regulation by C2 DksA increases the susceptibility of Salmonella to the antimicrobial effects of hydrogen peroxide and nitric oxide, and attenuates virulence in macrophages and mice. Our findings suggest that the redox-active sensory function of DksA proteins is finely tuned to optimize bacterial fitness according to the levels of oxidative and nitrosative stress encountered by bacterial species in their natural and host environments. IMPORTANCE:In order to cause disease, pathogenic bacteria must rapidly sense and respond to antimicrobial pressures encountered within the host. Prominent among these stresses, and of particular relevance to intracellular pathogens such as Salmonella, are nutritional restriction and the enzymatic generation of reactive oxygen and nitrogen species. The conserved transcriptional regulator DksA controls adaptive responses to nutritional limitation, as well as to oxidative and nitrosative stress. Here, we demonstrate that each of these functions contributes to bacterial pathogenesis. Our observations highlight the importance of metabolic adaptation in bacterial pathogenesis and show the mechanism by which DksA orthologues are optimized to sense the levels of oxidative and nitrosative stress encountered in their natural habitats. An improved understanding of the conserved processes used by bacteria to sense, respond to, and limit host defense will inform the development of novel strategies to treat infections caused by pathogenic, potentially multidrug-resistant bacteria.

Dataset Information

DksA-DnaJ redox interactions provide a signal for the activation of bacterial RNA polymerase.

Publications

DksA-DnaJ redox interactions provide a signal for the activation of bacterial RNA polymerase.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets