Phosphorylated CpxR restricts production of the rova global regulator in Yersinia pseudotuberculosis

Abstract

Background: RovA is a global transcriptional regulator of gene expression in pathogenic Yersinia. RovA levels are kept in check by a sophisticated layering of distinct transcriptional and post-transcriptional regulatory mechanisms. In the enteropathogen Y. pseudotuberculosis, we have previously reported that the extracytoplasmic stress sensing CpxA-CpxR two-component regulatory system modulates rovA expression. Methodology/Principal Findings: In this study, we characterized CpxR phosphorylation (CpxR~P) in vitro, and determined that phosphorylation was necessary for CpxR to efficiently bind to the PCR-amplified upstream regulatory region of rovA. The precise CpxR~P binding site was mapped by a nuclease protection assay and directed mutagenesis confirmed that in vivo binding to the rovA promoter inhibits transcription. Reduced RovA production was most pronounced following CpxR~P accumulation in the Yersinia cytoplasm during chronic Cpx pathway activation and by the indiscriminate phosphodonor action of acetyl phosphate. Conclusions/Significance: Cpx pathway activation restricts levels of the RovA global regulator. The regulatory influence of CpxR~P must therefore extend well beyond periplasmic quality control in the Yersinia envelope, to include genes involved in environmental survival and pathogenicity. © 2011 Liu et al.