The metabolic regulator CodY links Listeria monocytogenes metabolism to virulence by directly activating the virulence regulatory gene prfA

Mol Microbiol. 2015 Feb;95(4):624-44. doi: 10.1111/mmi.12890. Epub 2014 Dec 30.

Abstract

Metabolic adaptations are critical to the ability of bacterial pathogens to grow within host cells and are normally preceded by sensing of host-specific metabolic signals, which in turn can influence the pathogen's virulence state. Previously, we reported that the intracellular bacterial pathogen Listeria monocytogenes responds to low availability of branched-chain amino acids (BCAAs) within mammalian cells by up-regulating both BCAA biosynthesis and virulence genes. The induction of virulence genes required the BCAA-responsive transcription regulator, CodY, but the molecular mechanism governing this mode of regulation was unclear. In this report, we demonstrate that CodY directly binds the coding sequence of the L. monocytogenes master virulence activator gene, prfA, 15 nt downstream of its start codon, and that this binding results in up-regulation of prfA transcription specifically under low concentrations of BCAA. Mutating this site abolished CodY binding and reduced prfA transcription in macrophages, and attenuated bacterial virulence in mice. Notably, the mutated binding site did not alter prfA transcription or PrfA activity under other conditions that are known to activate PrfA, such as during growth in the presence of glucose-1-phosphate. This study highlights the tight crosstalk between L. monocytogenes metabolism and virulence, while revealing novel features of CodY-mediated regulation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids, Branched-Chain / metabolism*
  • Animals
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Chromatin Immunoprecipitation
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Regulation, Bacterial*
  • Genes, Regulator
  • Glucosephosphates / metabolism
  • Listeria monocytogenes / genetics*
  • Listeria monocytogenes / growth & development
  • Listeria monocytogenes / metabolism*
  • Listeria monocytogenes / pathogenicity
  • Macrophages / microbiology
  • Mice
  • Mice, Inbred C57BL
  • Mutation
  • Operon
  • Peptide Termination Factors / genetics*
  • Peptide Termination Factors / metabolism
  • Promoter Regions, Genetic
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism*
  • Transcriptional Activation
  • Up-Regulation
  • Virulence / genetics

Substances

  • Amino Acids, Branched-Chain
  • Bacterial Proteins
  • Glucosephosphates
  • Peptide Termination Factors
  • PrfA protein, Listeria monocytogenes
  • Transcription Factors
  • glucose-1-phosphate