NemR is a bleach-sensing transcription factor

J Biol Chem. 2013 May 10;288(19):13789-98. doi: 10.1074/jbc.M113.454421. Epub 2013 Mar 27.

Abstract

Background: Little is known about how bacteria sense or respond to reactive chlorine species, such as bleach.

Results: NemR is a redox-regulated transcription factor which senses bleach.

Conclusion: NemR controls expression of genes encoding electrophile detoxification enzymes, which increase bleach resistance.

Significance: We demonstrate a bleach-sensing bacterial response system and a new mechanism contributing to bacterial bleach survival. Hypochlorous acid (HOCl), the active component of household bleach, also functions as a powerful antimicrobial during the innate immune response. Despite its widespread use, surprisingly little is known about how cells sense or respond to HOCl. We now demonstrate that Escherichia coli NemR is a redox-regulated transcriptional repressor, which uses the oxidation status of HOCl-sensitive cysteine residues to respond to bleach and related reactive chlorine species. NemR controls bleach-mediated expression of two enzymes required for detoxification of reactive electrophiles: glyoxalase I and N-ethylmaleimide reductase. Both enzymes contribute to bacterial bleach survival. These results provide evidence that bleach resistance relies on the capacity of organisms to specifically sense reactive chlorine species and respond with the up-regulation of enzymes dedicated to detoxification of methylglyoxal and other reactive electrophiles.

Keywords: Bacteria; Gene Expression; GloA; Hypochlorous Acid; NemR; Oxidative Stress; Reactive Chlorine Species; Redox Regulation; Transcription Repressor.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Conserved Sequence
  • Cysteine / chemistry
  • DNA, Bacterial / chemistry
  • Disinfectants / pharmacology
  • Escherichia coli / drug effects
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / physiology*
  • Gene Expression Regulation, Bacterial / drug effects*
  • Hypochlorous Acid / pharmacology*
  • Models, Molecular
  • Molecular Sequence Data
  • Oxidants / pharmacology*
  • Oxidation-Reduction
  • Protein Binding / drug effects
  • Protein Structure, Secondary
  • Transcription Factors / chemistry
  • Transcription Factors / physiology*

Substances

  • DNA, Bacterial
  • Disinfectants
  • Escherichia coli Proteins
  • NemR protein, E coli
  • Oxidants
  • Transcription Factors
  • Hypochlorous Acid
  • Cysteine