The role of glyoxalase I in the detoxification of methylglyoxal and in the activation of the KefB K+ efflux system in Escherichia coli

M J MacLean, L S Ness, Gail Patricia Ferguson, Ian Rylance Booth

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The glyoxalase I gene (gloA) of Escherichia coli has been cloned and used to create a null mutant. Cells overexpressing glyoxalase I exhibit enhanced tolerance of methylglyoxal (MG) and exhibit elevated rates of detoxification, although the increase is not stoichiometric with the change in enzyme activity. Potassium efflux via KefB is also enhanced in the overexpressing strain. Analysis of the physiology of the mutant has revealed that growth and viability are quite normal, unless the cell is challenged with MG either added exogenously or synthesized by the cells. The mutant strain has a low rate of detoxification of MG, and cells rapidly lose viability when exposed to this electrophile. Activation of KefB and KefC is diminished in the absence of functional glyoxalase I. These data suggest that the glutathione-dependent glyoxalase I is the dominant detoxification pathway for MG in E. coli and that the product of glyoxalase I activity, S-lactoylglutathione, is the activator of KefB and KefC.
Original languageEnglish
Pages (from-to)563-571
Number of pages9
JournalMolecular Microbiology
Issue number3
Publication statusPublished - 1 Feb 1998



  • Antiporters
  • Bacterial Proteins
  • Cloning, Molecular
  • Escherichia coli
  • Escherichia coli Proteins
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial
  • Glutathione
  • Lactoylglutathione Lyase
  • Potassium
  • Potassium Channels
  • Potassium-Hydrogen Antiporters
  • Pyruvaldehyde

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