Kinase activity of ArcB from Escherichia coli is subject to regulation by both ubiquinone and demethylmenaquinone

PLoS One. 2013 Oct 7;8(10):e75412. doi: 10.1371/journal.pone.0075412. eCollection 2013.

Abstract

Expression of the catabolic network in Escherichia coli is predominantly regulated, via oxygen availability, by the two-component system ArcBA. It has been shown that the kinase activity of ArcB is controlled by the redox state of two critical pairs of cysteines in dimers of the ArcB sensory kinase. Among the cellular components that control the redox state of these cysteines of ArcB are the quinones from the cytoplasmic membrane of the cell, which function in 'respiratory' electron transfer. This study is an effort to understand how the redox state of the quinone pool(s) is sensed by the cell via the ArcB kinase. We report the relationship between growth, quinone content, ubiquinone redox state, the level of ArcA phosphorylation, and the level of ArcA-dependent gene expression, in a number of mutants of E. coli with specific alterations in their set of quinones, under a range of physiological conditions. Our results provide experimental evidence for a previously formulated hypothesis that not only ubiquinone, but also demethylmenaquinone, can inactivate kinase activity of ArcB. Also, in a mutant strain that only contains demethylmenaquinone, the extent of ArcA phosphorylation can be modulated by the oxygen supply rate, which shows that demethylmenaquinone can also inactivate ArcB in its oxidized form. Furthermore, in batch cultures of a strain that contains ubiquinone as its only quinone species, we observed that the ArcA phosphorylation level closely followed the redox state of the ubiquinone/ubiquinol pool, much more strictly than it does in the wild type strain. Therefore, at low rates of oxygen supply in the wild type strain, the activity of ArcB may be inhibited by demethylmenaquinone, in spite of the fact that the ubiquinones are present in the ubiquinol form.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Escherichia coli
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Gene Expression Regulation, Bacterial*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Oxidation-Reduction
  • Phosphorylation
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Signal Transduction / genetics
  • Ubiquinone / genetics
  • Ubiquinone / metabolism*
  • Vitamin K 2 / analogs & derivatives*
  • Vitamin K 2 / metabolism

Substances

  • Escherichia coli Proteins
  • Membrane Proteins
  • Vitamin K 2
  • Ubiquinone
  • demethylmenaquinone
  • Protein Kinases
  • arcB protein, E coli

Grants and funding

This work was supported by the SysMo-SUMO2 project and the Erasmus Mundus External 327 Cooperation Window (EMECW). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.