Escherichia coli cytochrome c peroxidase is a respiratory oxidase that enables the use of hydrogen peroxide as a terminal electron acceptor

Maryam Khademian, James A. Imlay

Research output: Contribution to journalArticlepeer-review

Abstract

Microbial cytochrome c peroxidases (Ccp) have been studied for 75 years, but their physiological roles are unclear. Ccps are located in the periplasms of bacteria and the mitochondrial intermembrane spaces of fungi. In this study, Ccp is demonstrated to be a significant degrader of hydrogen peroxide in anoxic Escherichia coli. Intriguingly, ccp transcription requires both the presence of H2O2 and the absence of O2. Experiments show that Ccp lacks enough activity to shield the cytoplasm from exogenous H2O2. However, it receives electrons from the quinone pool, and its flux rate approximates flow to other anaerobic electron acceptors. Indeed, Ccp enabled E. coli to grow on a nonfermentable carbon source when H2O2 was supplied. Salmonella behaved similarly. This role rationalizes ccp repression in oxic environments. We speculate that micromolar H2O2 is created both biologically and abiotically at natural oxic/anoxic interfaces. The OxyR response appears to exploit this H2O2 as a terminal oxidant while simultaneously defending the cell against its toxicity.

Original languageEnglish (US)
Pages (from-to)E6922-E6931
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number33
DOIs
StatePublished - Aug 15 2017

Keywords

  • Anaerobic respiration
  • Oxidative stress
  • OxyR

ASJC Scopus subject areas

  • General

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