Transposon-Directed Insertion-Site Sequencing Reveals Glycolysis Gene gpmA as Part of the H 2 O 2 Defense Mechanisms in Escherichia coli .

Hydrogen peroxide (H 2 O 2 ) is a common effector of defense mechanisms against pathogenic infections. However, bacterial factors involved in H 2 O 2 tolerance remain unclear. Here we used transposon-directed insertion-site sequencing (TraDIS), a technique allowing the screening of the whole genome, to identify genes implicated in H 2 O 2 tolerance in Escherichia coli . Our TraDIS analysis identified 10 mutants with fitness defect upon H 2 O 2 exposure, among which previously H 2 O 2 -associated genes ( oxyR , dps , dksA , rpoS , hfq and polA ) and other genes with no known association with H 2 O 2 tolerance in E. coli ( corA , rbsR , nhaA and gpmA ). This is the first description of the impact of gpmA , a gene involved in glycolysis, on the susceptibility of E. coli to H 2 O 2 . Indeed, confirmatory experiments showed that the deletion of gpmA led to a specific hypersensitivity to H 2 O 2 comparable to the deletion of the major H 2 O 2 scavenger gene katG . This hypersensitivity was not due to an alteration of catalase function and was independent of the carbon source or the presence of oxygen. Transcription of gpmA was upregulated under H 2 O 2 exposure, highlighting its role under oxidative stress. In summary, our TraDIS approach identified gpmA as a member of the oxidative stress defense mechanism in E. coli .