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.