Involvement of the osrR gene in the hydrogen peroxide-mediated stress response of Corynebacterium glutamicum

A transcriptional profile of the H2O2-adapted Corynebacterium glutamicum HA strain reveals a list of upregulated regulatory genes. Among them, we selected ORF NCgl2298, designated osrR and analyzed its role in H2O2 adaptation. The osrR-deleted (Delta osrR) mutant had defective growth in minimal medium, which was even more pronounced in an osrR deletion mutant of an HA strain. The Delta osrR strain displayed increased sensitivity to H2O2. In addition to H2O2 sensitivity, the Delta osrR strain was found to be temperature-sensitive at 37 degrees C. 2D-PAGE analysis of the Delta osrR mutant found that MetE and several other proteins involved in redox metabolism were affected by the mutation. Accordingly, the NADPH/NADP(+) ratio of the Delta osrR strain (0.85) was much lower than that of the wild-type strain (2.01). In contrast, the NADH/NAD(+) ratio of the mutant (0.54) was considerably higher than that of the wild-type (0.21). Based on these findings, we propose that H2O2-detoxifying metabolic systems, excluding those involving catalase, are present in C. glutamicum and are regulated, in part, by osrR. (C) 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.