SRA

Bacterial response to nitric oxide (NO) is of major importance for bacterial survival, as NO stress is a main actor of the eukaryote immune response. Several pathogenic bacteria have developed gene regulation systems involved in detoxification and in repairing the damages caused by NO. However, bacterial mechanisms of NO resistance are poorly described for Gram positive bacteria and especially Bacillus cereus. This food born and opportunistic pathogen does not have the common weapon against NO described in other pathogenic or non-pathogenic bacteria, such as the transcriptional regulators norR and nsrR, nor NO reductases. Using a transcriptomic approach, we investigated the mechanisms used by B. cereus to fight against NO stress. A cluster of 6 genes was identified to be particularly overexpressed in the early response to NO stress. This cluster contains an iron-sulphur cluster repair enzyme, a nitrite reductase and three enzymes involved in siroheme biosynthesis. We show a co-expression and a close genetic localization implying a functional link between those genes. This cluster may play a pivotal role in the defence mechanisms used by B. cereus to fight against NO stress during infection. Overall design: Impact of NO on B. cereus gene expression