DNA methylation and the Redox regulator OxyR: an epigenetic story in the entomopathogenic bacterium Xenorhabdus ?

Dam DNA methylation can modify the affinity of transcriptional regulators for their binding sitesand can therefore lead to the emergence of subpopulations, expressing or not some genes.Because these differential gene regulations can be transmitted to daughter cells, thisphenomenon is considered as an epigenetic mechanism.Xenorhabdus nematophila is an enterobacterium symbiotically associated to a soil nematodeand pathogenic for several insects. Its methylome analysis revealed that >99% of Adenines inGATC motifs of the genome are methylated. One of the rare unmethylated motifs is located in aputative OxyR-binding site in a promoter region. We constructed a Xenorhabdus oxyR mutant, and phenotypic analysis confirmed the role ofOxyR in adaptation to oxidative environments.We are now investigating if some genes are transcriptionally regulated by OxyR in a DNAmethylation-dependent manner.