Project description:Dam, the most described bacterial DNA-methyltransferase, is widespread in gamma-proteobacteria. Dam DNA methylation can play a role in various genes expression and is involved in pathogenicity of several bacterial species. In the entomopathogenic bacterium Photorhabdus luminescens, a dam ortholog was identified. Overexpression of dam in P. luminescens did not impair growth ability in vitro. In contrast, compared to a control strain harboring an empty plasmid, a significant decrease in motility was observed in the dam-overexpressing strain. In addition, the dam-overexpressing P. luminescens strain showed a delayed virulence compared to that of the control strain after injection in larvae of the lepidopteran Spodoptera littoralis. These results reveal that Dam plays a major role during P. luminescens insect infection.
Project description:A phoP mutant of the entomopathogenic bacterium P. luminescens is attenuated in virulence in insects and susceptible to antimicrobial peptides such as Polymyxin B. The first goal of this study is to compare transcriptomes of the phoP mutant and wild type strain to identify the PhoP regulon. (i) We first compared both strains grown in LB medium. (ii) As we know that low Mg conditions induce expression of PhoP-dependent genes, we also compared transcriptomes of the phoP and wild-type strain after growth in M9 low Mg and in M9 High Mg. To decipher the polymyxin B regulon, comparisons of transcriptomes of the wild type strain grown in LB medium with or without addition of polymyxin B were also performed
