Diverse roles for a conserved DNA-methyltransferase in the entomopathogenic bacterium Xenorhabdus. undefined

In bacteria, DNA-methyltransferase are responsible for DNA methylation of specific motifs in the genome. This methylation usually occurs at a very high rate. In the present study, we studied the MTases encoding genes found in the entomopathogenic bacteria Xenorhabdus. Only one persistant MTase was identified in the various species of this genus. This MTase, also broadly conserved in numerous Gram-negative bacteria is called Dam for DNA-Adenine MTase. Methylome analysis confirmed that the GATC motifs recognized by Dam were methylated at a rate >99% in the studied strains. The observed enrichment of unmethylated motifs in putative promoter regions of the X. nematophila F1 strain suggests the possibility of epigenetic regulations. While only a limited number (n= 77) of unmethylated sites was identified, the overexpression of the Dam MTase presumably responsible for a few additional motifs to be methylated, was associated to impairement of major phenotypes, such as motility and hemolysis. Our results increase the knowledge on the diverse roles played by MTases in bacteria.