DNA adenine methyltransferase (Dam) overexpression impairs Photorhabdus luminescens motility and virulence. Photorhabdus laumondii subsp. laumondii TTO1

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. Overall design: Three independent RNA samples, each corresponding to a pool of total RNA extracted independently from 3 biological replicates cultures of: [1] TT01 (pBBR1MCS-5) grown in LB supplemented with gentamycine harvested in exponential phase (OD= 0.5). [2] TT01 (pBB-Dam) grown in LB supplemented with gentamycine harvested in exponential phase (OD= 0.5). Deep sequencing, performed using Illumina HiSeq 2000.