Etude de la méthylation de l'ADN chez la bactérie pathogène d'insectes Photorhabdus luminescens.

par Amaury Payelleville

Projet de thèse en Mécanismes des Interactions parasitaires pathogènes et symbiotiques

Sous la direction de Julien Brillard et de Alain Givaudan.

Thèses en préparation à Montpellier , dans le cadre de GAIA - Biodiversité, Agriculture, Alimentation, Environnement, Terre, Eau , en partenariat avec DGIMI - Diversité, Génomes & Interactions Microorganismes-Insectes (laboratoire) et de Biologie intégrative des Interactions Bactéries - Insectes - Nématodes Entomopathogènes (BIBINE) (equipe de recherche) depuis le 01-10-2015 .


  • Résumé

    DNA methylation is known to be involved in gene expression. Dam is the most described prokaryotic DNA Adenine methyltransferase and is widespread among gammaproteobacteria. It plays a role in Salmonella or E. coli pathogenicity and influences expression of motility genes. Photorhabdus luminescens TT01 is an entomopathogenic bacterium symbiotically associated with a soil nematode of the genus Heterorhabditis. It enters in insect by natural orifices or cuticle and releases bacteria in hemolymph. P. luminescens is able to kill insects by septicemia. We studied the dam ortholog found in the genome of this bacterium and showed that it can complement an E. coli Dam mutant. After overexpression (~25X) of the dam gene in P. luminescens, a significant decrease in motility and a delayed lethal time 50 in pathogenicity in insect was observed compared to the control strain (harboring an empty plasmid). No differences were observed in growth or mutation frequency between dam overexpressing strain and control. The aim is now to correlate the observed phenotypes by a differential gene expression and a methylation pattern variation, using a transcriptome and methylome analysis. To go further, we will search if differences in gene expression are related to the whole bacterial population or only a part of it. If phenotypic heterogeneity is observed, we will search if Dam methylation plays a role in this phenomenon.

  • Titre traduit

    DNA methylation role in the insect pathogen bacterium Photorhabdus luminescens.


  • Résumé

    DNA methylation is known to be involved in gene expression. Dam is the most described prokaryotic DNA Adenine methyltransferase and is widespread among gammaproteobacteria. It plays a role in Salmonella or E. coli pathogenicity and influences expression of motility genes. Photorhabdus luminescens TT01 is an entomopathogenic bacterium symbiotically associated with a soil nematode of the genus Heterorhabditis. It enters in insect by natural orifices or cuticle and releases bacteria in hemolymph. P. luminescens is able to kill insects by septicemia. We studied the dam ortholog found in the genome of this bacterium and showed that it can complement an E. coli Dam mutant. After overexpression (~25X) of the dam gene in P. luminescens, a significant decrease in motility and a delayed lethal time 50 in pathogenicity in insect was observed compared to the control strain (harboring an empty plasmid). No differences were observed in growth or mutation frequency between dam overexpressing strain and control. The aim is now to correlate the observed phenotypes by a differential gene expression and a methylation pattern variation, using a transcriptome and methylome analysis. To go further, we will search if differences in gene expression are related to the whole bacterial population or only a part of it. If phenotypic heterogeneity is observed, we will search if Dam methylation plays a role in this phenomenon.