Increasing evidence indicates that nucleoid spatiotemporal organization is crucial for bacterial physiology since these microorganism lack a compartmentalized nucleus. However, it is still unclear how gene order within the chromosome can influence cell physiology. In silico approaches have shown that genes involved in transcription and translation processes, in particular ribosomal protein (RP) genes, tend to be located near the replication origin (oriC) in fast-growing bacteria suggesting that such a positional bias might be an evolutionarily conserved growth-optimization strategy. Recently we systematically relocated a locus containing half of ribosomal protein genes (S10) to different genomic positions in Vibrio cholerae. These experiments revealed drastic differences in growth rate and infectivity within this isogenic strain set. We showed that genomic positioning of ribosomal protein genes is crucial for physiology by providing replication-dependent higher dosage in fast growing conditions. Therefore it might play a key role in genome evolution of bacterial species. We aim at observing how the genomic positioning of these genes would influence the evolution of Vibrio cholerae. To gain insight into the evolutionary consequences of relocating RP genes, we let evolve either the wild type or the most affected strains for 1000 generations in fast-growing conditions. NGS will be performed and analyzedon the evolved populations to understand the genetic changes responsible of the observed phenotypic changes.

Thanks to RNA-Seq experiments we identified  a new orphan DNA methylase (not associated with a restriction enzyme) that is highly upregulated in the presence of low concentrations of aminoglycosides in V. cholerae. The results allow us to consider a differential DNA methylation profile depending on the environment (with or without antibiotics), which can possibly correspond to a novel epigenetic control of the response.

The CRBIP, Centre de Ressources Biologiques de l’Institut Pasteur, is a structure created in 2001 that encompasses the Pasteurian culture collections: the CIP (bacteria collection), the PCC (cyanobact