Orateur
Description
Streptomyces are gram-positive, multicellular, filamentous aerobic bacteria characterized by a large linear chromosome divided into a central region harboring cores genes and two extremities enriched in genomic islands (GIs) such as the specialized metabolite biosynthetic gene clusters (SMBGCs) and prophage. Nevertheless, the majority of GIs remain transcriptionally silent over growth under laboratory conditions. Interestingly, a stress condition (HT medium) was recently found to be associated with awakening of a prophage. Characterizing Streptomyces physiology and chromosome conformation in this growth condition and identifying the cellular machineries involved in the regulation of prophage expression are hot topics to explore. First, we have identified a variant of HT medium named BM (Bacteriophage production Medium) in which the phage production is optimal and we demonstrated that the production of this phage mediates multicellular bacteria dispersal in response to metabolic stress. Moreover, we studied the effect of the prophage on chromosome conformation and the results have shown that phage dormancy is associated with a specific DNA contact pattern, named condensate, and this motif disappears when the phage is produced. In addition, by performing the Chromatin ImmunoPrecipitation followed by sequencing (ChIP-seq), we found out that Lsr2A, which is a nucleoid associated protein (NAP) that acts as xenogeneic silencer, targets the prophage and this reflects the involvement of this NAP in the prophage modulation. The project is ongoing and the effect of prophage on chromosome conformation and gene expression as well as the role of other NAPs in the chromatin dynamics of Streptomyces over growth are currently being investigated.
