We have described recently a novel mechanism of regulation combining phase variation and attenuation of two pilus operons in Streptococcus gallolyticus . Phase variation occurs  by single-strand mispairing during replication due to the presence of repeats in the leader peptide located immediately upstream of the pilus operon. We wonder if the same mechanism is applicable to other bacterial genes.

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 (cyanobacteria collection), the ICAReB (human samples collection) and the Eukaryotic virus collection. Since January 2016, the CIP, has sequenced more than a thousand bacterial genomes and assembled them using the P2M pipeline. An initiative has been proposed by the CRBIP, in line with its new strategy of valorization, to annotate all genomes and make publicly available those from type strains with a private section for non-type strains that will be available to users on demand. To attain this objective, a long-term collaboration will be established between the CIP, the C3BI (Natalia Pietrosemoli's team) and the CRBIP that will start with a small project to do the draft annotation of the available bacterial genomes using the open source software, Prokka.

We want to look at the prevalence of protein composed of an orphan LytTR DNA-binding domain in diverse bacteria.

Streptococcus agalactiae (GBS) is a commensal gram-positive bacteria which asymptomatically colonize the genital and intestinal tract of healthy women. However, GBS is the leading cause of bacterial invasive infections in newborns in developed countries. The ability of GBS to succeed both as a commensal and a pathogen relies on a highly dynamic regulation of colonization and virulence related genes. The major regulator identified to date is the two-component system CovSR (Control of Virulence Sensor and Regulator). The transcription of almost 15% of the genome is dependent on CovR, but the genes directly regulated by CovR and the regulation of CovR-DNA binding by CovR-phosphorylation are ill-defined. To characterize the genome-wide CovR binding sites, we performed chromatin immunoprecipitation and sequencing (ChIP-Seq). Technically, we developed an epitope-tagged and functional form of CovR expressed under an inducible promoter. Quantitative PCR on ChIP samples (ChIP-qPCR) and small-scale footprint experiments revealed an enrichment of binding regions on specific promoters whose transcription are CovR-dependent. Sequencing (ChIP-seq) has been done to 1) characterize the landscape of CovR binding sites along the chromosome and to reveal the function of genes directly regulated by CovR; 2) to decipher the mechanism of regulation by performing the same experiment in strains with different level of CovR phosphorylation; and 3) to unravel an evolutionary strategy of genetic rewiring leading to the emergence of hypervirulent GBS strain by comparing the CovR direct regulon and the evolution of promoter sequences in different clinical stains.

The aim of this RNA-seq project is to characterize three transcriptional regulators of Streptococcus agalactiae, the main etiological agent of bacterial meningitis in neonate, and one transcriptional factor of Enterococcus faecalis, a second Gram-positive opportunistic pathogen.

This RNA-seq project aims to characterize the function of genes regulated by the master regulator of virulence in Group B Streptococcus.

Bacteria use two-component systems (TCS) to sense and adapt to their environment. The aim of this project is to characterize the regulatory network of each of the 20 TCS in the neonatal pathogen Streptococcus agalactiae.

Streptococcus gallolyticus sous espèce gallolyticus, autrefois dénommée Streptococcus bovis biotype I, est une bactérie de la flore intestinale qui constitue une cause émergente de septicémies et d’endocardites chez les personnes âgées. Depuis plus de 50 ans, les études épidémiologiques indiquent l’existence d’une forte association entre les infections invasives à S. gallolyticus et le CCR (cancer colorectal) (Pasquereau-Kotula et al., 2018). Néanmoins, le rôle exact de S.gallolyticus dans le développement du cancer colorectal n'est toujours pas déterminé. L’objectif principal de ce projet de recherche est de mieux comprendre le rôle de S. gallolyticus dans les CCR. Pour vérifier le rôle du S. gallolyticus dans le dévalement du CCR on a utilisé un modèle de cancer colorectal chez la souris (A/J + AOM). Grace à ce model o a peux démonter que S. gallolyticus accélère la tumorigenèse. Pour essayer de trouver un mechanism responsable de ce effect nous avons réalisé un protéome et un phosphoprotéome complets sur des tissus de souris colonisés par bactérie contrôle ou S. gallolyticus. L'analyse des changements dans le total et le phospho protéome aidera à mettre en évidence le mécanisme pertinent de la cancérogenèse induite par le S. gallolyticus.