Cell biology of cellular processes occurring across the bacterial cell wall

We are also exploring the cell biology of cellular processes occurring about across the bacterial cell wall and/or requiring cell wall remodeling, such as phage infection, genetic competence and sporulation. These are collaborative projects mainly funded by the ANR (French National Research Agency)

• Together with the lab of Paulo Tavares (i2BC, Gif-sur-Yvette, France), specialized in phage biology, we study the cell biology of phage infection. The biological system under study is the well-characterized bacteriophage SPP1 that infects B. subtilis. We discovered that during infection SPP1 builds spatially independent factories for viral genome replication and assembly of viral particles in the bacterial cytoplasm. Our collaboration aims to characterize molecular and cellular mechanisms underlying formation of these factories.
• In collaboration with the teams of Patrice Polard (LMGM, Toulouse) and Christophe Grangeasse (MMSB, Lyon), we are studying competence for genetic transformation of the human pathogen Streptococcus pneumoniae (the streptococcus). Our project focuses on the molecular characterization of a programmed cell growth arrest that occurs during competence, with the aim of understanding how the pneumococcus coordinates competence for genetic transformation with its life cycle.
• When facing severe nutritional stress, B. subtilis forms highly resistant endospores. The pathway to sporulation is probably the best-studied developmental program in bacteria. Yet, the function of many genes expressed during this process remains a mystery. In collaboration with Ciaran Condon (IPBC, Paris), we are trying to understand the role of an orphan ribonuclease that is expressed specifically in the mother cell during sporulation and may be part of a sporulation-specific degradosome-like complex with an additional role in spore coat assembly

Legend: Time-lapse microscopy of  SPP1 bacteriophage infection of B. subtilis cells.

Left, SPP1 phage DNA labeled with FROS. Right, phase contrast images.