How do protein kinases regulate cellular processes in Bacillus subtilis ?

Protein phosphorylation is a ubiquitous post-translational modification involved in cellular regulation in all forms of life. In a wide array of bacterial species, it was shown that Serine Threonine Kinase Proteins (STKPs) are implicated in many bacterial processes comprising central metabolism, sporulation, cell shape, and virulence... In addition, site-specific phosphoproteomic studies led to the publication of long lists of bacterial proteins phosphorylated on serine and threonine residues, suggesting that much more remains to be discovered concerning the regulatory potential of these enzymes in various cellular processes. Over the last years, several proteins, including cell division proteins as well as some peptidoglycan precursor-synthetizing or hydrolyzing enzymes etc…, have been shown to be phosphorylated in vitro or in vivo on serine or threonine residues by STKPs in different bacterial species. In addition, recent data have shown that STKPs play an important role to satisfy the different modes of cell division, the diversity of bacterial cell shapes and the developmental behavior. We are investigating the regulatory role of protein phosphorylation in the model bacterium Bacillus subtilis and we are studying how protein kinases regulate growth, division, morphogenesis etc…

Identification of genes involved in morphogenesis, division and chromosome dynamics under several metabolic conditions in Bacillus subtilis

Cellular processes in bacteria, like division, morphogenesis and chromosome dynamics are spatially and temporally controlled along the cell cycle. Importantly, these cellular processes are highly coordinated with metabolism to ensure the production of viable progeny. We are investigating how cells link essential cellular processes and nutrient availability. For that we have chosen two approaches. The first one is a candidate approach. We are deciphering the role of genes of unknown function linked to genes involved in metabolism. The second one is a genomic-scale approach. For that, we screen a B. subtilis library of single-gene mutants to identify those that present defects in morphology, division or chromosome dynamics only in a subset of metabolic conditions. For that, each mutant is evaluated at the single-cell level in four different carbon-source conditions with a homemade high-content screening. All the mutants that exhibited cellular defects in a culture medium dependent manner are studied to understand their role in morphogenesis, division and chromosome dynamics in B. subtilis.