Projects
1) Cell cycle regulation in Caulobacter crescentus.
We are interested in understanding the molecular intricacy of cell cycle regulation in Caulobacter using genetics, genomics and biochemical tools for the analysis of global regulation of genes' expression.
More specifically we are now focusing on:
a. We study the epigenetic switch GcrA/CcrM (based on Fioravanti et al., 2013, PLOS Genetics). We are using a combination of genomic approaches (RNAseq, CHIpseq), biochemistry (In vitro transcription, EMSA, DnaseI foot printing) and cell biology (FISH, see figure below) in order to understand this remarkable regulation. Here below an example of a GcrA-CcrM controlled gene that shows asymmetrical transcription (FISH) of the two copies of the gene during S-phase. (Hanna Bismuth)
B. NEW RESEARCH LINE: Are sRNAs playing an important role in Caulobacter? In collaboration with Eric Massé in Sherbrooke (Canada) and Maude Guiller in Paris we are exploring this layer of regulation.
(Wanassa Beroual)
(From Beroual et al., 2018, Frontiers in Genetics)
c. We are also studying the master regulator of cell cycle CtrA phosphorylation (Biondi et al., 20106, Nature). We recently developed a FRET-based biosensor able to detect CtrA-P levels in vivo (see below).
2) Cell cycle regulation in Sinorhizobium meliloti.
We believe that new discoveries about cell cycle can arise from the comparison between equivalent systems. We have been studying the regulation of cell cycle in the symbiotic alphaproteobacterium Sinorhizobium meliloti.
In particular:
a. We have characterized the DivK module (Pini et al., 2013, Mol Micro) and the master regulator CtrA (Pini et al., 2015, PLOS Genetics). New projects are now focused on GcrA/CcrM and new meliloti-specific cell cycle regulators.
b. We are very interested in the relationship between cell cycle and symbiosis: in particular we identified the potential role of CtrA in the differentiation. Systematic investigation of symbiotic behavior of cell cycle regulators is being performed by plant infection experiments. Moreover genetic screening of mutants resistant to plant peptides are ongoing. (Shuanghong Xue and Maeva Doudement)