Bacterial cell division is a temporally and spatially regulated process coordinated by a multi-protein complex called the divisome. The assembly of the divisome is initiated and organized by a highly conserved bacterial protein, the bacterial tubulin homologue FtsZ, which polymerizes to form a dynamic ring structure (Z-ring) that marks the site of cell division. Following ring assembly, FtsZ recruits structural and accessory proteins in an ordered manner to form the functional cell division machinery and to build a new cell wall. The precise molecular mechanisms by which the assembly and regulation of the bacterial cell division machinery is achieved remains elusive, even in extensively studied model organisms such as Escherichia coli, Bacillus subtilis or Caulobacter crescentus. While genetic and biochemical techniques have identified many interactions amongst cell division proteins, the overall structure and dynamics of the divisome as a (large) multi-protein complex are still completely unknown. Furthermore, although the general scheme for divisome assembly and function seems to be widely conserved in bacteria, important species-specific differences exist – most likely to satisfy different cell morphologies, growth modes and cell wall composition. This is particularly true in Corynebacteriales, the suborder of Actinobacteria including important human pathogens such as Mycobacterium tuberculosis, Mycobacterium leprae and Corynebacterium diphtheriae. Corynebacteriales are Gram +ve diderm bacteria with a complex cell wall and a polar elongation mode. In this large phylum, many of the well characterized divisome regulators are missing from the genomes. Here I will present early divisome assembly mechanisms centred around SepF, the membrane anchor for FtsZ, and the only cell division-associated protein from Actinobacteria known to directly interact with the conserved C-terminal tail of FtsZ. I will also describe recent attempts to look for missing divisome members using mass-spec based interactomics.
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Institut Pasteur, Laboratoire Microbiologie Structurale
Early divisome assembly in Corynebacteriales: a mechanistic microbiology approach
Salle de réunion 142, bâtiment 210
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