Cell division is one of the fundamental processes that allows the proliferation of both prokaryotic and eukaryotic cells. Knowledge about bacterial cell division is essentially based on model organisms. In most bacteria, cell division takes place by a mechanism called binary fission. There are some exceptions to this mode of division, such as multiple fission or budding, although the mechanisms through which it occurs are totally unknown. Binary fission uses a mechanism based on the interaction between the protein homologous to eukaryotic tubulin, FtsZ, and the peptidoglycan biosynthesis machinery. FtsZ protein is almost universally conserved in bacteria, but it is also present in some archaea.
Planctomycetes are ubiquitous non-model bacteria belonging to the PVC superphylum (Planctomycetes, Verrucomicrobia, Chlamydiae). Among their most surprising characteristics is their endomembrane system, their lipid membrane composition or their cell division mechanisms.
All members of the phylum lack FtsZ, a central protein of the bacterial division machinery. Although the lower branching orders, "Candidatus Brocadiales" and Phycisphaerales, divide by apparently binary fission, the Planctomycetales order divides by asymmetric division, similar to budding. Additionally, some of the known essential proteins involved in bacterial cell division are absent or highly modified in the genomes of Planctomycetes, which could be related to the different modes of division that they use to proliferate. Recently, we have shown that some of these proteins that are normally essential, are not essential in some Planctomycetes, representing a unique case within bacteria. How Planctomycetes divide remains one of the biggest mysteries in Microbiology and could be related to the apparition of our own domain, the eukaryote.
The main interest of my group is focused on deciphering the molecular players responsible of cell division on Planctomycetes.