Escherichia coli has been the dominant organism to study cell division and its mode of division has therefore become the default. The increased genetic accessibility, cultivability of bacterial species and the fluorescent protein revolution have given access to other organisms that show quite some variation in their approach to binary fission. From these studies the question emerges whether the variation concerns only the preparation for division or also the core of the molecular mechanism.
Cell division in E. coli is initiated by the polymerization of the tubulin homolog FtsZ in a ring-like structure at mid cell. This ring recruits the proteins that are required for the synthesis of the septum during division. Binary fission requires the cell to define its middle, to know when to initiate division and to regulate the concerted invagination of the envelope with timely segregation of the chromosomes. This review discusses the various solutions Gram-negative (and some Gram-positive) species have found to reliably handle these three problems.
Prokaryotic cell division: flexible and diverse. (2013) Curr Opin Microbiol. pii: S1369-5274(13)00153-7. doi: 10.1016/j.mib.2013.09.002
Gram-negative rod-shaped bacteria have different approaches to position the cell division initiating Z-ring at the correct moment in their cell division cycle. The subsequent maturation into a functional division machine occurs in vastly different species in two steps with appreciable time in between these. The function of this time delay is unclear, but may partly be explained by competition for Lipid-II between proteins involved in length growth that interact directly with the Z-ring early in the maturation phase and the proteins involved in septum synthesis. A second possible activity of the early Z-ring might be the monitoring of or the active involvement in DNA segregation through proteins such as ZapA and ZapB/MatP and their homologues.