ftsZ mutations affecting cell division frequency, placement and morphology in Bacillus subtilis.

A key event in cytokinesis in bacteria is the assembly of the essential division protein FtsZ into ring-like structures at the nascent division site. FtsZ is the prokaryotic homologue of tubulin, and is found in nearly all bacteria. In vitro, FtsZ polymerizes in the presence of GTP to form higher-ordered polymers. FtsZ consists of two domains, with the GTP-binding site located in the N-terminal domain. The less-conserved C-terminal domain contains residues important for GTP hydrolysis, but its overall function is still unclear. This paper reports the development of a simple strategy to generate mutations in the essential division gene ftsZ. Nine novel and viable ftsZ mutants of Bacillus subtilis are described. Eight of the mutations would affect the C-terminus of FtsZ. The collection of mutants exhibits a range of morphological phenotypes, ranging from normal to highly filamentous cells; some produce minicells, or divide in a twisted configuration; one mutation has a temperature-sensitive effect specifically impairing sporulation. The sites of the amino acid changes generated by the mutations could be informative about FtsZ function and its protein-protein interactions.