Coexistence of tubulins and ftsZ in different Prosthecobacter species.

Prosthecobacter, one of the few cultivable representatives of the bacterial phylum Verrucomicrobia, is of increasing interest to the scientific community due to the presence of tubulin genes in its genome and the apparent absence of the bacterial homologue FtsZ that is normally involved in prokaryotic cell division. These findings suggested the possibility of a vicarious takeover of the FtsZ function through these novel tubulins and opened new scenarios on the possible evolution of bacterial cytoskeleton and cell division. In the present manuscript, we report the characterization of ftsZ and ftsA homologues in different Prosthecobacter species that also possess tubulin genes. Based on these findings, we propose an FtsZ-based cell division mechanism in Verrucomicrobia. The analysis of available genome data of Verrucomicrobia suggests that tubulins are not a feature common to all members of this phylum. Therefore, it can be assumed that Prosthecobacter acquired tubulins through horizontal gene transfer. The functional role of tubulins in Prosthecobacter remains enigmatic.