A conserved oscillatory system that positions the divisome in Archaea.

Precise placement of the cell division machinery is essential for cell division in most organisms, yet the mechanisms responsible for this process vary substantially across the domains of life. In Eukaryotes, cell division is primarily driven by ESCRT-based systems, while many Bacteria rely on the Min system to ensure accurate positioning of the division septum. By contrast, the mechanisms by which Archaea spatially regulate divisome assembly remain largely unknown. Here, we identify a three-protein system, which we term divisome positioning proteins A, B and C (DipA, DipB and DipC) that is essential for correct divisome positioning in Haloferax volcanii. Deletion of any dip gene results in mislocalization of cell division proteins and the formation of abundant minicells, similar to Min defects in bacteria. Furthermore, we show that all three Dip proteins undergo pole-to-pole oscillation, and that DipB and DipC assemble into ring-like structures at midcell. Biochemical analyses demonstrate that DipA is a membrane binding GTPase whose association with the membrane is disrupted by DipB. Notably, Dip homologues are widely conserved across diverse archaeal lineages that employ FtsZ-based division, indicating that the Dip system is a broadly distributed key regulator of FtsZ-based cell division in Archaea. Despite its striking functional similarities to the bacterial Min system, the Dip system is entirely unrelated at the sequence level, representing a compelling example of convergent evolution of oscillatory spatial regulators in distinct domains of life.