The archaeal division protein CdvB1 assembles into polymers that are depolymerized by CdvC

The Cdv proteins constitute the cell-division system of the Crenarchaea, in a protein machinery that is closely related to the ESCRT system of eukaryotes. The CdvB paralog CdvB1 is believed to play a major role in the constricting ring that is the central actor in cell division in the crenarchaea. Here, we present an in vitro study of purified CdvB1 from the crenarchaeon M. sedula with a combination of TEM imaging and biochemical assays. We show that CdvB1 self-assembles into filamentous polymers that are depolymerized by the action of the Vps4-homolog ATPase CdvC. Using liposome flotation assays, we show that CdvB1 binds to negatively charged lipid membranes and can be detached from the membrane by the action of CdvC. Interestingly, we find that the polymerization and the membrane binding are mutually exclusive properties of the protein. Our findings provide novel insight into one of the main components of the archaeal cell division machinery.