Bridging the lipid divide: archaeal ESCRT-III binds phosphoinositol and polarises the cytokinetic membrane

All cells remodel their membranes to divide. The highly conserved ESCRT-III system forms contractile polymers which, through direct interactions with membrane lipids, remodel membranes across the tree of life. In exploring how ESCRT-III divides the chemically and structurally unique archaeal membrane, we reveal that the homologue CdvB1 is required for the establishment of a distinct membrane domain within the division bridge of Sulfolobus acidocaldarius , associated with an accumulation of membrane-spanning inositol phosphate lipids. We show that CdvB1 associates with phosphoinositides in vitro and that this interaction aids cytokinesis in vivo . Together, we suggest that although eukaryotes inherited their membrane lipids from bacteria during eukaryogenesis, key features of the ESCRT-III:membrane interface that allow these polymers to bind, organise, and remodel eukaryotic membranes, may originate in archaea.