Opposite Surfaces of the Cdc15 F-BAR Domain Create a Membrane Platform That Coordinates Cytoskeletal and Signaling Components for Cytokinesis

Cell Rep. 2020 Dec 22;33(12):108526. doi: 10.1016/j.celrep.2020.108526.

Abstract

Many eukaryotes assemble an actin- and myosin-based cytokinetic ring (CR) on the plasma membrane (PM) for cell division, but how it is anchored there remains unclear. In Schizosaccharomyces pombe, the F-BAR protein Cdc15 links the PM via its F-BAR domain to proteins in the CR's interior via its SH3 domain. However, Cdc15's F-BAR domain also directly binds formin Cdc12, suggesting that Cdc15 may polymerize a protein network directly adjacent to the membrane. Here, we determine that the F-BAR domain binds Cdc12 using residues on the face opposite its membrane-binding surface. These residues also bind paxillin-like Pxl1, promoting its recruitment with calcineurin to the CR. Mutation of these F-BAR domain residues results in a shallower CR, with components localizing ∼35% closer to the PM than in wild type, and aberrant CR constriction. Thus, F-BAR domains serve as oligomeric membrane-bound platforms that can modulate the architecture of an entire actin structure.

Keywords: F-BAR; F-actin; Pxl1; calcineurin; cytokinesis; cytokinetic ring; fPALM; fission yeast; paxillin; plasma membrane; structure.