F-BAR domain protein Rga7 collaborates with Cdc15 and Imp2 to ensure proper cytokinesis in fission yeast

Abstract

F-BAR domain proteins act as linkers between the cell cortex and cytoskeleton and are involved in membrane binding and bending. Rga7 is one of the seven F-BAR proteins present in fission yeast. In addition to the F-BAR domain at the N-terminal region, Rga7 possesses a Rho-GAP domain at its C-terminus. We show here that Rga7 is necessary to prevent contracting ring fragmentation and incorrect septum synthesis. Accordingly, cultures of cells lacking Rga7 contain a higher percentage of dividing cells and more frequent asymmetric or aberrant septa, which ultimately may cause cell death. Rga7 F-BAR domain is necessary for the protein localization to the division site and to the cell tips and also for the Rga7 roles in cytokinesis. In contrast, Rga7 GAP catalytic activity seems to be dispensable. Moreover, we demonstrate that Rga7 cooperates with the two F-BAR proteins Cdc15 and Imp2 to ensure proper cytokinesis. We have also detected association of Rga7 with Imp2, and its binding partners Fic1 and Pxl1. Altogether, our findings suggest that Rga7 forms part of a protein complex that coordinates late stages of cytokinesis