Regulation of Cytokinesis in Budding Yeast by Kinase Dbf2

This research focuses on cytokinesis in budding yeast, specifically how Dbf2 is recruited to the bud neck of a cell undergoing cytokinesis and if the kinase activity of Dbf2 is required for cytokinesis. Dbf2 is a kinase in the mitotic exit network (MEN) that moves from the spindle pole body to the bud neck in late mitosis in order to be in position to possibly regulate actomyosin ring contraction. The main question for this research was whether or not Dbf2 could localize with no actin ring present during cytokinesis. Dbf2 was tagged with the HA epitope in a yeast strain in which actin ring formation is prevented by addition of glucose. Immunofluorescence of cells under control conditions and when no actin ring is formed showed that Dbf2 does not require actin to localize to the bud neck. It was found that a dbf2-2 dbf20Δ with a kinase-dead mutant Dbf2 allele strain exhibited cytokinesis defects at the non-permissive temperature, demonstrating that Dbf2 kinase activity is required for cytokinesis