The cyclin-dependent kinase Cdk1 directly regulates vacuole inheritance

In budding yeast, vacuole inheritance is tightly coordinated with the cell cycle. The movement of vacuoles and several other organelles is actin-based and is mediated by interaction between the yeast myosin V motor Myo2 and organelle-specific adaptors. Myo2 binds to vacuoles via the adaptor protein Vac17, which binds to the vacuole membrane protein Vac8. Here we show that the yeast cyclin-dependent kinase Cdk1 phosphorylates Vac17 and that phosphorylation of Vac17 parallels cell cycle-dependent movement of the vacuole. Substitution of the Cdk1 sites in Vac17 decreases its interaction with Myo2 and causes a partial defect in vacuole inheritance. This defect is enhanced in the presence of Myo2 with mutated phosphorylation sites. Thus, Cdk1 appears to control the timing of vacuole movement. The presence of multiple predicted Cdk1 sites in other organelle-specific myosin V adaptors suggests that the inheritance of other cytoplasmic organelles may be regulated by a similar mechanism.