Spatiotemporal regulation of organelle transport by spindle position checkpoint kinase Kin4.

ABSTRACT

Asymmetric cell division in Saccharomyces cerevisiae involves Class V myosin-dependent transport of organelles along the polarised actin cytoskeleton to the emerging bud. Vac17 is the vacuole/lysosome-specific myosin receptor. Its timely breakdown terminates transport and results in the proper positioning of vacuoles in the bud. Vac17 breakdown is controlled by the bud-concentrated p21-activated kinase, Cla4, and the E3-Ubiquitin ligase, Dma1. We found that the spindle position checkpoint kinase, Kin4, and to a lesser extent its paralog Frk1, contribute to successful vacuole transport by preventing the premature breakdown of Vac17 by Cla4 and Dma1. Furthermore, Kin4 and Cla4 contribute to the regulation of peroxisome transport. We conclude that Kin4 acts antagonistically to the Cla4-/Dma1-pathway to coordinate spatiotemporal regulation of organelle transport.