Date of Award
Doctor of Philosophy (PhD)
Kin1 and Kin2 (Kin1/2), the S. cerevisiae orthologs of the mammalian microtubule affinity-regulating kinases (MARKs), regulate a variety of important cellular functions, including exocytosis and the unfolded protein response (UPR). In this study, I examined the regulation of Kin1/2 kinase activity and localization, which are poorly understood. I determined the impact on Kin1/2 of interaction with Bud14, a regulatory subunit of the phosphatase Glc7, the budding yeast ortholog of PP1. Kin1/2 localization to sites of polarized growth was completely dependent on interaction with Bud14, although Kin1/2 kinase activity was not dependent on Bud14. I also examined the impact of the kinase-associated 1 (KA1) domain on both the kinase activity and localization of Kin1/2. Mutation of the KA1 domain had a partial effect on Kin1/2 localization. The KA1 domain also autoinhibits Kin1/2 catalytic activity, and mutation of the KA1 domain increases Kin1/2 activity nearly ten-fold. Kin1/2 kinase activity is also profoundly impacted by activation loop phosphorylation of a conserved threonine residue, which increases Kin1/2 kinase activity by 20-fold. I found that the protein kinases Elm1, Sak1 and Tos3, which activate related kinases, are responsible for Kin1/2 activation loop phosphorylation. The level of kinase activity, but not localization, is vital for Kin1/2 function in the unfolded protein response. Taken together, these results further elucidate the mechanisms controlling cellular Kin1/2 activity and localization.
Weise, Keith Aaron, "Intermolecular and intramolecular interactions controlling the localization and activity of the yeast kinases Kin1 and Kin2" (2021). Yale Graduate School of Arts and Sciences Dissertations. 128.