Distinct mechanisms of multisite phosphorylation of the transcriptional inhibitor Whi5 regulate the budding yeast cell cycle
Abstract/Contents
- Abstract
- Budding yeast cells link their rate of division to growth via the transcriptional inhibitor Whi5. Cell growth dilutes, and thereby partially inactivates, Whi5, allowing the expression of two cyclins, Cln1 and Cln2. Cln1 and Cln2, in complex with cyclin-dependent kinase (Cdk1), further inactivate Whi5, completing a positive feedback loop that drives cells into S-phase by inducing expression of hundreds of genes. An additional cyclin-Cdk1 complex, Cln3-Cdk1, has been thought to contribute to the initial inactivation of Whi5 through phosphorylation. Using phos-tag SDS-PAGE to assay the phosphorylation state of Whi5 in vivo, we show that, although Cdk1 activity is required at S-phase entry, Whi5 phosphorylation during G1 does not require Cdk1. We identify the specific residues on Whi5 that are phosphorylated during G1 and show that their ablation has a moderate effect on cell cycle progression, as assayed by cell size. We also find that two of these phosphosites match the consensus motif for PKA, suggesting a possible additional Whi5 regulatory mechanism. We show that rapid Whi5 phosphorylation at S-phase entry depends on the phospho-threonine binding activity of the cyclin-Cdk1 subunit Cks1. Finally, we find that blocking Cks1 binding to Whi5 phospho-threonines yields a size phenotype equivalent to blocking all Whi5 phosphorylation by cyclin-Cdk1. This suggests that Cks1 binding to Whi5 phospho-threonines is essential to the function of Whi5 phosphorylation by cyclin-Cdk1.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2017 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Turner, Jonathan Joseph |
|---|---|
| Associated with | Stanford University, Department of Biology. |
| Primary advisor | Skotheim, Jan, 1977- |
| Thesis advisor | Skotheim, Jan, 1977- |
| Thesis advisor | Stearns, Tim |
| Thesis advisor | Straight, Aaron, 1966- |
| Advisor | Stearns, Tim |
| Advisor | Straight, Aaron, 1966- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Jonathan Joseph Turner. |
|---|---|
| Note | Submitted to the Department of Biology. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2017. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2017 by Jonathan Joseph Turner
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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