Whi5 regulation by site specific CDK-phosphorylation in Saccharomyces cerevisiae.
The Whi5 transcriptional repressor is a negative regulator of G1 cell cycle progression in Saccharomyces cerevisiae and is functionally equivalent to the Retinoblastoma (Rb) tumor suppressor protein in mammals. In early G1, Whi5 binds to and inhibits SBF (Swi4/Swi6) transcriptional complexes. At Sta...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2009-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC2627923?pdf=render |
| _version_ | 1818254813059612672 |
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| author | Michelle V Wagner Marcus B Smolka Rob A M de Bruin Huilin Zhou Curt Wittenberg Steven F Dowdy |
| author_facet | Michelle V Wagner Marcus B Smolka Rob A M de Bruin Huilin Zhou Curt Wittenberg Steven F Dowdy |
| author_sort | Michelle V Wagner |
| collection | DOAJ |
| description | The Whi5 transcriptional repressor is a negative regulator of G1 cell cycle progression in Saccharomyces cerevisiae and is functionally equivalent to the Retinoblastoma (Rb) tumor suppressor protein in mammals. In early G1, Whi5 binds to and inhibits SBF (Swi4/Swi6) transcriptional complexes. At Start, Cln:Cdc28 kinases phosphorylate and inactivate Whi5, causing its dissociation from SBF promoters and nuclear export, allowing activation of SBF transcription and entry into late G1. In an analysis of Whi5 phosphorylation, we found that 10 of the 12 putative CDK phosphorylation sites on Whi5 were occupied in vivo in asynchronously growing cells. In addition, we identified 6 non-CDK Whi5 phosphorylation sites. Whi5 CDK and non-CDK phosphorylation mutants were functional and able to rescue the small cell size of whi5Delta cells. However, the Whi5 CDK mutant with all 12 putative CDK sites changed to alanine causes a dramatic cell cycle phenotype when expressed with a Swi6 CDK phosphorylation mutant. Mutational analysis of Whi5 determined that only four C-terminal CDK sites were necessary and sufficient for Whi5 inactivation when Swi6 CDK sites were also mutated. Although these four Whi5 CDK sites do not wholly determine Whi5 nuclear export, they do impact regulation of cell size. Taken together, these observations begin to dissect the regulatory role of specific phosphorylation sites on Whi5. |
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| format | Article |
| id | doaj.art-91f47ffab85c4cb5a6a1668e3bab7c94 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-12T17:01:55Z |
| publishDate | 2009-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-91f47ffab85c4cb5a6a1668e3bab7c942022-12-22T00:18:07ZengPublic Library of Science (PLoS)PLoS ONE1932-62032009-01-0141e430010.1371/journal.pone.0004300Whi5 regulation by site specific CDK-phosphorylation in Saccharomyces cerevisiae.Michelle V WagnerMarcus B SmolkaRob A M de BruinHuilin ZhouCurt WittenbergSteven F DowdyThe Whi5 transcriptional repressor is a negative regulator of G1 cell cycle progression in Saccharomyces cerevisiae and is functionally equivalent to the Retinoblastoma (Rb) tumor suppressor protein in mammals. In early G1, Whi5 binds to and inhibits SBF (Swi4/Swi6) transcriptional complexes. At Start, Cln:Cdc28 kinases phosphorylate and inactivate Whi5, causing its dissociation from SBF promoters and nuclear export, allowing activation of SBF transcription and entry into late G1. In an analysis of Whi5 phosphorylation, we found that 10 of the 12 putative CDK phosphorylation sites on Whi5 were occupied in vivo in asynchronously growing cells. In addition, we identified 6 non-CDK Whi5 phosphorylation sites. Whi5 CDK and non-CDK phosphorylation mutants were functional and able to rescue the small cell size of whi5Delta cells. However, the Whi5 CDK mutant with all 12 putative CDK sites changed to alanine causes a dramatic cell cycle phenotype when expressed with a Swi6 CDK phosphorylation mutant. Mutational analysis of Whi5 determined that only four C-terminal CDK sites were necessary and sufficient for Whi5 inactivation when Swi6 CDK sites were also mutated. Although these four Whi5 CDK sites do not wholly determine Whi5 nuclear export, they do impact regulation of cell size. Taken together, these observations begin to dissect the regulatory role of specific phosphorylation sites on Whi5.http://europepmc.org/articles/PMC2627923?pdf=render |
| spellingShingle | Michelle V Wagner Marcus B Smolka Rob A M de Bruin Huilin Zhou Curt Wittenberg Steven F Dowdy Whi5 regulation by site specific CDK-phosphorylation in Saccharomyces cerevisiae. PLoS ONE |
| title | Whi5 regulation by site specific CDK-phosphorylation in Saccharomyces cerevisiae. |
| title_full | Whi5 regulation by site specific CDK-phosphorylation in Saccharomyces cerevisiae. |
| title_fullStr | Whi5 regulation by site specific CDK-phosphorylation in Saccharomyces cerevisiae. |
| title_full_unstemmed | Whi5 regulation by site specific CDK-phosphorylation in Saccharomyces cerevisiae. |
| title_short | Whi5 regulation by site specific CDK-phosphorylation in Saccharomyces cerevisiae. |
| title_sort | whi5 regulation by site specific cdk phosphorylation in saccharomyces cerevisiae |
| url | http://europepmc.org/articles/PMC2627923?pdf=render |
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