Each time budding yeast divide they ensure that both the mother and daughter cell inherit a vacuole. Because budding yeast divide asymmetrically by budding, the vacuole must be actively transported into the bud. As the mother cell begins budding, a tubular and vesicular segregation structure forms which is transported into the bud by the myosin V motor, Myo2, bound to the vacuole-specific myosin receptor Vac17. Upon arriving in the bud the segregation structure is resolved to found the daughter vacuole. The mechanism that regulates segregation structure resolution in a spatially dependent manner is unknown. Directionality in vacuole transport is ensured by the bud-specific degradation of Vac17. It has been proposed that bud-specific degradation of Vac17 is promoted by proteins localized to, or activated solely in, the bud. The p21-activated kinases (PAK) Cla4 and Ste20 are localized to and activated in the bud. Here I report that Cla4 localized to the segregation structure just prior to segregation structure resolution. Cells lacking PAK function failed to resolve the segregation structure. Overexpression of either Cla4 or Ste20 inhibited vacuole inheritance and this inhibition was suppressed by the expression of non-degradable VAC17. Finally, PAK activity was required for Vac17 degradation in late-M and CLA4 overexpression promoted Vac17 degradation. I propose that Cla4 and Ste20 are bud-specific proteins that promote segregation structure resolution and degradation of Vac17.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-03262008-105213 |
| Date | 26 March 2008 |
| Creators | Bartholomew, Clinton Ron |
| Contributors | Kathleen L. Gould, James R. Goldenring, Todd R. Graham, Christopher F.J. Hardy |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-03262008-105213/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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