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Title: Excessive Dynein Force In She1 Mutants Reveals Differences In Microtubule Anchorage In Budding Yeast
Authors: Bergman, Zane
Keywords: microtubules
spindle pole body
Issue Date: 31-Jan-2012
Abstract: Many microtubule functions, such as chromosome segregation and spindle orientation, depend on a stable anchor point in the cell. In the budding yeast, Saccharomyces cerevisiae, cytoplasmic microtubules (cMTs) are anchored at the spindle pole body (SPB), the equivalent of the microtubule organizing center. In she1[DELTA] mutants, I observed cMTs detach from the SPB and trace the periphery of the cell before depolymerizing. Disabling the dynein pathway rescued this phenotype, suggesting that this defect stems from She1's function in regulating dynein as opposed to a weakened SPB. It was observed that cMTs in she1[DELTA] mutants detach more readily early in the cell cycle, when the cMTS are anchored at the half-bridge, as opposed to after SPB duplication when cMTs are anchored at the outer plaque. This was confirmed by utilizing kar1-[DELTA]15 mutants that ablate cMT anchorage at the half-bridge. By visualizing GFP-tagged -tubulin complex proteins I determined that cMTs are pulled intact from the SBP and are subsequently depolymerized from their plus -ends. Similarly, the detachment phenotype could be rescued by expressing SPC72-KAR1 or SPC72-CNM67 fusion proteins that anchor cMTs solely at the half -bridge or outer iii plaque, respectively. Over-expressing SHE1 prevented the loading of dynactin components onto the plus-ends of cMTs, preventing proper spindle positioning by dynein. I found that She1 binds directly to MTs and that this binding may be the mechanism by which She1 controls dynein function. iv
Committee Chair: Huffaker, Tim Clark
Committee Co-Chair: Bretscher, Anthony Paul
Committee Member: Vogt, Volker M
Discipline: Biochemistry
Degree Name: Ph.D. of Biochemistry
Degree Level: Doctor of Philosophy
Degree Grantor: Cornell University
No Access Until: 2017-06-01
Appears in Collections:Cornell Theses and Dissertations

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