In Schizosaccharomyces pombe cytokinesis requires assembly and constriction of an actomyosin-based contractile ring (CR). Nucleation of F-actin for the CR requires a single essential formin, Cdc12, that localizes to the cell middle upon mitotic onset. The molecular mechanisms dictating its divison site targeting during cytokinesis are unknown. We defined that a Cdc12 N-terminal motif directly binds the F-BAR domain of the scaffolding protein Cdc15 and this interaction is controlled by Cdk1 phosphorylation of Cdc12. Phosphorylation of Cdc12 inhibits binding to the F-BAR Cdc15. cdc12 alleles that cannot bind Cdc15 or with all six Cdk1 sites mutated to phospho-mimetic residues show reduced Cdc12 cell division site accumulation and delayed CR formation. Thus Cdk1 phosphorylation of Cdc12 antagonizes its interaction with Cdc15 and its division site localization, consistent with a general role for Cdk1 in inhibiting cytokinesis until chromosome segregation is complete.
The CR is physically linked to the plasma membrane (PM). Cells lacking efr3, which encodes a conserved PM scaffold for the phosphatidylinositol 4-kinase Stt4, build CRs that can slide away from the cell middle in a myosin-V-dependent manner. The Efr3-dependent CR anchoring mechanism is distinct from previously reported pathways dependent on the F-BAR protein Cdc15 and paxillin. In efr3รข, the concentrations of several membrane-binding proteins were reduced in the CR and/or on the PM. Our results suggest that proper PM lipid composition is important to stabilize the central position of the CR and resist myosin V-based forces to promote the fidelity of cell division.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-08102017-152412 |
| Date | 11 August 2017 |
| Creators | Willet, Alaina Hollister |
| Contributors | Kathleen Gould, Irina Kaverina, Matthew Tyska, Ryoma Ohi, Alissa Weaver |
| 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-08102017-152412/ |
| Rights | restrictsix, 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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