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pubmed:abstractText |
Although the fission yeast Schizosaccharomyces pombe contains many of the ?-tubulin ring complex (?-TuRC)-specific proteins of the ?-tubulin complex (?-TuC), several questions about the organizational state and function of the fission yeast ?-TuC in vivo remain unresolved. Using 3×GFP-tagged ?-TuRC-specific proteins, we show here that ?-TuRC-specific proteins are present at all microtubule organizing centers in fission yeast and that association of ?-TuRC-specific proteins with the ?-tubulin small complex (?-TuSC) does not depend on Mto1, which is a key regulator of the ?-TuC. Through sensitive imaging in mto1? mutants, in which cytoplasmic microtubule nucleation is abolished, we unexpectedly found that ?-TuC incapable of nucleating microtubules can nevertheless associate with microtubule minus-ends in vivo. The presence of ?-TuC at microtubule ends is independent of ?-TuRC-specific proteins and strongly correlates with the stability of microtubule ends. Strikingly, microtubule bundles lacking ?-TuC at microtubule ends undergo extensive treadmilling in vivo, apparently induced by geometrical constraints on plus-end growth. Our results indicate that microtubule stabilization by the ?-TuC, independently of its nucleation function, is important for maintaining the organization and dynamic behavior of microtubule arrays in vivo.
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pubmed:affiliation |
Wellcome Trust Centre for Cell Biology, University of Edinburgh, Swann Building, Mayfield Road, Edinburgh EH9 3JR, UK.
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