Microtubule stabilization in vivo by nucleation-incompetent ?-tubulin complex.

ABSTRACT: 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.

SUBMITTER: Anders A 

PROVIDER: S-EPMC3065382 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature