Regulation of a formin complex by the microtubule plus end protein tea1p.
The plus ends of microtubules have been speculated to regulate the actin cytoskeleton for the proper positioning of sites of cell polarization and cytokinesis. In the fission yeast Schizosaccharomyces pombe, interphase microtubules and the kelch repeat protein tea1p regulate polarized cell growth. Here, we show that tea1p is directly deposited at cell tips by microtubule plus ends. Tea1p associates in large "polarisome" complexes with bud6p and for3p, a formin that assembles actin cables. Tea1p also interacts in a separate complex with the CLIP-170 protein tip1p, a microtubule plus end-binding protein that anchors tea1p to the microtubule plus end. Localization experiments suggest that tea1p and bud6p regulate formin distribution and actin cable assembly. Although single mutants still polarize, for3Deltabud6Deltatea1Delta triple-mutant cells lack polarity, indicating that these proteins contribute overlapping functions in cell polarization. Thus, these experiments begin to elucidate how microtubules contribute to the proper spatial regulation of actin assembly and polarized cell growth.
Feierbach
Becket
B
Department of Microbiology, Columbia University College of Physicians and Surgeons, 701 W. 168th St., New York, NY 10032, USA.
Verde
Fulvia
F
Chang
Fred
F
D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D016764:Cell Polarity / Q000235:genetics*; D000080865:Formins; D046911:Macromolecular Substances; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009363:Neoplasm Proteins; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000378:metabolism* / Q000648:ultrastructure; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*
C107727:BUD6 protein, S cerevisiae; C499541:Bud6 protein, S pombe; D018797:Cell Cycle Proteins; C444419:FOR3 protein, S pombe; D000080865:Formins; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C432671:Tea1 protein, S pombe; C076744:cytoplasmic linker protein 170