title: Constitutive dynein activity in She1 mutants reveals differences in microtubule attachment at the yeast spindle pole body.
abstract: The organization of microtubules is determined in most cells by a microtubule-organizing center, which nucleates microtubule assembly and anchors their minus ends. In Saccharomyces cerevisiae cells lacking She1, cytoplasmic microtubules detach from the spindle pole body at high rates. Increased rates of detachment depend on dynein activity, supporting previous evidence that She1 inhibits dynein. Detachment rates are higher in G1 than in metaphase cells, and we show that this is primarily due to differences in the strengths of microtubule attachment to the spindle pole body during these stages of the cell cycle. The minus ends of detached microtubules are stabilized by the presence of γ-tubulin and Spc72, a protein that tethers the γ-tubulin complex to the spindle pole body. A Spc72-Kar1 fusion protein suppresses detachment in G1 cells, indicating that the interaction between these two proteins is critical to microtubule anchoring. Overexpression of She1 inhibits the loading of dynactin components, but not dynein, onto microtubule plus ends. In addition, She1 binds directly to microtubules in vitro, so it may compete with dynactin for access to microtubules. Overall, these results indicate that inhibition of dynein activity by She1 is important to prevent excessive detachment of cytoplasmic microtubules, particularly in G1 cells.
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Zane J
authors.initials: ZJ
authors.lastname: Bergman
authors.forename: Xue
authors.initials: X
authors.lastname: Xia
authors.forename: I Alexandra
authors.initials: IA
authors.lastname: Amaro
authors.forename: Tim C
authors.initials: TC
authors.lastname: Huffaker
mesh_terms: D015153:Blotting, Western; D003593:Cytoplasm / Q000378:metabolism; D000072159:Dynactin Complex; D004398:Dyneins / Q000378:metabolism*; D016193:G1 Phase; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D022101:Microtubule-Organizing Center / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D009154:Mutation; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D024701:Myosin Type V / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism; D014404:Tubulin / Q000235:genetics / Q000378:metabolism
chemical_list: D000072159:Dynactin Complex; C074559:KAR1 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; C098732:Myo4 protein, S cerevisiae; D009687:Nuclear Proteins; C418484:SPC72 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014404:Tubulin; D049452:Green Fluorescent Proteins; D024701:Myosin Type V; D018995:Myosin Heavy Chains; D004398:Dyneins