Microtubule capture by the cleavage apparatus is required for proper spindle positioning in yeast.
Cell division is the result of two major cytoskeletal events: partition of the chromatids by the mitotic spindle and cleavage of the cell by the cytokinetic apparatus. Spatial coordination of these events ensures that each daughter cell inherits a nucleus. Here we show that, in budding yeast, capture and shrinkage of astral microtubules at the bud neck is required to position the spindle relative to the cleavage apparatus. Capture required the septins and the microtubule-associated protein Kar9. Like Kar9-defective cells, cells lacking the septin ring failed to position their spindle correctly and showed an increased frequency of nuclear missegregation. Microtubule attachment at the bud neck was followed by shrinkage and a pulling action on the spindle. Enhancement of microtubule shrinkage at the bud neck required the Par-1-related, septin-dependent kinases (SDK) Hsl1 and Gin4. Neither the formin Bnr1 nor the actomyosin contractile ring was required for either microtubule capture or microtubule shrinkage. Together, our results indicate that septins and septin-dependent kinases may coordinate microtubule and actin functions in cell division.
Kusch
Justine
J
Institute of Biochemistry, Federal Institute of Technology, CH-8092 Zürich, Switzerland.
Meyer
Anne
A
Snyder
Michael P
MP
Barral
Yves
Y
D000205:Actomyosin / Q000502:physiology; D002467:Cell Nucleus; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D008941:Spindle Apparatus
D005656:Fungal Proteins; C110443:KAR9 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D000205:Actomyosin