Mps1 kinase promotes sister-kinetochore bi-orientation by a tension-dependent mechanism.
Segregation of sister chromatids to opposite spindle poles during anaphase is dependent on the prior capture of sister kinetochores by microtubules extending from opposite spindle poles (bi-orientation). If sister kinetochores attach to microtubules from the same pole (syntelic attachment), the kinetochore-spindle pole connections must be re-oriented to be converted to proper bi-orientation. This re-orientation is facilitated by Aurora B kinase (Ipl1 in budding yeast), which eliminates kinetochore-spindle pole connections that do not generate tension. Mps1 is another evolutionarily conserved protein kinase, required for spindle-assembly checkpoint and, in some organisms, for duplication of microtubule-organizing centers. Separately from these functions, however, Mps1 has an important role in chromosome segregation. Here we show that, in budding yeast, Mps1 has a crucial role in establishing sister-kinetochore bi-orientation on the mitotic spindle. Failure in bi-orientation with inactive Mps1 is not due to a lack of kinetochore-spindle pole connections by microtubules, but due to a defect in properly orienting the connections. Mps1 promotes re-orientation of kinetochore-spindle pole connections and eliminates those that do not generate tension between sister kinetochores. We did not find evidence that Ipl1 regulates Mps1 or vice versa; therefore, they play similar, but possibly independent, roles in facilitating bi-orientation.
Wellcome Trust Centre for Gene Regulation & Expression, College of Life Sciences, University of Dundee, MSI/WTB/JBC Complex, Dundee DD1 5EH, UK.
Jean-François
JF
Maure
Etsushi
E
Kitamura
Tomoyuki U
TU
Tanaka
D064127:Aurora Kinases; D047908:Intracellular Signaling Peptides and Proteins; D018386:Kinetochores / Q000378:metabolism*; D008677:Metaphase / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D004718:Saccharomycetales; D008941:Spindle Apparatus / Q000378:metabolism*
D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D064127:Aurora Kinases; C576961:IPL1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C093416:MPS1 protein, S cerevisiae