Suppressors of ipl1-2 in Components of a Glc7 Phosphatase Complex, Cdc48 AAA ATPase, TORC1, and the Kinetochore

• Published in: G3 : genes - genomes - genetics 2012-12, Vol.2 (12), p.1687-1701
• Main Authors: Robinson, Lucy C, Phillips, Joshua, Brou, Lina, Boswell, Evan P, Tatchell, Kelly
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - metabolism; Amino Acid Sequence; Aurora Kinases; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; G2 Phase Cell Cycle Checkpoints; GTPase-Activating Proteins - genetics; GTPase-Activating Proteins - metabolism; Humans; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Investigations; Kinetochores - metabolism; M Phase Cell Cycle Checkpoints; Molecular Sequence Data; Mutation; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Phosphorylation; Protein Phosphatase 1 - genetics; Protein Phosphatase 1 - metabolism; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Sequence Alignment; Transcription Factors - genetics; Transcription Factors - metabolism; Valosin Containing Protein
• ISSN: 2160-1836; 2160-1836
• DOI: 10.1534/g3.112.003814

Abstract Ipl1/Aurora B is the catalytic subunit of a protein kinase complex required for chromosome segregation and nuclear division. Before anaphase, Ipl1 is required to establish proper kinetochore-microtubule associations and to regulate the spindle assembly checkpoint (SAC). The phosphatase Glc7/PP1 opposes Ipl1 for these activities. To investigate Ipl1 and Glc7 regulation in more detail, we isolated and characterized mutations in the yeast Saccharomyces cerevisiae that raise the restrictive temperature of the ipl-2 mutant. These suppressors include three intragenic, second-site revertants in IPL1; 17 mutations in Glc7 phosphatase components (GLC7, SDS22, YPI1); two mutations in SHP1, encoding a regulator of the AAA ATPase Cdc48; and a mutation in TCO89, encoding a subunit of the TOR Complex 1. Two revertants contain missense mutations in microtubule binding components of the kinetochore. rev76 contains the missense mutation duo1-S115F, which alters an essential component of the DAM1/DASH complex. The mutant is cold sensitive and arrests in G2/M due to activation of the SAC. rev8 contains the missense mutation ndc80-K204E. K204 of Ndc80 corresponds to K166 of human Ndc80 and the human Ndc80 K166E variant was previously shown to be defective for microtubule binding in vitro. In a wild-type IPL1 background, ndc80-K204E cells grow slowly and the SAC is activated. The slow growth and cell cycle delay of ndc80-K204E cells are partially alleviated by the ipl1-2 mutation. These data provide biological confirmation of a biochemically based model for the effect of phosphorylation on Ndc80 function.