title: A Bub1-Mad1 interaction targets the Mad1-Mad2 complex to unattached kinetochores to initiate the spindle checkpoint.
abstract: Recruitment of Mad1-Mad2 complexes to unattached kinetochores is a central event in spindle checkpoint signaling. Despite its importance, the mechanism that recruits Mad1-Mad2 to kinetochores is unclear. In this paper, we show that MAD-1 interacts with BUB-1 in Caenorhabditis elegans. Mutagenesis identified specific residues in a segment of the MAD-1 coiled coil that mediate the BUB-1 interaction. In addition to unattached kinetochores, MAD-1 localized between separating meiotic chromosomes and to the nuclear periphery. Mutations in the MAD-1 coiled coil that selectively disrupt interaction with BUB-1 eliminated MAD-1 localization to unattached kinetochores and between meiotic chromosomes, both of which require BUB-1, and abrogated checkpoint signaling. The identified MAD-1 coiled-coil segment interacted with a C-terminal region of BUB-1 that contains its kinase domain, and mutations in this region prevented MAD-1 kinetochore targeting independently of kinase activity. These results delineate an interaction between BUB-1 and MAD-1 that targets MAD-1-MAD-2 complexes to kinetochores and is essential for spindle checkpoint signaling.
authors.affiliation: Ludwig Institute for Cancer Research and 2 Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92037.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Moyle
authors.forename: Taekyung
authors.initials: T
authors.lastname: Kim
authors.forename: Neil
authors.initials: N
authors.lastname: Hattersley
authors.forename: Julien
authors.initials: J
authors.lastname: Espeut
authors.forename: Dhanya K
authors.initials: DK
authors.lastname: Cheerambathur
authors.forename: Karen
authors.initials: K
authors.lastname: Oegema
authors.forename: Arshad
authors.initials: A
authors.lastname: Desai
mesh_terms: D000705:Anaphase / Q000502:physiology; D000818:Animals; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002875:Chromosomes / Q000378:metabolism; D018386:Kinetochores / Q000378:metabolism* / Q000502:physiology; D059566:M Phase Cell Cycle Checkpoints; D064246:Mad2 Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D008540:Meiosis / Q000502:physiology; D008954:Models, Biological; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques
chemical_list: D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; C412839:MDF-1 protein, C elegans; D064246:Mad2 Proteins; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; C588208:bub-1 protein, C elegans