title: Post-translational modifications regulate assembly of early spindle orientation complex in yeast.
abstract: Mitosis begins with the tethering of chromosomes to the mitotic spindle and their orientation perpendicular to the axis of cell division. In budding yeast, mitotic spindle orientation and the subsequent chromosome segregation are two independent processes. Early spindle orientation is driven by the actin-bound myosin Myo2p, which interacts with the adapter Kar9p. The latter also binds to microtubule-associated Bim1p, thereby connecting both types of cytoskeleton. This study focuses on the interaction between Kar9p and Bim1p and its regulation. We solved the crystal structure of the previously reported Kar9p-binding motif of Bim1p and identified a second, novel Kar9p interaction domain. We further show that two independent post-translational modification events regulate their interaction. Whereas Kar9p sumoylation is required for efficient complex formation with Bim1p, Aurora B/Ipl1p-dependent phosphorylation of Bim1p down-regulates their interaction. The observed effects of these modifications allow us to propose a novel regulatory framework for the assembly and disassembly of the early spindle orientation complex.
authors.affiliation: Institute of Structural Biology, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Hüls
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Storchova
authors.forename: Dierk
authors.initials: D
authors.lastname: Niessing
mesh_terms: D020816:Amino Acid Motifs; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D008868:Microtubule Proteins / Q000737:chemistry / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000378:metabolism; D024701:Myosin Type V / Q000737:chemistry / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D008941:Spindle Apparatus / Q000737:chemistry / Q000378:metabolism*; D058207:Sumoylation / Q000502:physiology
chemical_list: C119683:BIM1 protein, S cerevisiae; D018797:Cell Cycle Proteins; C110443:KAR9 protein, S cerevisiae; C077512:MYO2 protein, S cerevisiae; D008868:Microtubule Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D024701:Myosin Type V; D018995:Myosin Heavy Chains