4bl0
From Proteopedia
Crystal structure of yeast Bub3-Bub1 bound to phospho-Spc105
Structural highlights
Function[BUB3_YEAST] Required for cell cycle arrest in response to loss of microtubule function. Component of the spindle assembly checkpoint which is a feedback control that prevents cells with incompletely assembled spindles from leaving mitosis. Component of the mitotic checkpoint complex (MCC) which inhibits the ubiquitin ligase activity of the anaphase promoting complex/cyclosome (APC/C) by preventing its activation by CDC20. The formation of a MAD1-BUB1-BUB3 complex seems to be required for the spindle checkpoint mechanism.[1] [SP105_YEAST] Forms a kinetochore complex with SPC105 which is required for kinetochore binding by a discrete subset of kMAPs (BIM1, BIK1 and SLK19) and motors (CIN8, KAR3). Involved in kinetochore-microtubule binding and the spindle assembly checkpoint.[2] [BUB1_YEAST] Involved in cell cycle checkpoint enforcement. The formation of a MAD1-BUB1-BUB3 complex seems to be required for the spindle checkpoint mechanism. Catalyzes the phosphorylation of BUB3 and its autophosphorylation. Associates with centromere (CEN) DNA via interaction with SKP1. The association with SKP1 is required for the mitotic delay induced by kinetochore tension defects, but not for the arrest induced by spindle depolymerization or kinetochore assembly defects.[3] Publication Abstract from PubMedRegulation of macromolecular interactions by phosphorylation is crucial in signaling networks. In the spindle assembly checkpoint (SAC), which enables errorless chromosome segregation, phosphorylation promotes recruitment of SAC proteins to tensionless kinetochores. The SAC kinase Mps1 phosphorylates multiple Met-Glu-Leu-Thr (MELT) motifs on the kinetochore subunit Spc105/Knl1. The phosphorylated MELT motifs (MELT(P)) then promote recruitment of downstream signaling components. How MELT(P) motifs are recognized is unclear. In this study, we report that Bub3, a 7-bladed beta-propeller, is the MELT(P) reader. It contains an exceptionally well-conserved interface that docks the MELT(P) sequence on the side of the beta-propeller in a previously unknown binding mode. Mutations targeting the Bub3 interface prevent kinetochore recruitment of the SAC kinase Bub1. Crucially, they also cause a checkpoint defect, showing that recognition of phosphorylated targets by Bub3 is required for checkpoint signaling. Our data provide the first detailed mechanistic insight into how phosphorylation promotes recruitment of checkpoint proteins to kinetochores. DOI:http://dx.doi.org/10.7554/eLife.01030.001. Bub3 reads phosphorylated MELT repeats to promote spindle assembly checkpoint signaling.,Primorac I, Weir JR, Chiroli E, Gross F, Hoffmann I, van Gerwen S, Ciliberto A, Musacchio A Elife. 2013 Sep 24;2:e01030. doi: 10.7554/eLife.01030. PMID:24066227[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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Categories: Atcc 18824 | Large Structures | Non-specific serine/threonine protein kinase | Musacchio, A | Primorac, I | Weir, J R | Aneuploidy | Blinkin | Bubr1 | Casc5 | Cell cycle | Cell division | Gle2 | Gleb | Kinetochore | Knl1 | Mad1 | Mad2 | Mad3 | Mitosis | Rae1 | Spc7 | Spindle assembly checkpoint
