4a1g
The crystal structure of the human Bub1 TPR domain in complex with the KI motif of Knl1
Structural highlights
DiseaseKNL1_HUMAN Autosomal recessive primary microcephaly. A chromosomal aberration involving KNL1 is associated with acute myeloblastic leukemia (AML). Translocation t(11;15)(q23;q14) with KMT2A. May give rise to a KMT2A-KNL1 fusion protein.[1] The disease is caused by variants affecting the gene represented in this entry. FunctionKNL1_HUMAN Performs two crucial functions during mitosis: it is essential for spindle-assembly checkpoint signaling and for correct chromosome alignment. Required for attachment of the kinetochores to the spindle microtubules. Directly links BUB1 and BUB1B to kinetochores. Part of the MIS12 complex, which may be fundamental for kinetochore formation and proper chromosome segregation during mitosis. Acts in coordination with CENPK to recruit the NDC80 complex to the outer kinetochore.[2] [3] [4] Publication Abstract from PubMedThe function of the essential checkpoint kinases Bub1 and BubR1 requires their recruitment to mitotic kinetochores. Kinetochore recruitment of Bub1 and BubR1 is proposed to rely on the interaction of the tetratricopeptide repeats (TPRs) of Bub1 and BubR1 with two KI motifs in the outer kinetochore protein Knl1. We determined the crystal structure of the Bub1 TPRs in complex with the cognate Knl1 KI motif and compared it with the structure of the equivalent BubR1TPR-KI motif complex. The interaction developed along the convex surface of the TPR assembly. Point mutations on this surface impaired the interaction of Bub1 and BubR1 with Knl1 in vitro and in vivo but did not cause significant displacement of Bub1 and BubR1 from kinetochores. Conversely, a 62-residue segment of Bub1 that includes a binding domain for the checkpoint protein Bub3 and is C terminal to the TPRs was necessary and largely sufficient for kinetochore recruitment of Bub1. These results shed light on the determinants of kinetochore recruitment of Bub1. Structural analysis reveals features of the spindle checkpoint kinase Bub1-kinetochore subunit Knl1 interaction.,Krenn V, Wehenkel A, Li X, Santaguida S, Musacchio A J Cell Biol. 2012 Feb 20;196(4):451-67. Epub 2012 Feb 13. PMID:22331848[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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