Structural analysis reveals features of the spindle checkpoint kinase Bub1-kinetochore subunit Knl1 interaction

Veronica Krenn, Annemarie Wehenkel, Xiaozheng Li, Stefano Santaguida, Andrea Musacchio

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Abstract

The 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.

Original languageEnglish
Pages (from-to)451-467
Number of pages17
JournalJournal of Cell Biology
Volume196
Issue number4
DOIs
Publication statusPublished - 2012

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ASJC Scopus subject areas

  • Cell Biology

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