Structure-Function Relationship of the Bik1-Bim1 Complex.

In budding yeast, the microtubule plus-end tracking proteins Bik1 (CLIP-170) and Bim1 (EB1) form a complex that interacts with partners involved in spindle positioning, including Stu2 and Kar9. Here, we show that the CAP-Gly and coiled-coil domains of Bik1 interact with the C-terminal ETF peptide of Bim1 and the C-terminal ...
tail region of Stu2, respectively. The crystal structures of the CAP-Gly domain of Bik1 (Bik1CG) alone and in complex with an ETF peptide revealed unique, functionally relevant CAP-Gly elements, establishing Bik1CG as a specific C-terminal phenylalanine recognition domain. Unlike the mammalian CLIP-170-EB1 complex, Bik1-Bim1 forms ternary complexes with the EB1-binding motifs SxIP and LxxPTPh, which are present in diverse proteins, including Kar9. Perturbation of the Bik1-Bim1 interaction in vivo affected Bik1 localization and astral microtubule length. Our results provide insight into the role of the Bik1-Bim1 interaction for cell division, and demonstrate that the CLIP-170-EB1 module is evolutionarily flexible.
Mesh Terms:
Amino Acid Sequence, Binding Sites, Cell Cycle Proteins, Cell Division, Cloning, Molecular, Crystallography, X-Ray, Escherichia coli, Evolution, Molecular, Gene Expression, Genetic Vectors, Microtubule Proteins, Microtubule-Associated Proteins, Microtubules, Models, Molecular, Nuclear Proteins, Protein Binding, Protein Conformation, alpha-Helical, Protein Conformation, beta-Strand, Protein Interaction Domains and Motifs, Recombinant Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Alignment, Sequence Homology, Amino Acid, Spindle Apparatus, Structure-Activity Relationship
Date: Dec. 03, 2017
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