title: Structural determinants for EB1-mediated recruitment of APC and spectraplakins to the microtubule plus end.
abstract: EB1 is a member of a conserved protein family that localizes to growing microtubule plus ends. EB1 proteins also recruit cell polarity and signaling molecules to microtubule tips. However, the mechanism by which EB1 recognizes cargo is unknown. Here, we have defined a repeat sequence in adenomatous polyposis coli (APC) that binds to EB1's COOH-terminal domain and identified a similar sequence in members of the microtubule actin cross-linking factor (MACF) family of spectraplakins. We show that MACFs directly bind EB1 and exhibit EB1-dependent plus end tracking in vivo. To understand how EB1 recognizes APC and MACFs, we solved the crystal structure of the EB1 COOH-terminal domain. The structure reveals a novel homodimeric fold comprised of a coiled coil and four-helix bundle motif. Mutational analysis reveals that the cargo binding site for MACFs maps to a cluster of conserved residues at the junction between the coiled coil and four-helix bundle. These results provide a structural understanding of how EB1 binds two regulators of microtubule-based cell polarity.
authors.affiliation: The Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94107, USA.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Slep
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Rogers
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Elliott
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohkura
authors.forename: Peter A
authors.initials: PA
authors.lastname: Kolodziej
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Vale
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002478:Cells, Cultured; D004330:Drosophila; D008840:Microfilament Proteins / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000235:genetics; D011485:Protein Binding
chemical_list: D025601:Adenomatous Polyposis Coli Protein; C405804:EB1 microtubule binding proteins; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins