title: The EBP50-moesin interaction involves a binding site regulated by direct masking on the FERM domain.
abstract: Members of the ezrin-radixin-moesin (ERM) protein family serve as regulated microfilament-membrane crosslinking proteins that, upon activation, bind the scaffolding protein ERM-phosphoprotein of 50 kDa (EBP50). Here we report a 3.5 A resolution diffraction analysis of a complex between the active moesin N-terminal FERM domain and a 38 residue peptide from the C terminus of EBP50. This crystallographic result, combined with sequence and structural comparisons, suggests that the C-terminal 11 residues of EBP50 binds as an alpha-helix at the same site occupied in the dormant monomer by the last 11 residues of the inhibitory moesin C-terminal tail. Biochemical support for this interpretation derives from in vitro studies showing that appropriate mutations in both the EBP50 tail peptide and the FERM domain reduce binding, and that a peptide representing just the C-terminal 14 residues of EBP50 also binds to moesin. Combined with the recent identification of the I-CAM-2 binding site on the ERM FERM domain (Hamada, K., Shimizu, T., Yonemura, S., Tsukita, S., and Hakoshima, T. (2003) EMBO J. 22, 502-514), this study reveals that the FERM domain contains two distinct binding sites for membrane-associated proteins. The contribution of each ligand to ERM function can now be dissected by making structure-based mutations that specifically affect the binding of each ligand.
authors.affiliation: Department of Molecular Biology and Genetics, Biotechnology Building, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Casey M
authors.initials: CM
authors.lastname: Finnerty
authors.forename: David
authors.initials: D
authors.lastname: Chambers
authors.forename: Janet
authors.initials: J
authors.lastname: Ingraffea
authors.forename: H Richard
authors.initials: HR
authors.lastname: Faber
authors.forename: P Andrew
authors.initials: PA
authors.lastname: Karplus
authors.forename: Anthony
authors.initials: A
authors.lastname: Bretscher
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003598:Cytoskeletal Proteins; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D000099149:Ezrin
chemical_list: D003598:Cytoskeletal Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D000099149:Ezrin; C071058:moesin