title: Crystallographic analysis of a full-length streptavidin with its C-terminal polypeptide bound in the biotin binding site.
abstract: The structure of a full-length streptavidin has been determined at 1.7 A resolution and shows that the 20 residue extension at the C terminus forms a well-ordered polypeptide loop on the surface of the tetramer. Residues 150-153 of the extension are bound to the ligand-binding site, possibly competing with exogenous ligands. The binding mode of these residues is compared with that of biotin and peptidic ligands. The observed structure helps to rationalize the observations that full-length mature streptavidin binds biotinylated macromolecules with reduced affinity.
authors.affiliation: Departments of Biological Structure and Biochemistry and the Biomolecular Structure Center, University of Washington, Box 357420, Seattle, WA 98195-7420, USA.
authors.forename: Isolde
authors.initials: I
authors.lastname: Le Trong
authors.forename: Nicolas
authors.initials: N
authors.lastname: Humbert
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Ward
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Stenkamp
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D001710:Biotin / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D019809:Streptavidin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013302:Streptomyces / Q000737:chemistry / Q000235:genetics; D014867:Water / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D014867:Water; D001710:Biotin; D019809:Streptavidin