title: Structure of the SH3 domain of human osteoclast-stimulating factor at atomic resolution.
abstract: Osteoclast-stimulating factor (OSF) is an intracellular signaling protein, produced by osteoclasts themselves, that enhances osteoclast formation and bone resorption. It is thought to act via an Src-related signaling pathway and contains SH3 and ankyrin-repeat domains which are involved in protein-protein interactions. As part of a structure-based anti-bone-loss drug-design program, the atomic resolution X-ray structure of the recombinant human OSF SH3 domain (hOSF-SH3) has been determined. The domain, residues 12-72, yielded crystals that diffracted to the ultrahigh resolution of 1.07 A. The overall structure shows a characteristic SH3 fold consisting of two perpendicular beta-sheets that form a beta-barrel. Structure-based sequence alignment reveals that the putative proline-rich peptide-binding site of hOSF-SH3 consists of (i) residues that are highly conserved in the SH3-domain family, including residues Tyr21, Phe23, Trp49, Pro62, Asn64 and Tyr65, and (ii) residues that are less conserved and/or even specific to hOSF, including Thr22, Arg26, Thr27, Glu30, Asp46, Thr47, Asn48 and Leu60, which might be key to designing specific inhibitors for hOSF to fight osteoporosis and related bone-loss diseases. There are a total of 13 well defined water molecules forming hydrogen bonds with the above residues in and around the peptide-binding pocket. Some of those water molecules might be important for drug-design approaches. The hOSF-SH3 structure at atomic resolution provides an accurate framework for structure-based design of its inhibitors.
authors.affiliation: Laboratory for Structural Biology, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA. chenlq@uah.edu
authors.forename: Liqing
authors.initials: L
authors.lastname: Chen
authors.forename: Yujun
authors.initials: Y
authors.lastname: Wang
authors.forename: David
authors.initials: D
authors.lastname: Wells
authors.forename: Diana
authors.initials: D
authors.lastname: Toh
authors.forename: Hunt
authors.initials: H
authors.lastname: Harold
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Enrico
authors.initials: E
authors.lastname: DiGiammarino
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Meehan
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D015195:Drug Design; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D010010:Osteoclasts / Q000378:metabolism*; D010455:Peptides / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D013329:Structure-Activity Relationship; D018909:src Homology Domains / Q000235:genetics
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D010455:Peptides; D011994:Recombinant Proteins; C408994:osteoclast stimulating factor