title: The crystal structure of the N-terminal SH3 domain of Grb2.
abstract: The 3-D structure of the N-terminal SH3 domain of the regulatory protein Grb2 has been determined by X-ray analysis at 2.8 A resolution and refined to a crystallographic R factor of 21.5%. The structure, which is very similar to those of other SH3 domains, consists of two orthogonal, antiparallel up-down beta-sheets, with three variable loops and a 3(10) helix. Docking of the proline-rich peptide, 3BP1 on Grb2-N SH3, shows that the polyproline type II helix can bind the SH3 domain forming conserved hydrogen bonds between the main-chain carbonyl oxygens of Met4 and Pro7 of the proline-rich peptide and the reoriented side-chains of Trp36 and Asn51, respectively, and a hydrogen bond between the main-chain carbonyl of Leu8 of the proline rich peptide with the side-chain OH of Tyr52 of the Grb2-N SH3. The peptide side-chain binding occurs on the surface of SH3 domain at three major sites involving the side-chains of the residues in the hydrophobic patch (Tyr7, Phe9, Trp36, Phe47, Pro49 and Tyr52) and the RT-Src and n-Src loops of the SH3 domain. The proline-rich peptides could bind the Grb2-N SH3 in either orientation and maintain the key hydrogen bonds because of the pseudo-symmetry of the polyproline type II helix. However, for the mSos1 peptide a salt bridge can be formed between the arginine of the proline-rich peptide and the protein at Asp15, Glu16 and Glu31 only in one direction; this orientation seems to be strongly preferred. The conservatively varied RGD sequence motif (sometimes KGE or KGD) in SH3 domains might be involved in interactions at the cell membrane.
authors.affiliation: Department of Crystallography, Birkbeck College, University of London, U.K.
authors.forename: L
authors.initials: L
authors.lastname: Guruprasad
authors.forename: V
authors.initials: V
authors.lastname: Dhanaraj
authors.forename: D
authors.initials: D
authors.lastname: Timm
authors.forename: T L
authors.initials: TL
authors.lastname: Blundell
authors.forename: I
authors.initials: I
authors.lastname: Gout
authors.forename: M D
authors.initials: MD
authors.lastname: Waterfield
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D051380:GRB2 Adaptor Protein; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; D010455:Peptides; D011506:Proteins; D011993:Recombinant Fusion Proteins