title: Simultaneous binding of two peptidyl ligands by a SRC homology 2 domain.
abstract: Src homology 2 (SH2) domains mediate protein-protein interactions by recognizing phosphotyrosine (pY)-containing sequences of target proteins. In all of the SH2 domain-pY peptide interactions described to date, the SH2 domain binds to a single pY peptide. Here, determination of the cocrystal structure of the N-terminal SH2 domain of phosphatase SHP-2 bound to a class IV peptide (VIpYFVP) revealed a noncanonical 1:2 (protein-peptide) complex. The first peptide binds in a canonical manner with its pY side chain inserted in the usual binding pocket, while the second pairs up with the first to form two antiparallel β-strands that extend the central β-sheet of the SH2 domain. This unprecedented binding mode was confirmed in the solution phase by NMR experiments and shown to be adopted by pY peptides derived from cellular proteins. Site-directed mutagenesis and surface plasmon resonance studies revealed that the binding of the first peptide is pY-dependent, but phosphorylation is not required for the second peptide. Our findings suggest a potential new function for the SH2 domain as a molecular clamp to promote dimerization of signaling proteins.
authors.affiliation: Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jinjin
authors.initials: J
authors.lastname: Zhang
authors.forename: Chunhua
authors.initials: C
authors.lastname: Yuan
authors.forename: Ryan L
authors.initials: RL
authors.lastname: Hard
authors.forename: In-Hee
authors.initials: IH
authors.lastname: Park
authors.forename: Chenglong
authors.initials: C
authors.lastname: Li
authors.forename: Charles
authors.initials: C
authors.lastname: Bell
authors.forename: Dehua
authors.initials: D
authors.lastname: Pei
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000235:genetics; D019000:Phosphotyrosine / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D020349:Surface Plasmon Resonance; D018909:src Homology Domains / Q000235:genetics / Q000502:physiology*
chemical_list: D008024:Ligands; D010446:Peptide Fragments; D019000:Phosphotyrosine