The specificity of the N-terminal SH2 domain of SHP-2 is modified by a single point mutation.
SH2 domains are small protein domains of approximately 100 amino acids that bind to phosphotyrosine (pY) in the context of a specific sequence surrounding the target pY. In general, the residues C-terminal to the pY of the binding target are considered most important for defining the binding specificity, and in particular the pY + 1 and pY + 3 residues (i.e., the first and third amino acids C-terminal to the pY). However, our previous studies with the SH2 domains of the protein tyrosine phosphatase SHP-2 [Huyer, G., Li, Z. M., Adam, M., Huckle, W. R., and Ramachandran, C. (1995) Biochemistry 34, 1040-1049] indicated important interactions with the pY - 2 residue as well. In the SH2 domains of SHP-2, the highly conserved alphaA2 Arg is replaced by Gly. A comparison of the published crystal structures of the Src SH2 domain and the N-terminal SH2 domain of SHP-2 complexed with high-affinity peptides suggested that the alphaA2 Gly of SHP-2 creates a gap which is filled by the side chain of the pY - 2 residue of the bound peptide. It was predicted that replacing this Gly with Arg would alter or eliminate the involvement of the pY - 2 residue in binding. The alphaA2 Gly --> Arg mutant was constructed, and indeed, this mutant no longer required residues N-terminal to the target pY for high-affinity binding, making its specificity more like that of other SH2 domains. The alphaA2 Gly is clearly involved in directing the unusual requirement for the pY - 2 residue in the binding sequence of this SH2 domain, which has important implications for its in vivo targeting and specificity.
Huyer
G
G
Department of Biochemistry and Molecular Biology, Merck Frosst Centre for Therapeutic Research, P.O. Box 1005, Pointe-Claire-Dorval, Quebec H9R 4P8, Canada.
Ramachandran
C
C
D000595:Amino Acid Sequence; D001665:Binding Sites; D015374:Biosensing Techniques; D003001:Cloning, Molecular; D047908:Intracellular Signaling Peptides and Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics*; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D016415:Sequence Alignment; D018909:src Homology Domains
D047908:Intracellular Signaling Peptides and Proteins; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases