title: Inhibition of SH2 domain/phosphoprotein association by a nonhydrolyzable phosphonopeptide.
abstract: Using the association between the pp60c-src/polyoma virus middle T antigen (mT) complex and phosphatidylinositol 3'-kinase (PI 3-kinase) as a prototype for phosphoprotein-SH2 domain interactions, we tested whether a nonhydrolyzable phosphonopeptide would inhibit association. (Phosphonomethyl)-phenylalanine (Pmp) is a nonnatural analogue of phosphotyrosine in which the > C-O-PO3H2 moiety is replaced by > C-CH2-PO3H2. We synthesized a 13 amino acid phosphonopeptide (mT-Pmp315), a related phosphopeptide (mT-pY315), and an unmodified sequence (mT-Y315), all corresponding to the pp60c-src-phosphorylated site of the mT which is within a YMXM motif common to proteins that bind to and activate PI 3-kinase. Only the phosphonopeptide persistently blocked the in vitro association of the baculovirus-expressed pp60c-src/mT complex with cytosolic PI 3-kinase activity. Sustained inhibition of association by the phosphopeptide required the additional presence of vanadate, a potent protein tyrosine phosphatase (PTPase) inhibitor. The phosphopeptide and L-phosphonopeptide bound tightly (KD approximately 10-20 nM) and specifically to isolated SH2 domains of PI 3-kinase p85, demonstrating that the mechanism of inhibited association is competitive binding to PI 3-kinase SH2 domains. We conclude that the appropriate phosphonopeptide sequence inhibits the interaction between a tyrosine-phosphorylated protein and a cognate SH2 domain-containing protein and is resistant to the actions of PTPases. Proteolytically stable phosphonopeptide derivatives should be useful inhibitors of protein-protein interactions when introduced into cells and may provide a basis for the rational design of a new class of chemotherapeutic agent.
authors.affiliation: Joslin Diabetes Center, Brigham and Women's Hospital, Boston, Massachusetts 02215.
authors.forename: S M
authors.initials: SM
authors.lastname: Domchek
authors.forename: K R
authors.initials: KR
authors.lastname: Auger
authors.forename: S
authors.initials: S
authors.lastname: Chatterjee
authors.forename: T R
authors.initials: TR
authors.lastname: Burke
authors.forename: S E
authors.initials: SE
authors.lastname: Shoelson
mesh_terms: D000595:Amino Acid Sequence; D000952:Antigens, Polyomavirus Transforming / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D007163:Immunosorbent Techniques; D008969:Molecular Sequence Data; D063065:Organophosphonates / Q000737:chemistry / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D010748:Phosphopeptides / Q000737:chemistry / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D010770:Phosphotransferases / Q000737:chemistry / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D000952:Antigens, Polyomavirus Transforming; D063065:Organophosphonates; D010446:Peptide Fragments; D010710:Phosphates; D010748:Phosphopeptides; D010750:Phosphoproteins; D010770:Phosphotransferases; D019869:Phosphatidylinositol 3-Kinases; D016392:Proto-Oncogene Proteins pp60(c-src)