title: Competitive interactions of collagen and a jararhagin-derived disintegrin peptide with the integrin alpha2-I domain.
abstract: Integrin alpha2beta1 is a major receptor required for activation and adhesion of platelets, through the specific recognition of collagen by the alpha2-I domain (alpha2-I), which binds fibrillar collagen via Mg(2+)-bridged interactions. The crystal structure of a truncated form of the alpha2-I domain, bound to a triple helical collagen peptide, revealed conformational changes suggestive of a mechanism where the ligand-bound I domain can initiate and propagate conformational change to the full integrin complex. Collagen binding by alpha2-I and fibrinogen-dependent platelet activity can be inhibited by snake venom polypeptides. Here we describe the inhibitory effect of a short cyclic peptide derived from the snake toxin metalloprotease jararhagin, with specific amino acid sequence RKKH, on the ability of alpha2-I to bind triple helical collagen. Isothermal titration calorimetry measurements showed that the interactions of alpha2-I with collagen or RKKH peptide have similar affinities, and NMR chemical shift mapping experiments with (15)N-labeled alpha2-I, and unlabeled RKKH peptide, indicate that the peptide competes for the collagen-binding site of alpha2-I but does not induce a large scale conformational rearrangement of the I domain.
authors.affiliation: Burnham Institute for Medical Research, La Jolla, California 92037, USA.
authors.forename: Lester J
authors.initials: LJ
authors.lastname: Lambert
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Bobkov
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Smith
authors.forename: Francesca M
authors.initials: FM
authors.lastname: Marassi
mesh_terms: D000595:Amino Acid Sequence; D003094:Collagen / Q000737:chemistry*; D003435:Crotalid Venoms / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005340:Fibrinogen / Q000737:chemistry; D006801:Humans; D016023:Integrins / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008666:Metalloendopeptidases / Q000737:chemistry*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D000097146:Bothrops jararaca Venom
chemical_list: D003094:Collagen; D003435:Crotalid Venoms; D005340:Fibrinogen; D016023:Integrins; D008274:Magnesium; D008666:Metalloendopeptidases; D010455:Peptides; D000097146:Bothrops jararaca Venom