1i5k
From Proteopedia
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STRUCTURE AND BINDING DETERMINANTS OF THE RECOMBINANT KRINGLE-2 DOMAIN OF HUMAN PLASMINOGEN TO AN INTERNAL PEPTIDE FROM A GROUP A STREPTOCOCCAL SURFACE PROTEIN
Contents |
Overview
The X-ray crystal structure of a complex of a modified recombinant, kringle-2 domain of human plasminogen, K2Pg[C4G/E56D/L72Y] (mK2Pg), containing an upregulated lysine-binding site, bound to a functional 30, residue internal peptide (VEK-30) from an M-type protein of a group A, Streptococcus surface protein, has been determined by molecular, replacement methods using K4Pg as a model, and refined at 2.7 A resolution, to a R-factor of 19.5 %. The X-ray crystal structure shows that VEK-30, exists as a nearly end-to-end alpha-helix in the complex with mK2Pg. The, final structure also revealed that Arg17 and His18 of VEK-30 served as, cationic loci for Asp54 and Asp56 of the consensus lysine-binding site of, mK2Pg, while Glu20 of VEK-30 coordinates with Arg69 of the cationic, binding site of mK2Pg. The hydrophobic ligand-binding pocket in mK2Pg, consisting primarily of Trp60 and Trp70, situated between the positive and, negative centers of the lysine-binding site, is utilized in a novel manner, in stabilizing the interaction with VEK-30 by forming a, cation-pi-electron-mediated association with the positive side-chain of, Arg17 of this peptide. Additional lysine-binding sites, as well as exosite, electrostatic and hydrogen bonding interactions involving Glu9 and Lys14, of VEK-30, were observed in the structural model. The importance of these, interactions were tested in solution by investigating the binding, constants of synthetic variants of VEK-30 to mK2Pg, and it was found that, Lys14, Arg17, His18, and Glu20 of VEK-30 were the most critical amino acid, binding determinants. With regard to the solution studies, circular, dichroism analysis of the titration of VEK-30 with mK2Pg demonstrated that, the peptidic alpha-helical structure increased substantially when bound to, the kringle module, in agreement with the X-ray results.This investigation, is the first to delineate structurally the mode of interaction of the, lysine-binding site of a kringle with an internal pseudo-lysine residue of, a peptide or protein that functionally interacts with a kringle module, and serves as a paradigm for this important class of interactions.
Disease
Known diseases associated with this structure: Conjunctivitis, ligneous OMIM:[173350], Plasminogen Tochigi disease OMIM:[173350], Plasminogen deficiency, types I and II OMIM:[173350], Thrombophilia, dysplasminogenemic OMIM:[173350]
About this Structure
1I5K is a Protein complex structure of sequences from Homo sapiens. Active as Plasmin, with EC number 3.4.21.7 Full crystallographic information is available from OCA.
Reference
Structure and binding determinants of the recombinant kringle-2 domain of human plasminogen to an internal peptide from a group A Streptococcal surface protein., Rios-Steiner JL, Schenone M, Mochalkin I, Tulinsky A, Castellino FJ, J Mol Biol. 2001 May 11;308(4):705-19. PMID:11350170
Page seeded by OCA on Mon Nov 12 17:26:36 2007
