title: Crystal structure of beta 1,3-glucuronyltransferase I in complex with active donor substrate UDP-GlcUA.
abstract: Beta1,3-glucuronyltransferase (GlcAT-I) is an essential enzyme involved in heparan sulfate and chondroitin sulfate biosynthesis. GlcAT-I is an inverting glycosyltransferase that catalyzes the transfer of glucuronic acid (GlcUA) to the common growing linker region Galbeta1-3Galbeta1-4Xyl that is attached to a serine side chain of a core protein. Previously the structure of GlcAT-I has been solved in the presence of the donor product UDP and an acceptor analog Galbeta1-3Galbeta1-4Xyl (Pedersen, L. C., Tsuchida, K., Kitagawa, H., Sugahara, K., Darden, T. A. & Negishi, M. (2000) J. Biol. Chem. 275, 34580-34585). Here we report the x-ray crystal structure of GlcAT-I in complex with the complete donor UDP-GlcUA, thereby providing structures of an inverting glycosyltransferase in which both the complete donor and acceptor substrates are present in the active site. This structure supports the in-line displacement reaction mechanism previously proposed. It also provides information on the essential amino acid residues that determine donor substrate specificity.
authors.affiliation: Laboratory of Reproductive and Developmental Toxicology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Lars C
authors.initials: LC
authors.lastname: Pedersen
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Darden
authors.forename: Masahiko
authors.initials: M
authors.lastname: Negishi
mesh_terms: D001120:Arginine / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D014453:Glucuronosyltransferase / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry; D006801:Humans; D008956:Models, Chemical; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D013379:Substrate Specificity; D013696:Temperature; D014535:Uridine Diphosphate Glucuronic Acid / Q000737:chemistry*
chemical_list: D011994:Recombinant Proteins; D014535:Uridine Diphosphate Glucuronic Acid; D001224:Aspartic Acid; D006639:Histidine; D001120:Arginine; C111364:galactosylgalactoylxylosylprotein 3-beta-glucuronosyltransferase; D014453:Glucuronosyltransferase