Crystal Structure of an alpha-1,4-N-acetylhexosaminyltransferase (EXTL2), a member of the exostosin gene family involved in heparan sulfate biosynthesisPedersen, L.C., Dong, J., Taniguchi, F., Kitagawa, H., Krahn, J.M., Pedersen, L.G., Sugahara, K., Negishi, M.
(2003) J.Biol.Chem. 278: 14420-14428
- PubMed: 12562774
- DOI: 10.1074/jbc.M210532200
- Primary Citation of Related Structures:  1OMX, 1OMZ, 1ON8
- PubMed Abstract:
EXTL2, an alpha1,4-N-acetylhexosaminyltransferase, catalyzes the transfer reaction of N-acetylglucosamine and N-acetylgalactosamine from the respective UDP-sugars to the non-reducing end of [glucuronic acid]beta1-3[galactose]beta1-O-naphthalenemethan ...
EXTL2, an alpha1,4-N-acetylhexosaminyltransferase, catalyzes the transfer reaction of N-acetylglucosamine and N-acetylgalactosamine from the respective UDP-sugars to the non-reducing end of [glucuronic acid]beta1-3[galactose]beta1-O-naphthalenemethanol, an acceptor substrate analog of the natural common linker of various glycosylaminoglycans. We have solved the x-ray crystal structure of the catalytic domain of mouse EXTL2 in the apo-form and with donor substrates UDP-N-acetylglucosamine and UDP-N-acetylgalactosamine. In addition, a structure of the ternary complex with UDP and the acceptor substrate analog [glucuronic acid]beta1-3[galactose]beta1-O-naphthalenemethanol has been determined. These structures reveal three highly conserved residues, Asn-243, Asp-246, and Arg-293, located at the active site. Mutation of these residues greatly decreases the activity. In the ternary complex, an interaction exists between the beta-phosphate of the UDP leaving group and the acceptor hydroxyl of the substrate that may play a functional role in catalysis. These structures represent the first structures from the exostosin gene family and provide important insight into the mechanisms of alpha1,4-N-acetylhexosaminyl transfer in heparan biosynthesis.
Pharmacogenetics Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institute of Health, Research Triangle Park, North Carolina 27709, USA.