title: Hyaluronan synthases: a decade-plus of novel glycosyltransferases.
abstract: Hyaluronan synthases (HASs) are glycosyltransferases that catalyze polymerization of hyaluronan found in vertebrates and certain microbes. HASs transfer two distinct monosaccharides in different linkages and, in certain cases, participate in polymer transfer out of the cell. In contrast, the vast majority of glycosyltransferases form only one sugar linkage. Although our understanding of HAS biochemistry is still incomplete, very good progress has been made since the first genetic identification of a HAS in 1993. New enzymes have been discovered, and some molecular details have emerged. Important findings are the lipid dependence of Class I HASs, the function of HASs as protein monomers, and the elucidation of mechanisms of synthesis by Class II HAS. We propose three classes of HASs based on differences in protein sequences, predicted membrane topologies, potential architectures, mechanisms, and direction of polymerization.
authors.affiliation: Department of Biochemistry and Molecular Biology and the Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA. paul-weigel@ouhsc.edu
authors.forename: Paul H
authors.initials: PH
authors.lastname: Weigel
authors.forename: Paul L
authors.initials: PL
authors.lastname: DeAngelis
mesh_terms: D000818:Animals; D002236:Carbohydrate Conformation; D002462:Cell Membrane / Q000201:enzymology; D014453:Glucuronosyltransferase / Q000145:classification* / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000096:biosynthesis*; D008563:Membrane Lipids / Q000378:metabolism
chemical_list: D008563:Membrane Lipids; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; D000076002:Hyaluronan Synthases