Demonstration of a novel UDPGalNAc:GlcNAc beta 1-4 N-acetylgalactosaminyltransferase in extracts of Schistosoma mansoni.
It was recently demonstrated that complex-type N-linked oligosaccharides in glycoproteins synthesized by Schistosoma mansoni contain the unusual terminal sequence GalNAc beta 1-4GlcNAc beta 1-2Man alpha 1-2R. This structure suggests that the parasite might contain a novel glycosyltransferase that can add GalNAc to terminal GlcNAc residues in N-linked oligosaccharides. This report describes an assay for this enzyme, designated UDPGalNAc:GlcNAc beta 1-4 N-acetylgalactosaminyltransferase (beta 1-4GalNAcT), and demonstrates the presence of the enzyme activity in schistosome extracts. As an acceptor for the beta 1-4GalNAcT, we prepared from human fibrinogen a truncated biantennary glycopeptide that contained terminal GlcNAc residues. When this acceptor was incubated with schistosome extracts in the presence of UDP-[3H]GalNAc, Mn2+, and detergent, [3H]GalNAc was transferred to the glycopeptide acceptor. Approximately 75% of the radioactivity in the product isolated by lectin affinity chromatography was recovered as [3H]GalNAc following hydrolysis; likewise, a majority of the isolated product was bound by immobilized Wisteria floribunda agglutinin, a lectin that binds to schistosome-derived oligosaccharides containing terminal beta 1-4-linked GalNAc residues. The activity of the beta 1-4GalNAcT in schistosome extracts was dependent on time, protein, and UDPGalNAc.
Srivatsan
J
J
University of Oklahoma Health Sciences Center, Department of Biochemistry and Molecular Biology, Oklahoma City 73104.
Smith
D F
DF
Cummings
R D
RD
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002240:Carbohydrate Sequence; D002846:Chromatography, Affinity; D003208:Concanavalin A; D037102:Lectins; D008969:Molecular Sequence Data; D017350:N-Acetylgalactosaminyltransferases; D037121:Plant Lectins; D034781:Receptors, N-Acetylglucosamine; D012550:Schistosoma mansoni / Q000201:enzymology*
D037102:Lectins; D037121:Plant Lectins; D034781:Receptors, N-Acetylglucosamine; C040129:wisteria lectin; D003208:Concanavalin A; D000255:Adenosine Triphosphate; D017350:N-Acetylgalactosaminyltransferases; C023220:(N-acetylneuraminyl)-galactosylglucosylceramide N-acetylgalactosaminyltransferase