Characterization of anN-Acetylglucosamine-6-O-sulfotransferase from Human Respiratory Mucosa Active on Mucin Carbohydrate Chains

• Published in: The Journal of biological chemistry 1997-11, Vol.272 (47), p.29493-29501
• Main Authors: Degroote, Sophie, Lo-Guidice, Jean-Marc, Strecker, Gérard, Ducourouble, Marie-Paule, Roussel, Philippe, Lamblin, Geneviève
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.272.47.29493

A microsomal GlcNAc-6-O-sulfotransferase activity from human bronchial mucosa, able to transfer a sulfate group from adenosine 3′-phosphate 5′-phosphosulfate onto methyl-N-acetylglucosaminides or terminal N-acetylglucosamine residues of carbohydrate chains from human respiratory mucins, has been characterized. The reaction products containing a terminal HO3S-6GlcNAc were identified by high performance anion-exchange chromatography. Using methyl-β-N-acetylglucosaminide as a substrate, the optimal activity was obtained with 0.1% Triton X-100, 30 mm NaF, 20 mm Mn2+, 5 mm AMP in a 30 mm MOPS (3-(N-morpholino) propanesulfonic acid) buffer at pH 6.7. The apparent Km values for adenosine 3′-phosphate 5′-phosphosulfate and methyl-β-N-acetylglucosaminide were observed at 9.1 × 10−6m and 0.54 × 10−3m, respectively. The enzyme had more affinity for carbohydrate chains with a terminal GlcNAc residue than for methyl-β-N-acetylglucosaminide; it was unable to catalyze the transfer of sulfate to position 6 of the GlcNAc residue contained in a terminal Galβ1–4GlcNAc sequence. However, oligosaccharides with a nonreducing terminal HO3S-6GlcNAc were substrates for a β1–4 galactosyltransferase from human bronchial mucosa. These data point out that GlcNAc-6-O-sulfotransferase must act before β1–4 galactosylation in mucin-type oligosaccharide biosynthesis.