A ROLE OF LYS(614) IN THE SULFOTRANSFERASE ACTIVITY OF HUMAN HEPARAN-SULFATE N-DEACETYLASE N-SULFOTRANSFERASE/

An active sulfotransferase (ST, residues 558-882) domain of the human heparan sulfate N-deacetylase/N-sulfotransferase (hHSNST) has been ide ntified by aligning the amino acid sequence of hHSNST to that of mouse estrogen sulfotransferase (EST), The bacterially expressed ST domain transfers the 5'-sulfuryl group of 3'-phosphoadenosine-5'-phosphosulfa te (PAPS) to only deacetylated heparin with an efficiency similar to t hat previously reported for the purified rat HSNST. Moreover, the K-m, K-PAPS (2.1 mu M) of the ST domain is also similar to that of the rat enzyme. Lys(48) is a key residue in mEST catalysis, The residue corres ponding to Lys(48) is conserved in all known heparan sulfate sulfotran sferases (Lys(614) in the ST domain of hHSNST). Mutation of Lys(614) t o Ala abolishes N-sulfotransferase activity, indicating an important c atalytic role of Lys(614) in the ST domain. Crystals of the ST domain have been grown (orthorhombic space group P2(1)2(1)2) with diffraction to 2.5 A resolution. (C) 1998 Federation of European Biochemical Soci eties.