title: Dissecting the substrate recognition of 3-O-sulfotransferase for the biosynthesis of anticoagulant heparin.
abstract: Heparin is a polysaccharide-based natural product that is used clinically as an anticoagulant drug. Heparan sulfate 3-O-sulfotransferase (3-OST) is an enzyme that transfers a sulfo group to the 3-OH position of a glucosamine unit. 3-OST is present in multiple isoforms, and the polysaccharides modified by these different isoforms perform distinct biological functions. 3-OST isoform 1 (3-OST-1) is the key enzyme for the biosynthesis of anticoagulant heparin. Here, we report the crystal structure of the ternary complex of 3-OST-1, 3'-phosphoadenosine 5'-phosphate, and a heptasaccharide substrate. Comparisons to previously determined structures of 3-OST-3 reveal unique binding modes used by the different isoforms of 3-OST for distinguishing the fine structures of saccharide substrates. Our data demonstrate that the saccharide substrates display distinct conformations when interacting with the different 3-OST isoforms. Site-directed mutagenesis data suggest that several key amino residues, including Lys259, Thr256, and Trp283 in 3-OST-3 and Arg268 in 3-OST-1, play important roles in substrate binding and specificity between isoforms. These results deepen our understanding of the biosynthetic mechanism of heparan sulfate and provide structural information for engineering enzymes for an enhanced biosynthetic approach to heparin production.
authors.affiliation: Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
authors.forename: Andrea F
authors.initials: AF
authors.lastname: Moon
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Xu
authors.forename: Susan M
authors.initials: SM
authors.lastname: Woody
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Krahn
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Linhardt
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.forename: Lars C
authors.initials: LC
authors.lastname: Pedersen
mesh_terms: D000595:Amino Acid Sequence; D000925:Anticoagulants / Q000378:metabolism*; D006493:Heparin / Q000096:biosynthesis*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D015238:Sulfotransferases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000925:Anticoagulants; D006493:Heparin; D015238:Sulfotransferases