Deciphering the substrate recognition mechanisms of the heparan sulfate 3-O-sulfotransferase-3

Abstract

The sulfation at the 3-OH position of a glucosamine saccharide is a rare modification, but is critically important for the biological activities of heparan sulfate polysaccharides. Heparan sulfate 3-O-sulfotransferase (3-OST),...

Structural and Substrate Specificity Analysis of 3-O-Sulfotransferase Isoform 5 to Synthesize Heparan Sulfate

“…3-OST-5 can generate 8-mers both with and without anticoagulant activity, depending on the saccharide sequences around the 3- O -sulfation site. Compared with previously published structures of 3-OST-1 and 3-OST-3, − we discovered that 3-OST-5 has a very similar structure in the active site and overall structure to 3-OST-1 and 3-OST-3. We also determined that the substrate specificity of 3-OST-5 is not only governed by the side chains from amino acid residues in the active site but also by uronic acids flanking both sides of the acceptor.…”

“…For the first time, we solved the structures of 3-OST-5 in complex with oligosaccharide substrates. Comparing the crystal structures of 3-OST isoforms 1, 3, and 5 with substrate bound, , we found that the active sites are very similar, although subtle structural differences exist. To our surprise, we discovered that the presence of IdoA2S reduces the reactivity of 3-OST-5 for modification.…”

“…(B) Substrate specificity of 3-OST-3. The IdoA2S saccharide unit near the acceptor site is in 2 S 0 skew boat confirmation based on the crystal structure . (C) Substrate specificity of 3-OST-5.…”

“…In 3-OST-3, both IdoA2S saccharides are in the skew boat ( 2 S 0 ) conformation. 21 This places the carboxylate on the IdoA2S at saccharide e within 3.7 Å of the 2-O-sulfo group on the IdoA2S at saccharide g. This accumulation of negative charge is partially alleviated by Lys259 for 3-OST-3, which hydrogen-bonds with both groups (Figure 6B). 31 Gly199 sits at the equivalent site in 3-OST-5 and is unable to form these interactions, resulting in a potential charge repulsion if IdoA2S was present at saccharide g. This would also place the 2-O-sulfo group within 4 Å of the N-sulfo group on the glucosamine at saccharide h. Finally, the 2 S 0 conformation results in a different position of the nonreducing end of the saccharide, which alters the trajectory of the substrate through the space between Ala306 and Ser120 in 3-OST-5, known as the gate structure.…”

Anion binding to a cationic europium(iii) probe enables the first real-time assay of heparan sulfotransferase activity

“…They exist in numerous isoforms with varying substrate preferences. 18 The sulfated products of this reaction play important roles in cell communication 19 and also feature in various pathologies including those of cancer, 20 Alzheimer's 21 and the mucopolysaccharidoses. 22 Heparan sulfotransferases belong to the wider group of sulfotransferases found across nature that use the universal sulfate donor compound PAPS (adenosine-3′-phosphate-5′-phosphosulfate), 23 and produce PAP (adenosine-3′,5′-diphosphate) as a by-product ( Scheme 1 ).…”