The 3- O -sulfation of heparan sulfate modulates protein binding and lyase degradation

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 118; no. 3
• Main Authors: Chopra, Pradeep, Joshi, Apoorva, Wu, Jiandong, Lu, Weigang, Yadavalli, Tejabhiram, Wolfert, Margreet A, Shukla, Deepak, Zaia, Joseph, Boons, Geert-Jan
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 19.01.2021
• Subjects: Physical Sciences; anti-Factor Xa; heparin lyases; herpes simplex virus 1; 3-O-sulfation; glycan microarray
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2012935118

Humans express seven heparan sulfate (HS) 3- -sulfotransferases that differ in substrate specificity and tissue expression. Although genetic studies have indicated that 3- -sulfated HS modulates many biological processes, ligand requirements for proteins engaging with HS modified by 3- -sulfate (3-OS) have been difficult to determine. In particular, the context in which the 3-OS group needs to be presented for binding is largely unknown. We describe herein a modular synthetic approach that can provide structurally diverse HS oligosaccharides with and without 3-OS. The methodology was employed to prepare 27 hexasaccharides that were printed as a glycan microarray to examine ligand requirements of a wide range of HS-binding proteins. The binding selectivity of antithrombin-III (AT-III) compared well with anti-Factor Xa activity supporting robustness of the array technology. Many of the other examined HS-binding proteins required an IdoA2S-GlcNS3S6S sequon for binding but exhibited variable dependence for the 2-OS and 6-OS moieties, and a GlcA or IdoA2S residue neighboring the central GlcNS3S. The HS oligosaccharides were also examined as inhibitors of cell entry by herpes simplex virus type 1, which, surprisingly, showed a lack of dependence of 3-OS, indicating that, instead of glycoprotein D (gD), they competitively bind to gB and gC. The compounds were also used to examine substrate specificities of heparin lyases, which are enzymes used for depolymerization of HS/heparin for sequence determination and production of therapeutic heparins. It was found that cleavage by lyase II is influenced by 3-OS, while digestion by lyase I is only affected by 2-OS. Lyase III exhibited sensitivity to both 3-OS and 2-OS.