8VIW

Cryo-EM structure of heparosan synthase 2 from Pasteurella multocida with polysaccharide in the GlcNAc-T active site

Summary for 8VIW

• Entry DOI: 10.2210/pdb8viw/pdb
• Related: 8VH7 8VH8
• EMDB information: 43269
• Descriptor: Heparosan synthase B, beta-D-glucopyranuronic acid-(1-4)-2-deoxy-2-(sulfoamino)-alpha-D-glucopyranose-(1-4)-beta-D-glucopyranuronic acid-(1-4)-2-deoxy-2-(sulfoamino)-alpha-D-glucopyranose-(1-4)-beta-D-glucopyranuronic acid, MANGANESE (II) ION, ... (5 entities in total)
• Functional Keywords: polysaccharide synthase, complex, transferase
• Biological source: Pasteurella multocida
• Total number of polymer chains: 4
• Total formula weight: 265981.20

Authors

Krahn, J.M.,Pedersen, L.C.,Liu, J.,Stancanelli, E.,Borgnia, M.,Vivarette, E. (deposition date: 2024-01-05, release date: 2024-07-24, Last modification date: 2025-03-12)

Primary citation

Stancanelli, E.,Krahn, J.A.,Viverette, E.,Dutcher, R.,Pagadala, V.,Borgnia, M.J.,Liu, J.,Pedersen, L.C.
Structural and Functional Analysis of Heparosan Synthase 2 from Pasteurella multocida (PmHS2) to Improve the Synthesis of Heparin.
Acs Catalysis, 14:6577-6588, 2024

PubMed Abstract: Heparin is a widely used drug to treat thrombotic disorders in hospitals. Heparosan synthase 2 from (PmHS2) is a key enzyme used for the chemoenzymatic synthesis of heparin oligosaccharides. It has both activities: glucosaminyl transferase activity and glucuronyl transferase activity; however, the mechanism to carry out the glyco-oligomerization is unknown. Here, we report crystal structures of PmHS2 constructs with bound uridine diphosphate (UDP) and a cryo-EM structure of PmHS2 in complex with UDP and a heptasaccharide (NS 7-mer) substrate. Using a LC-MC analytical method, we discovered the enzyme displays both a two-step concerted oligomerization mode and a distributive oligomerization mode depending on the non-reducing end of the starting oligosaccharide primer. Removal of 7 amino acid residues from the C-terminus results in an enzymatically active monomer instead of dimer and loses the concerted oligomerization mode of activity. In addition, the monomer construct can transfer N-acetyl glucosamine at a substrate concentration that is ∼7-fold higher than wildtype enzyme. It was also determined that an F529A mutant can transfer an N-sulfo glucosamine (GlcNS) saccharide from a previously inactive UDP-GlcNS donor. Performing the glyco-transfer reaction at a high substrate concentration and the capability of using unnatural donors are desirable to simplify the chemoenzymatic synthesis to prepare heparin-based therapeutics.

PubMed: 39990868
DOI: 10.1021/acscatal.4c00677

Experimental method

ELECTRON MICROSCOPY (3.3 Å)