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Title | Structural basis for heparan sulfate co-polymerase action by the EXT1-2 complex. |
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Journal, issue, pages | Nat Chem Biol, Vol. 19, Issue 5, Page 565-574, Year 2023 |
Publish date | Jan 2, 2023 |
Authors | Hua Li / Digantkumar Chapla / Robert A Amos / Annapoorani Ramiah / Kelley W Moremen / Huilin Li / |
PubMed Abstract | Heparan sulfate (HS) proteoglycans are extended (-GlcAβ1,4GlcNAcα1,4-) co-polymers containing decorations of sulfation and epimerization that are linked to cell surface and extracellular matrix ...Heparan sulfate (HS) proteoglycans are extended (-GlcAβ1,4GlcNAcα1,4-) co-polymers containing decorations of sulfation and epimerization that are linked to cell surface and extracellular matrix proteins. In mammals, HS repeat units are extended by an obligate heterocomplex of two exostosin family members, EXT1 and EXT2, where each protein monomer contains distinct GT47 (GT-B fold) and GT64 (GT-A fold) glycosyltransferase domains. In this study, we generated human EXT1-EXT2 (EXT1-2) as a functional heterocomplex and determined its structure in the presence of bound donor and acceptor substrates. Structural data and enzyme activity of catalytic site mutants demonstrate that only two of the four glycosyltransferase domains are major contributors to co-polymer syntheses: the EXT1 GT-B fold β1,4GlcA transferase domain and the EXT2 GT-A fold α1,4GlcNAc transferase domain. The two catalytic sites are over 90 Å apart, indicating that HS is synthesized by a dissociative process that involves a single catalytic site on each monomer. |
External links | Nat Chem Biol / PubMed:36593275 / PubMed Central |
Methods | EM (single particle) |
Resolution | 2.8 - 3.4 Å |
Structure data | EMDB-25035: Cryo-EM 3D map of the human Exostosin-1 and Exostosin-2 heterodimer EMDB-25036: Cryo-EM 3D map of the human Exostosin-1 and Exostosin-2 heterodimer in complex with a 4-sugar oligosaccharide acceptor analog EMDB-25037: Cryo-EM 3D map of the human Exostosin-1 and Exostosin-2 heterodimer in complex with a 7-sugar oligosaccharide acceptor analog EMDB-26701, PDB-7uqx: EMDB-26702, PDB-7uqy: |
Chemicals | ChemComp-NAG: ChemComp-UDP: ChemComp-MN: |
Source |
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Keywords | TRANSFERASE / exostosin1 / exostosin2 / glycosyltransferase / heparan sulfate / acceptor |