View source for 9yq4


==Chlorella virus hyaluronan synthase bound to a proofreading UDP-GlcA==
<StructureSection load='9yq4' size='340' side='right'caption='[[9yq4]], [[Resolution|resolution]] 3.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9yq4]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Lama_glama Lama glama] and [https://en.wikipedia.org/wiki/Paramecium_bursaria_Chlorella_virus_CZ-2 Paramecium bursaria Chlorella virus CZ-2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9YQ4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9YQ4 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene>, <scene name='pdbligand=UGA:URIDINE-5-DIPHOSPHATE-GLUCURONIC+ACID'>UGA</scene>, <scene name='pdbligand=Y01:CHOLESTEROL+HEMISUCCINATE'>Y01</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=9yq4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9yq4 OCA], [https://pdbe.org/9yq4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9yq4 RCSB], [https://www.ebi.ac.uk/pdbsum/9yq4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9yq4 ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Hyaluronan (HA) is an essential polysaccharide of the vertebrate extracellular matrix. It serves as an adhesive, lubricant, signaling molecule, and spatial filler without which embryogenesis would not complete. HA is synthesized by a membrane-integrated glycosyltransferase (HAS) that polymerizes UDP-activated N-acetylglucosamine and glucuronic acid (GlcA) in an alternating fashion. The nascent HA chain is secreted across the plasma membrane during this process. How HAS couples these tasks remains poorly understood. Here, we employ a combination of structural biology, biochemistry and glycobiology to delineate how HAS recognizes and utilizes UDP-GlcA. Using single-particle cryo-EM, we reveal a two-step process by which HAS binds its substrate UDP-GlcA. Prior to proper insertion into the catalytic pocket, the substrate is bound in a proofreading pose that may increase substrate selectivity. This state is accompanied by conformational changes of active site residues surrounding the UDP-binding pocket and involves a pair of basic residues that sense the substrate's carboxyl group. Further, we establish that HAS is unable to catalyze UDP-GlcA turnover in the absence of an acceptor sugar, emphasizing the role of a priming GlcNAc in glycosyl transfer. Lastly, cryo-EM snapshots of a dodecylmaltoside molecule trapped in the active site provide novel insights into substrate promiscuity. Here, our studies demonstrate that HAS catalyzes semi-selective GlcA-transfer to non-canonical beta-linked acceptors.

Insights into substrate binding and utilization by hyaluronan synthase.,Stephens Z, Karasinska J, Zimmer J bioRxiv [Preprint]. 2025 Oct 18:2025.10.17.683186. doi: , 10.1101/2025.10.17.683186. PMID:41280022<ref>PMID:41280022</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 9yq4" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Lama glama]]
[[Category: Large Structures]]
[[Category: Paramecium bursaria Chlorella virus CZ-2]]
[[Category: Stephens Z]]
[[Category: Zimmer J]]