View source for 6snh


==Cryo-EM structure of yeast ALG6 in complex with 6AG9 Fab and Dol25-P-Glc==
<StructureSection load='6snh' size='340' side='right'caption='[[6snh]], [[Resolution|resolution]] 3.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6snh]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Atcc_18824 Atcc 18824] and [http://en.wikipedia.org/wiki/Synthetic_construct_sequences Synthetic construct sequences]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6SNH OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6SNH FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=LMH:glucosyl-dolichol+phosphate'>LMH</scene></td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">ALG6, YOR002W, UNA544 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 ATCC 18824])</td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Dolichyl-P-Glc:Man(9)GlcNAc(2)-PP-dolichol_alpha-1,3-glucosyltransferase Dolichyl-P-Glc:Man(9)GlcNAc(2)-PP-dolichol alpha-1,3-glucosyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.267 2.4.1.267] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6snh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6snh OCA], [http://pdbe.org/6snh PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6snh RCSB], [http://www.ebi.ac.uk/pdbsum/6snh PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6snh ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/ALG6_YEAST ALG6_YEAST]] Adds the first glucose residue to the lipid-linked oligosaccharide precursor for N-linked glycosylation. Transfers glucose from dolichyl phosphate glucose (Dol-P-Glc) onto the lipid-linked oligosaccharide Man(9)GlcNAc(2)-PP-Dol.<ref>PMID:8877369</ref>  
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
In eukaryotic protein N-glycosylation, a series of glycosyltransferases catalyse the biosynthesis of a dolichylpyrophosphate-linked oligosaccharide before its transfer onto acceptor proteins(1). The final seven steps occur in the lumen of the endoplasmic reticulum (ER) and require dolichylphosphate-activated mannose and glucose as donor substrates(2). The responsible enzymes-ALG3, ALG9, ALG12, ALG6, ALG8 and ALG10-are glycosyltransferases of the C-superfamily (GT-Cs), which are loosely defined as containing membrane-spanning helices and processing an isoprenoid-linked carbohydrate donor substrate(3,4). Here we present the cryo-electron microscopy structure of yeast ALG6 at 3.0 A resolution, which reveals a previously undescribed transmembrane protein fold. Comparison with reported GT-C structures suggests that GT-C enzymes contain a modular architecture with a conserved module and a variable module, each with distinct functional roles. We used synthetic analogues of dolichylphosphate-linked and dolichylpyrophosphate-linked sugars and enzymatic glycan extension to generate donor and acceptor substrates using purified enzymes of the ALG pathway to recapitulate the activity of ALG6 in vitro. A second cryo-electron microscopy structure of ALG6 bound to an analogue of dolichylphosphate-glucose at 3.9 A resolution revealed the active site of the enzyme. Functional analysis of ALG6 variants identified a catalytic aspartate residue that probably acts as a general base. This residue is conserved in the GT-C superfamily. Our results define the architecture of ER-luminal GT-C enzymes and provide a structural basis for understanding their catalytic mechanisms.

Structure and mechanism of the ER-based glucosyltransferase ALG6.,Bloch JS, Pesciullesi G, Boilevin J, Nosol K, Irobalieva RN, Darbre T, Aebi M, Kossiakoff AA, Reymond JL, Locher KP Nature. 2020 Feb 26. pii: 10.1038/s41586-020-2044-z. doi:, 10.1038/s41586-020-2044-z. PMID:32103179<ref>PMID:32103179</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6snh" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Atcc 18824]]
[[Category: Large Structures]]
[[Category: Synthetic construct sequences]]
[[Category: Aebi, M]]
[[Category: Bloch, J S]]
[[Category: Boilevin, J]]
[[Category: Darbre, T]]
[[Category: Irobalieva, R N]]
[[Category: Kossiakoff, A A]]
[[Category: Locher, K P]]
[[Category: Nosol, K]]
[[Category: Pesciullesi, G]]
[[Category: Reymond, J L]]
[[Category: Glucosyltransferase]]
[[Category: Glycosyltransferase]]
[[Category: Gt-c]]
[[Category: Membrane protein]]
[[Category: N-glycosylation]]