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==Cryo-EM structure of the yeast oligosaccharyltransferase (OST) complex==
==Cryo-EM structure of the yeast oligosaccharyltransferase (OST) complex==
<StructureSection load='6ezn' size='340' side='right'caption='[[6ezn]], [[Resolution|resolution]] 3.30&Aring;' scene=''>
<SX load='6ezn' size='340' side='right' viewer='molstar' caption='[[6ezn]], [[Resolution|resolution]] 3.30&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
<table><tr><td colspan='2'>[[6ezn]] is a 8 chain structure with sequence from [http://en.wikipedia.org/wiki/Baker's_yeast Baker's yeast]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6EZN OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6EZN FirstGlance]. <br>
<table><tr><td colspan='2'>[[6ezn]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae_S288C Saccharomyces cerevisiae S288C]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6EZN OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6EZN FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=CPL:1-PALMITOYL-2-LINOLEOYL-SN-GLYCERO-3-PHOSPHOCHOLINE'>CPL</scene>, <scene name='pdbligand=MAN:ALPHA-D-MANNOSE'>MAN</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=PTY:PHOSPHATIDYLETHANOLAMINE'>PTY</scene></td></tr>
</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='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Dolichyl-diphosphooligosaccharide--protein_glycotransferase Dolichyl-diphosphooligosaccharide--protein glycotransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.99.18 2.4.99.18] </span></td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=CPL:1-PALMITOYL-2-LINOLEOYL-SN-GLYCERO-3-PHOSPHOCHOLINE'>CPL</scene>, <scene name='pdbligand=MAN:ALPHA-D-MANNOSE'>MAN</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=PTY:PHOSPHATIDYLETHANOLAMINE'>PTY</scene></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=6ezn FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6ezn OCA], [http://pdbe.org/6ezn PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6ezn RCSB], [http://www.ebi.ac.uk/pdbsum/6ezn PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6ezn ProSAT]</span></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=6ezn FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6ezn OCA], [https://pdbe.org/6ezn PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6ezn RCSB], [https://www.ebi.ac.uk/pdbsum/6ezn PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6ezn ProSAT]</span></td></tr>
</table>
</table>
== Function ==
== Function ==
[[http://www.uniprot.org/uniprot/STT3_YEAST STT3_YEAST]] Catalytic subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity.<ref>PMID:12359722</ref>  [[http://www.uniprot.org/uniprot/OST3_YEAST OST3_YEAST]] Essential subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity. [[http://www.uniprot.org/uniprot/OSTB_YEAST OSTB_YEAST]] Essential subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity. [[http://www.uniprot.org/uniprot/OST2_YEAST OST2_YEAST]] Essential subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity. [[http://www.uniprot.org/uniprot/OSTD_YEAST OSTD_YEAST]] Essential subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity. [[http://www.uniprot.org/uniprot/OST1_YEAST OST1_YEAST]] Essential subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity. [[http://www.uniprot.org/uniprot/OST4_YEAST OST4_YEAST]] Essential subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity. OST4 is required for recruitment of OST3 or OST6 to the OST complex. It is essential for cell growth at 37 but not at 25 degrees Celsius. [[http://www.uniprot.org/uniprot/OST5_YEAST OST5_YEAST]] Essential subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity.  
[https://www.uniprot.org/uniprot/OST1_YEAST OST1_YEAST] Essential subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide from a lipid-linked oligosaccharide donor to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity.
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== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
Oligosaccharyltransferase (OST) is an essential membrane protein complex in the Endoplasmic Reticulum, where it transfers an oligosaccharide from a dolichol-pyrophosphate-activated donor to glycosylation sites of secretory proteins. We here describe the atomic structure of yeast OST determined by cryo-EM, revealing a conserved subunit arrangement. The active site of the catalytic STT3 subunit points away from the center of the complex, allowing unhindered access to substrates. The dolichol-pyrophosphate moiety binds to a lipid-exposed groove of STT3, while two non-catalytic subunits and an ordered N-glycan form a membrane-proximal pocket for the oligosaccharide. The acceptor polypeptide site faces an oxidoreductase domain in standalone OST complexes or is immediately adjacent to the translocon, suggesting how eukaryotic OSTs efficiently glycosylate a large number of polypeptides prior to their folding.
Oligosaccharyltransferase (OST) is the central enzyme of N-linked protein glycosylation. It catalyzes the transfer of a pre-assembled glycan, GlcNAc(2)Man(9)Glc(3), from a dolichyl-pyrophosphate donor to acceptor sites in secretory proteins in the lumen of the endoplasmic reticulum. Precise recognition of the fully assembled glycan by OST is essential for the subsequent quality control steps of glycoprotein biosynthesis. However, the molecular basis of the OST-donor glycan interaction is unknown. Here we present cryo-EM structures of S. cerevisiae OST in distinct functional states. Our findings reveal that the terminal glucoses (Glc(3)) of a chemo-enzymatically generated donor glycan analog bind to a pocket formed by the non-catalytic subunits WBP1 and OST2. We further find that binding either donor or acceptor substrate leads to distinct primed states of OST, where subsequent binding of the other substrate triggers conformational changes required for catalysis. This alternate priming allows OST to efficiently process closely spaced N-glycosylation sites.


Structure of the yeast oligosaccharyltransferase complex gives insight into eukaryotic N-glycosylation.,Wild R, Kowal J, Eyring J, Ngwa EM, Aebi M, Locher KP Science. 2018 Jan 4. pii: science.aar5140. doi: 10.1126/science.aar5140. PMID:29301962<ref>PMID:29301962</ref>
Molecular basis for glycan recognition and reaction priming of eukaryotic oligosaccharyltransferase.,Ramirez AS, de Capitani M, Pesciullesi G, Kowal J, Bloch JS, Irobalieva RN, Reymond JL, Aebi M, Locher KP Nat Commun. 2022 Nov 26;13(1):7296. doi: 10.1038/s41467-022-35067-x. PMID:36435935<ref>PMID:36435935</ref>


From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Glycosyltransferase 3D structures|Glycosyltransferase 3D structures]]
== References ==
== References ==
<references/>
<references/>
__TOC__
__TOC__
</StructureSection>
</SX>
[[Category: Baker's yeast]]
[[Category: Dolichyl-diphosphooligosaccharide--protein glycotransferase]]
[[Category: Large Structures]]
[[Category: Large Structures]]
[[Category: Aebi, M]]
[[Category: Saccharomyces cerevisiae S288C]]
[[Category: Eyring, J]]
[[Category: Aebi M]]
[[Category: Kowal, J]]
[[Category: Eyring J]]
[[Category: Locher, K P]]
[[Category: Kowal J]]
[[Category: Ngwa, E M]]
[[Category: Locher KP]]
[[Category: Wild, R]]
[[Category: Ngwa EM]]
[[Category: Membrane protein]]
[[Category: Wild R]]
[[Category: N-linked glycosylation]]
[[Category: Oligosaccharyltransferase]]
[[Category: Ost complex]]
[[Category: Yeast]]

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