6C26

The Cryo-EM structure of a eukaryotic oligosaccharyl transferase complex

Summary for 6C26

• Entry DOI: 10.2210/pdb6c26/pdb
• EMDB information: 7336
• Descriptor: Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit STT3, beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, (4R,7R)-4-hydroxy-N,N,N-trimethyl-4,9-dioxo-7-[(undecanoyloxy)methyl]-3,5,8-trioxa-4lambda~5~-phosphadocosan-1-aminium, ... (12 entities in total)
• Functional Keywords: complex, transferase, glycosylation
• Biological source: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast); More
• Total number of polymer chains: 8
• Total formula weight: 291728.51

Authors

Bai, L.,Li, H. (deposition date: 2018-01-06, release date: 2018-01-31, Last modification date: 2024-10-23)

Primary citation

Bai, L.,Wang, T.,Zhao, G.,Kovach, A.,Li, H.
The atomic structure of a eukaryotic oligosaccharyltransferase complex.
Nature, 555:328-333, 2018

PubMed Abstract: N-glycosylation is a ubiquitous modification of eukaryotic secretory and membrane-bound proteins; about 90% of glycoproteins are N-glycosylated. The reaction is catalysed by an eight-protein oligosaccharyltransferase (OST) complex that is embedded in the endoplasmic reticulum membrane. Our understanding of eukaryotic protein N-glycosylation has been limited owing to the lack of high-resolution structures. Here we report a 3.5 Å resolution cryo-electron microscopy structure of the Saccharomyces cerevisiae OST complex, revealing the structures of subunits Ost1-Ost5, Stt3, Wbp1 and Swp1. We found that seven phospholipids mediate many of the inter-subunit interactions, and an Stt3 N-glycan mediates interactions with Wbp1 and Swp1 in the lumen. Ost3 was found to mediate the OST-Sec61 translocon interface, funnelling the acceptor peptide towards the OST catalytic site as the nascent peptide emerges from the translocon. The structure provides insights into co-translational protein N-glycosylation, and may facilitate the development of small-molecule inhibitors that target this process.

PubMed: 29466327
DOI: 10.1038/nature25755

Experimental method

ELECTRON MICROSCOPY (3.5 Å)