Molecular basis for glycan recognition and reaction priming of eukaryotic oligosaccharyltransferase.

Autor: Ramírez AS; Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland., de Capitani M; Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland., Pesciullesi G; Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland., Kowal J; Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland., Bloch JS; Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland., Irobalieva RN; Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland., Reymond JL; Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland., Aebi M; Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland., Locher KP; Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland. locher@mol.biol.ethz.ch.
Jazyk: angličtina
Zdroj: Nature communications [Nat Commun] 2022 Nov 26; Vol. 13 (1), pp. 7296. Date of Electronic Publication: 2022 Nov 26.
DOI: 10.1038/s41467-022-35067-x
Abstrakt: 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.
(© 2022. The Author(s).)
Databáze: MEDLINE
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