6XCR

NMR structure of Ost4 in DPC micelles

Summary for 6XCR

• Entry DOI: 10.2210/pdb6xcr/pdb
• NMR Information: BMRB: 30760
• Descriptor: Oligosaccharyltransferase (1 entity in total)
• Functional Keywords: transferase, membrane protein
• Biological source: Saccharomyces cerevisiae (strain YJM789) (Baker's yeast)
• Total number of polymer chains: 1
• Total formula weight: 5215.04

Authors

Chaudhary, B.P. (deposition date: 2020-06-09, release date: 2021-02-10, Last modification date: 2024-05-15)

Primary citation

Chaudhary, B.P.,Zoetewey, D.L.,McCullagh, M.J.,Mohanty, S.
NMR and MD simulations reveal the impact of the V23D mutation on the function of yeast oligosaccharyltransferase subunit Ost4.
Glycobiology, 31:838-850, 2021

PubMed Abstract: Asparagine-linked glycosylation, also known as N-linked glycosylation, is an essential and highly conserved co- and post-translational protein modification in eukaryotes and some prokaryotes. In the central step of this reaction, a carbohydrate moiety is transferred from a lipid-linked donor to the side-chain of a consensus asparagine in a nascent protein as it is synthesized at the ribosome. Complete loss of oligosaccharyltransferase (OST) function is lethal in eukaryotes. This reaction is carried out by a membrane-associated multisubunit enzyme, OST, localized in the endoplasmic reticulum. The smallest subunit, Ost4, contains a single membrane-spanning helix that is critical for maintaining the stability and activity of OST. Mutation of any residue from Met18 to Ile24 of Ost4 destabilizes the enzyme complex, affecting its activity. Here, we report solution nuclear magnetic resonance structures and molecular dynamics (MD) simulations of Ost4 and Ost4V23D in micelles. Our studies revealed that while the point mutation did not impact the structure of the protein, it affected its position and solvent exposure in the membrane mimetic environment. Furthermore, our MD simulations of the membrane-bound OST complex containing either WT or V23D mutant demonstrated disruption of most hydrophobic helix-helix interactions between Ost4V23D and transmembrane TM12 and TM13 of Stt3. This disengagement of Ost4V23D from the OST complex led to solvent exposure of the D23 residue in the hydrophobic pocket created by these interactions. Our study not only solves the structures of yeast Ost4 subunit and its mutant but also provides a basis for the destabilization of the OST complex and reduced OST activity.

PubMed: 33442744
DOI: 10.1093/glycob/cwab002

Experimental method

SOLUTION NMR