7e9s
From Proteopedia
Archaeal oligosaccharyltransferase AglB from Archaeoglobus fulgidus in complex with an inhibitory peptide and a dolichol-phosphate
Structural highlights
FunctionAGLB3_ARCFU Oligosaccharyl transferase (OST) that catalyzes the initial transfer of a defined glycan (a glucose-linked heptasaccharide composed of 3 Glc, 2 Man, 2 Gal and a sulfate for A.fulgidus AglB-L) from the lipid carrier dolichol-monophosphate to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains, the first step in protein N-glycosylation.[1] [2] [3] Publication Abstract from PubMedOligosaccharyltransferase (OST) catalyzes oligosaccharide transfer to the Asn residue in the N-glycosylation sequon, Asn-X-Ser/Thr, where Pro is strictly excluded at position X. Considering the unique structural properties of proline, this exclusion may not be surprising, but the structural basis for the rejection of Pro residues should be explained explicitly. Here we determined the crystal structure of an archaeal OST in a complex with a sequon-containing peptide and dolichol-phosphate to a 2.7 A resolution. The sequon part in the peptide forms two inter-chain hydrogen bonds with a conserved amino acid motif, TIXE. We confirmed the essential role of the TIXE motif and the adjacent regions by extensive alanine-scanning of the external loop 5. A Ramachandran plot revealed that the ring structure of the Pro side chain is incompatible with the varphi backbone dihedral angle around -150 degrees in the rigid sequon-TIXE structure. The present structure clearly provides the structural basis for the exclusion of Pro residues from the N-glycosylation sequon. The structure of an archaeal oligosaccharyltransferase provides insight into the strict exclusion of proline from the N-glycosylation sequon.,Taguchi Y, Yamasaki T, Ishikawa M, Kawasaki Y, Yukimura R, Mitani M, Hirata K, Kohda D Commun Biol. 2021 Aug 5;4(1):941. doi: 10.1038/s42003-021-02473-8. PMID:34354228[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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