3vu0
From Proteopedia
Crystal structure of the C-terminal globular domain of oligosaccharyltransferase (AfAglB-S2, AF_0040, O30195_ARCFU) from Archaeoglobus fulgidus
Structural highlights
FunctionAGLB2_ARCFU Oligosaccharyl transferase (OST) that catalyzes the initial transfer of a defined glycan (a GalNAc-linked heptasaccharide composed of 4 Hex, 3 dHex and a sulfate for A.fulgidus AglB-S) 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] Publication Abstract from PubMedOligosaccharyltransferase (OST) is a membrane-bound enzyme that catalyzes the transfer of an oligosaccharide to an asparagine residue in glycoproteins. It possesses a binding pocket that recognizes Ser and Thr residues at the +2 position in the N-glycosylation consensus, Asn-X-Ser/Thr. We determined the crystal structures of the C-terminal globular domains of the catalytic subunits of two archaeal OSTs. A comparison with previously determined structures identified a segment with remarkable conformational plasticity, induced by crystal contact effects. We characterized its dynamic properties in solution by (15)N NMR relaxation analyses. Intriguingly, the mobile region contains the +2 Ser/Thr-binding pocket. In agreement, the flexibility restriction forced by an engineered disulfide crosslink abolished the enzymatic activity, and its cleavage fully restored activity. These results suggest the necessity of multiple conformational states in the reaction. The dynamic nature of the Ser/Thr pocket could facilitate the efficient scanning of N-glycosylation sequons along nascent polypeptide chains. Crystallographic and NMR evidence for flexibility in oligosaccharyltransferases and its catalytic significance.,Nyirenda J, Matsumoto S, Saitoh T, Maita N, Noda NN, Inagaki F, Kohda D Structure. 2013 Jan 8;21(1):32-41. doi: 10.1016/j.str.2012.10.011. Epub 2012 Nov , 21. PMID:23177926[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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