Crystallographic and NMR evidence for flexibility in oligosaccharyltransferases and its catalytic significance.
Structure
; 21(1): 32-41, 2013 Jan 08.
Article
in En
| MEDLINE
| ID: mdl-23177926
ABSTRACT
Oligosaccharyltransferase (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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Archaeal Proteins
/
Pyrococcus horikoshii
/
Hexosyltransferases
/
Membrane Proteins
Language:
En
Journal:
Structure
Journal subject:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
/
BIOTECNOLOGIA
Year:
2013
Document type:
Article
Affiliation country:
Japan