1RKL

NMR structure of yeast oligosaccharyltransferase subunit Ost4p

Summary for 1RKL

• Entry DOI: 10.2210/pdb1rkl/pdb
• NMR Information: BMRB: 6056
• Descriptor: Dolichyl-diphosphooligosaccharide--protein glycosyltransferase 4 kDa subunit (1 entity in total)
• Functional Keywords: membrane protein, transferase
• Cellular location: Endoplasmic reticulum membrane; Single-pass membrane protein: Q99380
• Total number of polymer chains: 1
• Total formula weight: 3986.70

Authors

Zubkov, S.,Lennarz, W.J.,Mohanty, S. (deposition date: 2003-11-21, release date: 2004-03-23, Last modification date: 2024-05-22)

Primary citation

Zubkov, S.,Lennarz, W.J.,Mohanty, S.
Structural basis for the function of a minimembrane protein subunit of yeast oligosaccharyltransferase
Proc.Natl.Acad.Sci.USA, 101:3821-3826, 2004

PubMed Abstract: N-glycosylation of proteins is an essential, highly conserved modification reaction that occurs in all eukaryotes and some prokaryotes. This process is catalyzed by oligosaccharyltransferase (OT), a multisubunit enzyme localized in the endoplasmic reticulum. Complete loss of N-glycosylation is lethal in all organisms. In Saccharomyces cerevisiae, OT is composed of nine nonidentical membrane proteins. Here, we report the atomic structure of an OT subunit from S. cerevisiae, Ost4p. This unusually small membrane protein containing only 36 residues folds into a well formed, kinked helix in the model-membrane solvent system used in this study. The residues critical for the OT activity and the stability of Stt3p-Ost4p-Ost3p subcomplex are located in helix alpha2, the larger cytosolic half of this kinked helix. The residues known to disrupt Ost4p-Stt3p complex form a well defined ridge in the 3D structure. Taking together prior mutational studies and the NMR structure of Ost4p, we propose that in the OT complex Stt3p is packed against the alpha 2-helix of Ost4p by using a "ridges-into-grooves" model, with Met-18, Leu-21, and Ile-24 as the packing interface on one face, whereas Ost3p is involved in interactions with Met-19, Thr-20, Ile-22, and Val-23 on the other face.

PubMed: 15001703
DOI: 10.1073/pnas.0400512101

Experimental method

SOLUTION NMR