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Science 17 November 2006:
Vol. 314. no. 5802, pp. 1148 - 1150
DOI: 10.1126/science.1134351
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Reports

N-Linked Glycosylation of Folded Proteins by the Bacterial Oligosaccharyltransferase

Michael Kowarik,1*{dagger} Shin Numao,1* Mario F. Feldman,1*{ddagger} Benjamin L. Schulz,1 Nico Callewaert,1,2§ Eva Kiermaier,1 Ina Catrein,1 Markus Aebi1||

N-linked protein glycosylation is found in all domains of life. In eukaryotes, it is the most abundant protein modification of secretory and membrane proteins, and the process is coupled to protein translocation and folding. We found that in bacteria, N-glycosylation can occur independently of the protein translocation machinery. In an in vitro assay, bacterial oligosaccharyltransferase glycosylated a folded endogenous substrate protein with high efficiency and folded bovine ribonuclease A with low efficiency. Unfolding the eukaryotic substrate greatly increased glycosylation. We propose that in the bacterial system, glycosylation sites are located in flexible parts of folded proteins, whereas the eukaryotic cotranslational glycosylation evolved to a mechanism presenting the substrate in a flexible form before folding.

1 Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zurich, 8093 Zurich, Switzerland.
2 Zürich Glycomics Initiative (GlycoInit), ETH Zurich, 8093 Zurich, Switzerland.

* These authors contributed equally to this work.

{dagger} Present address: Glycovaxyn AG, Einsiedlerstrasse 31, 8820 Wädenswil, Switzerland.

{ddagger} Present address: Alberta Ingenuity Centre for Carbohydrate Science, Department of Biological Sciences, University of Alberta, Edmonton, AB, TG6 2E9, Canada.

§ Present address: Unit for Molecular Glycobiology, Department for Molecular Biomedical Research, VIB-Ghent University, Technologiepark 927, B-9052 Ghent-Zwijnaarde, Belgium.

|| To whom correspondence should be addressed. E-mail: aebi{at}micro.biol.ethz.ch

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Molecular Basis of S-layer Glycoprotein Glycan Biosynthesis in Geobacillus stearothermophilus.
K. Steiner, R. Novotny, D. B. Werz, K. Zarschler, P. H. Seeberger, A. Hofinger, P. Kosma, C. Schaffer, and P. Messner (2008)
J. Biol. Chem. 283, 21120-21133
   Abstract »    Full Text »    PDF »
Functional Characterization of Bacterial Oligosaccharyltransferases Involved in O-Linked Protein Glycosylation.
A. Faridmoayer, M. A. Fentabil, D. C. Mills, J. S. Klassen, and M. F. Feldman (2007)
J. Bacteriol. 189, 8088-8098
   Abstract »    Full Text »    PDF »
Structural context for protein N-glycosylation in bacteria: The structure of PEB3, an adhesin from Campylobacter jejuni.
E. S. Rangarajan, S. Bhatia, D. C. Watson, C. Munger, M. Cygler, A. Matte, and N. M. Young (2007)
Protein Sci. 16, 990-995
   Abstract »    Full Text »    PDF »


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Science. ISSN 0036-8075 (print), 1095-9203 (online)