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N-linked glycosylation of folded proteins by the bacterial oligosaccharyltransferase.

Authors
  • 1
  • 1 Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zurich, 8093 Zurich, Switzerland. , (Switzerland)
Type
Published Article
Journal
Science
1095-9203
Publisher
American Association for the Advancement of Science (AAAS)
Publication Date
Volume
314
Issue
5802
Pages
1148–1150
Identifiers
PMID: 17110579
Source
Medline
License
Unknown

Abstract

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.

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