title: N-linked glycosylation of folded proteins by the bacterial oligosaccharyltransferase.
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.
authors.affiliation: Institute of Microbiology, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zurich, 8093 Zurich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Kowarik
authors.forename: Shin
authors.initials: S
authors.lastname: Numao
authors.forename: Mario F
authors.initials: MF
authors.lastname: Feldman
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Schulz
authors.forename: Nico
authors.initials: N
authors.lastname: Callewaert
authors.forename: Eva
authors.initials: E
authors.lastname: Kiermaier
authors.forename: Ina
authors.initials: I
authors.lastname: Catrein
authors.forename: Markus
authors.initials: M
authors.lastname: Aebi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D016123:Campylobacter jejuni; D002417:Cattle; D004926:Escherichia coli; D006023:Glycoproteins / Q000378:metabolism*; D006031:Glycosylation; D006602:Hexosyltransferases / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D017510:Protein Folding; D021381:Protein Transport; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006023:Glycoproteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase