title: Recognition of protein-linked glycans as a determinant of peptidase activity.
abstract: The vast majority of proteins are posttranslationally altered, with the addition of covalently linked sugars (glycosylation) being one of the most abundant modifications. However, despite the hydrolysis of protein peptide bonds by peptidases being a process essential to all life on Earth, the fundamental details of how peptidases accommodate posttranslational modifications, including glycosylation, has not been addressed. Through biochemical analyses and X-ray crystallographic structures we show that to hydrolyze their substrates, three structurally related metallopeptidases require the specific recognition of O-linked glycan modifications via carbohydrate-specific subsites immediately adjacent to their peptidase catalytic machinery. The three peptidases showed selectivity for different glycans, revealing protein-specific adaptations to particular glycan modifications, yet always cleaved the peptide bond immediately preceding the glycosylated residue. This insight builds upon the paradigm of how peptidases recognize substrates and provides a molecular understanding of glycoprotein degradation.
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6, Canada.
authors.forename: Ilit
authors.initials: I
authors.lastname: Noach
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6, Canada.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ficko-Blean
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6, Canada.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Pluvinage
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6, Canada.
authors.forename: Christopher
authors.initials: C
authors.lastname: Stuart
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6, Canada.
authors.forename: Meredith L
authors.initials: ML
authors.lastname: Jenkins
authors.affiliation: Human Health Therapeutics, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
authors.forename: Denis
authors.initials: D
authors.lastname: Brochu
authors.affiliation: Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada.
authors.forename: Nakita
authors.initials: N
authors.lastname: Buenbrazo
authors.affiliation: Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada.
authors.forename: Warren
authors.initials: W
authors.lastname: Wakarchuk
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6, Canada.
authors.forename: John E
authors.initials: JE
authors.lastname: Burke
authors.affiliation: Human Health Therapeutics, National Research Council Canada, Ottawa, ON K1A 0R6, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Gilbert
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 3P6, Canada; boraston@uvic.ca.
authors.forename: Alisdair B
authors.initials: AB
authors.lastname: Boraston
mesh_terms: D004926:Escherichia coli / Q000235:genetics; D060748:Fetuins / Q000378:metabolism; D006020:Glycopeptides / Q000378:metabolism; D006031:Glycosylation; D009077:Mucins / Q000378:metabolism; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational
chemical_list: D060748:Fetuins; D006020:Glycopeptides; D009077:Mucins; D011134:Polysaccharides; D010447:Peptide Hydrolases
keywords: O-glycopeptidase; O-glycosylation; glycoprotein; metallopeptidase