title: The N-glycan glycoprotein deglycosylation complex (Gpd) from Capnocytophaga canimorsus deglycosylates human IgG.
abstract: C. canimorsus 5 has the capacity to grow at the expenses of glycan moieties from host cells N-glycoproteins. Here, we show that C. canimorsus 5 also has the capacity to deglycosylate human IgG and we analyze the deglycosylation mechanism. We show that deglycosylation is achieved by a large complex spanning the outer membrane and consisting of the Gpd proteins and sialidase SiaC. GpdD, -G, -E and -F are surface-exposed outer membrane lipoproteins. GpdDEF could contribute to the binding of glycoproteins at the bacterial surface while GpdG is a endo-β-N-acetylglucosaminidase cleaving the N-linked oligosaccharide after the first N-linked GlcNAc residue. GpdC, resembling a TonB-dependent OM transporter is presumed to import the oligosaccharide into the periplasm after its cleavage from the glycoprotein. The terminal sialic acid residue of the oligosaccharide is then removed by SiaC, a periplasm-exposed lipoprotein in direct contact with GpdC. Finally, most likely degradation of the oligosaccharide proceeds sequentially from the desialylated non reducing end by the action of periplasmic exoglycosidases, including β-galactosidases, β-N-Acetylhexosaminidases and α-mannosidases.
authors: Biozentrum der Universität Basel, Basel, Switzerland.
authors: Francesco
authors: F
authors: Renzi
authors: Pablo
authors: P
authors: Manfredi
authors: Manuela
authors: M
authors: Mally
authors: Suzette
authors: S
authors: Moes
authors: Paul
authors: P
authors: Jenö
authors: Guy R
authors: GR
authors: Cornelis
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D002206:Capnocytophaga / Q000378:metabolism*; D002460:Cell Line; D006023:Glycoproteins / Q000378:metabolism*; D006031:Glycosylation; D016905:Gram-Negative Bacterial Infections; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D008074:Lipoproteins / Q000378:metabolism; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000378:metabolism; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009439:Neuraminidase / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D008363:alpha-Mannosidosis / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D006023:Glycoproteins; D007074:Immunoglobulin G; D008074:Lipoproteins; D011134:Polysaccharides; D009439:Neuraminidase; D001616:beta-Galactosidase; D001619:beta-N-Acetylhexosaminidases; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D019158:N-Acetylneuraminic Acid