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.

NMR-based Structural Analysis of the Complete Rough-type Lipopolysaccharide Isolated from Capnocytophaga canimorsus

“…All assignments of the NOE signals were further corroborated by data obtained from the HMBC spectrum ( Table 2). The positions of the two P-Etn residues in 1 were identified from the chemical shifts of the carbon resonances in the HSQC spectrum ( 8.0 Hz, ␦ C 104.5 ppm), all sugars were found to be ␣-linked. ROESY and HMBC experiments showed identical linkages as identified in the NMR spectra of the hexasaccharide 1 described above.…”

Bacterial chitinases and chitin-binding proteins as virulence factors

“…They are increasingly being recognized as virulence factors of bacterial pathogens and examples include enzymes belonging to GH2 galactosidases, GH13 pullulanases, GH18 endo-b-N-acetylglucosaminidases, GH20 b-hexosaminidases and b-N-acetylglucosaminidases, GH30 glycosylceramidases, GH33 sialidases, GH73 muramidases/lysozymes, GH84 hyaluronidases and GH101 N-acetylgalactosidases (Canard et al, 1994;Garbe & Collin, 2012;Kim et al, 2009;Lenz et al, 2003;van Bueren et al, 2007;Renzi et al, 2011;Sjögren et al, 2011).…”

Endo-N-Acetyl-β-D-Glucosaminidases and Peptide-N4-(N-acetyl-β-D-Glucosaminyl) Asparagine Amidases: More Than Just Tools

“…A surprising feature of C. canimorsus is the capacity to feed by foraging the glycan moieties of glycoproteins from animal cells, including phagocytes [97] and can also de-N-glycosylate human IgG, reinforcing the idea that this property of harvesting host glycoproteins may contribute to pathogenesis. This first characterised complete de-N-glycosylation system belongs to a large family of systems devoted to foraging complex glycans, found exclusively in the Capnocytophaga-Flavobacteria-Bacteroides group [97].…”