Broad spectrum O-linked protein glycosylation in the human pathogen Neisseria gonorrhoeae

Abstract

Protein glycosylation is an important element of biologic systems because of its significant effects on protein properties and functions. Although prominent within all domains of life, O-linked glycosylation systems modifying serine and threonine residues within bacteria and eukaryotes differ substantially in target protein selectivity. In particular, well-characterized bacterial systems have been invariably dedicated to modification of individual proteins or related subsets thereof. Here we characterize a general O-linked glycosylation system that targets structurally and functionally diverse groups of membrane-associated proteins in the Gram-negative bacterium Neisseria gonorrhoeae, the etiologic agent of the human disease gonorrhea. The 11 glycoproteins identified here are implicated in activities as varied as protein folding, disulfide bond formation, and solute uptake, as well as both aerobic and anaerobic respiration. Along with their common trafficking within the periplasmic compartment, the protein substrates share quasi-related domains bearing signatures of low complexity that were demonstrated to encompass sites of glycan occupancy. Thus, as in eukaryotes, the broad scope of this system is dictated by the relaxed specificity of the glycan transferase as well as the bulk properties and context of the proteintargeting signal rather than by a strict amino acid consensus sequence. Together, these findings reveal previously unrecognized commonalities linking O-linked protein glycosylation in distantly related life forms.bacteria ͉ glycoprotein ͉ pilin ͉ post-translational modification ͉ pgl

Characterization and Scope of S-layer Protein O-Glycosylation in Tannerella forsythia

“…Based on mass spectrometric and wet chemical analyses, however, COSY and TOCSY spectra enabled the identification of the monosaccharide units. 1 H chemical shifts and coupling constants allowed the analysis of anomeric configurations. ROESY spectra provided further information about spatial closeness of anomeric protons, which enabled the determination of the interglycosidic linkages.…”

“…In recent years, bacterial glycosylation systems have come under enhanced scrutiny because of the increasing frequencies with which they are seen in pathogenic and symbiont bacteria as well as their potential for exploitation in recombinant glycosylation engineering (1). Interestingly, in several of the investigated bacteria, a scenario of general glycosylation systems and of overlapping roles for distinct carbohydrate-active enzymes is evolving.…”

O-Glycosylation of the N-terminal Region of the Serine-rich Adhesin Srr1 of Streptococcus agalactiae Explored by Mass Spectrometry

“…gonorrheae (11). The second well-characterized type of transfer is sequential and arises in the cytoplasm: glycosyltransferases (GTs) 1 catalyze the transfer of monosaccharide residues, under a nucleotide-diphosphate activated form, in a stepwise manner to the protein.…”

Recent developments in bacterial protein glycan coupling technology and glycoconjugate vaccine design

“…However, both reports used N. meningitidis pilin as the acceptor protein and no information was provided on the ability of PglL to glycosylate other proteins in E. coli or on the presence of an acceptor sequon that is analogous to the one found for N-linked glycosylation. A report by Vik et al (2009) identified 11 O-linked glycoproteins in N. gonorrhoeae but did not find any consensus sequence surrounding the glycosylated amino acids. Instead, they identified the presence of domains of low complexity surrounding the glycosylated amino acids.…”