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The Role Of Protein Glycosylation In The Virulence Of The Gastric Pathogens Helicobacter Pylori And Campylobacter Jejuni, Alexandra Merkx-Jacques, C. Creuzenet

Alexandra Merkx-Jacques

H. pylori and C. jejuni are Gram-negative gastro-intestinal pathogens whose virulence is highly affected by protein glycosylation. The former causes gastric ulcers and cancer, while the latter causes enteritis and neurological disorders. Due to emerging drug-resistant strains, new treatments are needed.

In both bacteria, the flagellins are essential virulence factors glycosylated by pseudaminic acid (PA). We have identified and disrupted genes required for PA synthesis in both bacteria, and shown that this affects flagellin production. Further analysis and glycoprotein staining revealed that in H. pylori, the PA pathway is necessary for the glycosylation of proteins other than flagellins and …

Cj1121c, A Novel Udp-4-Keto-6-Deoxy-Glcnac C-4 Aminotransferase Essential For Protein Glycosylation And Virulence In Campylobacter Jejuni, Somalinga Vijayakumar, Alexandra Merkx-Jacques, Dinath Ratnayake, Irene Gryski, Ravinder Obhi, Sébastien Houle, Charles M Dozois, Carole Creuzenet

Alexandra Merkx-Jacques

Campylobacter jejuni produces glycoproteins that are essential for virulence. These glycoproteins carry diacetamidobacillosamine (DAB), a sugar that is not found in humans. Hence, the enzymes responsible for DAB synthesis represent potential therapeutic targets. We describe the biochemical characterization of Cj1121c, a putative aminotransferase encoded by the general protein glycosylation locus, to assess its role in DAB biosynthesis. By using overexpressed and affinity-purified enzyme, we demonstrate that Cj1121c has pyridoxal phosphate- and glutamate-dependent UDP-4-keto-6-deoxy-GlcNAc C-4 transaminase activity and produces UDP-4-amino-4,6-dideoxy-GlcNAc. This is consistent with a role in DAB biosynthesis and distinguishes Cj1121c from Cj1294, a homologous UDP-2-acetamido-2,6-dideoxy-beta-l-arabino-4-hexulose C-4 aminotransferase that we …

Investigating The Glycosylation Of Groel And Its Role In The Virulence Of Campylobacter Jejuni, Alexandra Merkx-Jacques, I. Gryski, C. Creuzenet

Alexandra Merkx-Jacques

Campylobacter jejuni is a food-borne human pathogen and a major cause of gastroenteritis, reactive arthritis and neurological disorders. Due to emerging drug resistant strains, new treatments and/or vaccines need to be developed.

Protein glycosylation, or the post-translational modification of proteins by sugar molecules, plays an important role in this bacterium's virulence including affecting cell-host interactions, immunogenicity and pathogenicity. C jejuni harbours numerous proteins glycosylated by a heptasaccharide containing diacetamidobacillosamine. Our laboratory investigates the enzymes required to make this sugar as well as the glycoproteins on which this glycan is found.

Analysis of C jejuni proteins by Western blot suggests that …

The Helicobacter Pylori Flaa1 And Wbpb Genes Control Lipopolysaccharide And Flagellum Synthesis And Function, Alexandra Merkx-Jacques, R. Obhi, G. Bethune, C. Creuzenet

Alexandra Merkx-Jacques

flaA1 and wbpB are conserved genes with unknown biological function in Helicobacter pylori. Since both genes are predicted to be involved in lipopolysaccharide (LPS) biosynthesis, flagellum assembly, or protein glycosylation, they could play an important role in the pathogenesis of H. pylori. To determine their biological role, both genes were disrupted in strain NCTC 11637. Both mutants exhibited altered LPS, with loss of most O-antigen and core modification, and increased sensitivity to sodium dodecyl sulfate compared to wild-type bacteria. These defects could be complemented in a gene-specific manner. Also, flaA1 could complement these defects in the wbpB mutant, suggesting a …