PMID:20333251

Citation	Hug, I, Couturier, MR, Rooker, MM, Taylor, DE, Stein, M and Feldman, MF (2010) Helicobacter pylori lipopolysaccharide is synthesized via a novel pathway with an evolutionary connection to protein N-glycosylation. PLoS Pathog. 6:e1000819
Abstract	Lipopolysaccharide (LPS) is a major component on the surface of Gram negative bacteria and is composed of lipid A-core and the O antigen polysaccharide. O polysaccharides of the gastric pathogen Helicobacter pylori contain Lewis antigens, mimicking glycan structures produced by human cells. The interaction of Lewis antigens with human dendritic cells induces a modulation of the immune response, contributing to the H. pylori virulence. The amount and position of Lewis antigens in the LPS varies among H. pylori isolates, indicating an adaptation to the host. In contrast to most bacteria, the genes for H. pylori O antigen biosynthesis are spread throughout the chromosome, which likely contributed to the fact that the LPS assembly pathway remained uncharacterized. In this study, two enzymes typically involved in LPS biosynthesis were found encoded in the H. pylori genome; the initiating glycosyltransferase WecA, and the O antigen ligase WaaL. Fluorescence microscopy and analysis of LPS from H. pylori mutants revealed that WecA and WaaL are involved in LPS production. Activity of WecA was additionally demonstrated with complementation experiments in Escherichia coli. WaaL ligase activity was shown in vitro. Analysis of the H. pylori genome failed to detect a flippase typically involved in O antigen synthesis. Instead, we identified a homolog of a flippase involved in protein N-glycosylation in other bacteria, although this pathway is not present in H. pylori. This flippase named Wzk was essential for O antigen display in H. pylori and was able to transport various glycans in E. coli. Whereas the O antigen mutants showed normal swimming motility and injection of the toxin CagA into host cells, the uptake of DNA seemed to be affected. We conclude that H. pylori uses a novel LPS biosynthetic pathway, evolutionarily connected to bacterial protein N-glycosylation.
Links	PubMed PMC2841628 Online version:10.1371/journal.ppat.1000819
Keywords	Cell Line; Epithelial Cells/metabolism; Epithelial Cells/microbiology; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Evolution, Molecular; Gastric Mucosa/cytology; Glycosylation; Glycosyltransferases/genetics; Glycosyltransferases/metabolism; Helicobacter pylori/enzymology; Helicobacter pylori/genetics; Humans; Lewis Blood-Group System/metabolism; Ligases/genetics; Ligases/metabolism; Lipopolysaccharides/biosynthesis; Mutation; O Antigens/genetics; O Antigens/metabolism; Peptidyl Transferases/metabolism; Phenotype; Phosphotransferases (Alcohol Group Acceptor)/genetics; Phosphotransferases (Alcohol Group Acceptor)/metabolism; Transferases (Other Substituted Phosphate Groups)/genetics; Transferases (Other Substituted Phosphate Groups)/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HELPJ:Q9ZJ30		GO:0016262:	ECO:0000315:				Figure 2 shows purified LPS proteins from H. pylori strain that was assayed with wild type, a mutant, and a complemented mutant phenotype. In the wild type and the complemented purification the LPS proteins isolated were smooth and had O-antigens. In the mutant phenotype lipid-A cores without O-antigens were expressed. This shows the WecA gene is partially responsible for LPS biosynthesis.	complete

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