Removal of the outer Kdo from Helicobacter pylori lipopolysaccharide and its impact on the bacterial surface.
Helicobacter pylori produces a unique surface lipopolysaccharide (LPS) characterized by strikingly low endotoxicity that is thought to aid the organism in evading the host immune response. This reduction in endotoxicity is predicted to arise from the modification of the Kdo-lipid A domain of Helicobacter LPS by a series of membrane bound enzymes including a Kdo (3-deoxy-d-manno-octulosonic acid) hydrolase responsible for the modification of the core oligosaccharide. Here, we report that Kdo hydrolase activity is dependent upon a putative two-protein complex composed of proteins Hp0579 and Hp0580. Inactivation of Kdo hydrolase activity produced two phenotypes associated with cationic antimicrobial peptide resistance and O-antigen expression. Kdo hydrolase mutants were highly sensitive to polymyxin B, which could be attributed to a defect in downstream modifications to the lipid A 4'-phosphate group. Production of a fully extended O-antigen was also diminished in a Kdo hydrolase mutant, with a consequent increase in core-lipid A. Finally, expression of O-antigen Lewis X and Y epitopes, known to mimic glycoconjugates found on human tissues, was also affected. Taken together, we have demonstrated that loss of Kdo hydrolase activity affects all three domains of H. pylori LPS, thus highlighting its role in the maintenance of the bacterial surface.
Stead
Christopher M
CM
Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, GA 30912, USA.
Zhao
Jinshi
J
Raetz
Christian R H
CR
Trent
M Stephen
MS
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D055786:Gene Knockout Techniques; D016480:Helicobacter pylori / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism*; D007983:Lewis Blood Group Antigens / Q000378:metabolism; D016256:Lewis X Antigen / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism*; D019081:O Antigens / Q000096:biosynthesis; D011112:Polymyxin B / Q000494:pharmacology; D013400:Sugar Acids / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D007983:Lewis Blood Group Antigens; D016256:Lewis X Antigen; C094162:Lewis Y antigen; D008070:Lipopolysaccharides; D019081:O Antigens; D013400:Sugar Acids; C442865:lipopolysaccharide, Helicobacter pylori; C002532:2-keto-3-deoxyoctonate; D006867:Hydrolases; D011112:Polymyxin B