The Effect of galE Gene Inactivation on Lipopolysaccharide Profile of Helicobacter pylori

Kwon, Dong-Hyeon; Woo, Jae-Soon; Perng, Cherng-Kang; Go, Mae F.; Graham, David Y.; El-Zaatari, F. A. K.

doi:10.1007/s002849900354

Cited by 29 publications

(24 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…LPS structure (4,5,46) and biochemical data (15,30,36,44) indicated that FlaA1 and WbpB were not LPS biosynthetic enzymes per se in H. pylori. Disruption of their genes nevertheless significantly reduced O-antigen production and resulted in the formation of altered core LPS (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Interestingly, neither the 4-keto intermediate nor its reduced derivative are present in the LPS of H. pylori (4,5,46). In addition, all genes involved in the biosynthesis of the precursors necessary for LPS assembly have been identified (30,36,44) and are distinct from flaA1 and wbpB. Consequently, although it is expected that flaA1 and wbpB might affect LPS synthesis based on sequence homologies, such an effect is not anticipated to occur directly via production of LPS sugar precursors.…”

mentioning

confidence: 99%

See 1 more Smart Citation

TheHelicobacter pylori flaA1andwbpBGenes Control Lipopolysaccharide and Flagellum Synthesis and Function

et al. 2004

View full text Add to dashboard Cite

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 potential redundancy of the reductase activity encoded by both genes. Both mutants were nonmotile, although the wbpB mutant still produced flagella. The defect in the flagellum functionality of this mutant was not due to a defect in flagellin glycosylation since flagellins from wild-type strain NCTC 11637 were shown not to be glycosylated. The flaA1 mutant produced flagellins but no flagellum. Overall, the similar phenotypes observed for both mutants and the complementation of the wbpB mutant by flaA1 suggest that both genes belong to the same biosynthesis pathway. The data also suggest that flaA1 and wbpB are at the interface between several pathways that govern the expression of different virulence factors. We propose that FlaA1 and WbpB synthesize sugar derivatives dedicated to the glycosylation of proteins which are involved in LPS and flagellum production and that glycosylation regulates the activity of these proteins.Helicobacter pylori is a spiral-shaped gram-negative microaerophilic bacterium that was first isolated from the human stomach in 1984 (42). It is estimated that 70% of the worldwide population is infected by this bacterium. Most infections are asymptomatic, but they can also lead to gastric ulcers and cancers (26,51,66,69). The relationship between colonization by H. pylori and the onset of the disease is not fully understood. Hence, it is important to identify essential bacterial virulence factors and elucidate their contribution to disease development.Several virulence factors contribute to the stringent host and tissue specificities exhibited by H. pylori (37). Among them, urease helps neutralize the acidic pH surrounding the bacteria and allows their survival in the gastric environment (21, 45). In addition, the spiral shape and unipolar flagella of H. pylori confer on the bacterium a corkscrew motion that enhances motility in the viscous gastric mucus (32, 33, 63) and is essential for host colonization (22,23,35). Lipopolysaccharide (LPS) is also important for the virulence of H. pylori since strains lacking the O antigen are significantly impaired in their capacity to colonize the murine stomach (40). The H. pylori O antigen is composed of N-acetyl-D-glucosamine, L-fucose, and D-galactose (4, 5, 46), which form structural motifs that are identical to human blood group antigens Lewis X, Y, and b (4,5,[46][47][48]....

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

TheHelicobacter pylori flaA1andwbpBGenes Control Lipopolysaccharide and Flagellum Synthesis and Function

et al. 2004

View full text Add to dashboard Cite

show abstract

“…In previous studies, the galE mutant of Vibrio cholerae, whose O antigen does not include galactose, did not have an altered LPS profile (26), while galE mutants of other bacteria, such as Neisseria meningitidis and Helicobacter pylori, were found to produce truncated LPS molecules that lacked galactose (16,19). Bramanti et al reported that galactose accounted for 25.3% of the total monosaccharides of LPS in P. gingivalis strain 33277 (4).…”

Section: Discussionmentioning

confidence: 99%

Porphyromonas gingivalis galEIs Involved in Lipopolysaccharide O-Antigen Synthesis and Biofilm Formation

2006

View full text Add to dashboard Cite

Porphyromonas gingivalis is a crucial component of complex plaque biofilms that form in the oral cavity, resulting in the progression of periodontal disease. To elucidate the mechanism of periodontal biofilm formation, we analyzed the involvement of several genes related to the synthesis of polysaccharides in P. gingivalis. Gene knockout P. gingivalis mutants were constructed by insertion of an ermF-ermAM cassette; among these mutants, the galE mutant showed some characteristic phenotypes involved in the loss of GalE activity. As expected, the galE mutant accumulated intracellular carbohydrates in the presence of 0.1% galactose and did not grow in the presence of galactose at a concentration greater than 1%, in contrast to the parental strain. Lipopolysaccharide (LPS) analysis indicated that the length of the O-antigen chain of the galE mutant was shorter than that of the wild type. It was also demonstrated that biofilms generated by the galE mutant had an intensity 4.5-fold greater than those of the wild type. Further, the galE mutant was found to be significantly susceptible to some antibiotics in comparison with the wild type. In addition, complementation of the galE mutation led to a partial recovery of the parental phenotypes. We concluded that the galE gene plays a pivotal role in the modification of LPS O antigen and biofilm formation in P. gingivalis and considered that our findings of a relationship between the function of the P. gingivalis galE gene and virulence phenotypes such as biofilm formation may provide clues for understanding the mechanism of pathogenicity in periodontal disease.

show abstract

“…Therefore, we constructed isogenic H. pylori P1 mutants defective in the galE gene (hp360) encoding a UDP-glucose-4-epimerase, or the pmi gene (also called rfbM or hp43) encoding a bifunctional mannose-6-phosphate isomerase/GDPmannose pyrophosphorylase, both of which are involved in LPS biosynthesis (8). The galE gene of strain P1 was disrupted with plasmid pGH26 (24), and the pmi gene was disrupted with plasmid pDHO25::TnMax5-3 (18). Both mutations resulted in the production of a RecA protein without an apparent modification (Fig.…”

Section: Size Variation Of Thementioning

confidence: 99%

The RecA Protein ofHelicobacter pyloriRequires a Posttranslational Modification for Full Activity

Fischer

Haas

2004

J Bacteriol

View full text Add to dashboard Cite

The RecA protein is a central component of the homologous recombination machinery and of the SOS system in most bacteria. In performing these functions, it is involved in DNA repair processes and plays an important role in natural transformation competence. This may be especially important in Helicobacter pylori, where an unusually high degree of microdiversity among strains is generated by homologous recombination. We have suggested previously that the H. pylori RecA protein is subject to posttranslational modifications that result in a slight shift in its electrophoretic mobility. Here we show that at least two genes downstream of recA are involved in this modification and that this process is dependent on genes involved in glycosylation and lipopolysaccharide biosynthesis. Site-directed mutagenesis of a putative glycosylation site results in production of an unmodified RecA protein. This posttranslational modification is not involved in membrane targeting or cell division functions but is necessary for the full function of RecA in DNA repair. Thus, it might be an adaptation to the specific requirements of H. pylori in its natural environment.The gram-negative bacterial pathogen Helicobacter pylori is the principal cause of chronic active gastritis and peptic ulcer disease and has been implicated in the development of gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer (29, 40). The very special habitat of H. pylori at the surface of gastric epithelial cells or in the mucus layer covering the epithelium suggests that this bacterium has evolved specialized features for adaptation. A comparison of the two published genome sequences shows a considerable diversity in gene content, with about 7% of all putative genes being strain specific (1). Moreover, some H. pylori strains display high mutation frequencies (3), and more diversity is created by horizontal gene transfer and free recombination between strains (41), although infections with multiple strains are not very common. Since H. pylori is naturally competent for transformation, horizontal gene transfer is supposed to occur mainly by this mechanism.Thus, homologous recombination is an important function which helps to generate diversity, but it is also involved in maintaining genome integrity and thus species barriers (28). These functions are achieved by a complex machinery which is highly regulated and which involves many proteins (9). The RecA protein is one of the central components of this machinery. One of its main functions is the recognition of stretches of single-stranded DNA, which are subsequently complexed by helical RecA filaments. In Escherichia coli, this filamentous form of RecA is activated as a coprotease that regulates cellular functions such as the SOS response or the induction of trans-lesion DNA synthesis. Both this coprotease activity and the recombination function are thought to play major roles in the bacterial response to DNA damage. The RecA protein of H. pylori has likewise been shown to be necessary for DNA repai...

show abstract

The Effect of galE Gene Inactivation on Lipopolysaccharide Profile of Helicobacter pylori

Cited by 29 publications

References 25 publications

TheHelicobacter pylori flaA1andwbpBGenes Control Lipopolysaccharide and Flagellum Synthesis and Function

TheHelicobacter pylori flaA1andwbpBGenes Control Lipopolysaccharide and Flagellum Synthesis and Function

Porphyromonas gingivalis galEIs Involved in Lipopolysaccharide O-Antigen Synthesis and Biofilm Formation

The RecA Protein ofHelicobacter pyloriRequires a Posttranslational Modification for Full Activity

Contact Info

Product

Resources

About