Duodenal ulcer promoting gene (DupA), plasticity region genes and sigma factors in H. pyloristrains from Nigeria

Introduction: Helicobacter pylori is a principal cause of gastric cancer. The aim of this study was to determine the prevalence and contribution of duodenal ulcer promoting gene A (dupA), the plasticity region genes and sigma factors in relation to their pathological expression of H. pylori infections in the Nigerian population. Methodology: Polymerase Chain Reaction was used to analyze a total of forty-nine H. pylori strains isolated from patients attending various endoscopic units in tertiary hospitals in Nigeria for complete dupA (G27 variant), jhp0917, jhp0918, other plasticity region genes jhp 914/917, jhp0914, jhp0940 and sigma factors. Results: PCR results indicated that the prevalence of complete dupA (G27 variants), jhp0917, jhp0918 and other plasticity region genes jhp0914, jhp0914/0917 and jhp0940 in the H. pylori strains were 4%, 53%, 88%, 73%, 12% and 0% respectively. The prevalence values of the sigma factors were 96%, 92%, 80% for rpoN, fliA and rpoD respectively. However, the endoscopic findings showed that erosion, normal mucosal, ulcer, hyperaemic stomach, mucosal atrophy and oedematous stomach in the patients where the H. pylori strains were isolated were 40.8%, 32.7%, 10.2%, 8.2%, 2.0% and 6.1% respectively. There was significant association between jhp0917, jhp914/917 and G27 variant and the endoscopic findings, while other plasticity genes showed no association with the endoscopic findings. Conclusion: These results suggest that the presence of jhp0917, jhp0914/917 and G27 variant could be used as marker to predict the pathological effect of severity in Nigeria patients with H. pylori infection.

Identification of residues involved in nucleotidyltransferase activity of JHP933 from helicobacter pyloriby site-directed mutagenesis

Helicobacter pylori is a well-known bacterial pathogen involved in the development of peptic ulcer, gastric adenocarcinoma and other forms of gastric cancer. Evidence has suggested that certain strain-specific genes in the plasticity region may play key roles in the pathogenesis of H. pylori-associated gastroduodenal diseases. Therefore there is considerable interest in the strain-specific genes located in the plasticity regions of H. pylori. JHP933 is encoded by the gene in the plasticity region of H. pylori strain J99. Recently, the crystal structure of JHP933 has confirmed it as a nucleotidyltransferase (NTase) superfamily protein and a putative active site has been proposed. However, no evidence from direct functional assay has been presented to confirm the active site and little is known about the functional mechanism of JHP933. Here, through superimposition with Cid1/NTP complex structures, we modelled the complex structures of JHP933 with different NTPs. Based on the models and using rational site-directed mutagenesis combined with enzymatic activity assays, we confirm the active site and identify several residues important for the nucleotidyl transferring function of JHP933. Furthermore, mutations of these active site residues result in the abolishment of the nucleotidyltransferase activity of JHP933. This work provides preliminary insight into the molecular mechanism underlying the pathophysiological role in H. pylori infection of JHP933 as a novel NTase superfamily protein.

Crystal structure of JHP933 from Helicobacter pylori J99

Helicobacter pylori infection is the main cause of chronic gastritis, gastric mucosal atrophy, peptic ulcer, and some forms of gastric cancer. There has been considerable interest in strain-specific genes found outside of the cag pathogenicity island, especially genes in the plasticity regions of H. pylori. In H. pylori strain J99, the plasticity region contains 48 genes ranging from jhp0914 to jhp0961. Because little is known about many of these genes in the plasticity region, further studies are necessary to elucidate their roles in H. pylori-associated pathogenesis. The JHP933 protein, encoded by the jhp0933 gene in the plasticity region of H. pylori J99, is one of the prevalently expressed proteins in some gastritis and peptic ulcer patients. However, its structure and function remain unknown. Here, we have determined the crystal structure of JHP933, revealing the first two-domain architecture of DUF1814 family. The N-terminal domain has the nucleotidyltransferase fold and the C-terminal domain is a helix bundle. Structural similarity of JHP933 to known nucleotidyltransferases is very remote, suggesting that it may function as a novel nucleotidyltransferase. It is expected that this study will facilitate functional characterization of JHP933 to obtain an insight into its role in pathogenesis by the H. pylori plasticity region.

The IntactdupACluster Is a More Reliable Helicobacter pylori Virulence Marker thandupAAlone

ABSTRACTThe duodenal ulcer promoting (dupA) gene, located in the plasticity region ofHelicobacter pylori, is associated with duodenal ulcer development.dupAwas predicted to form a type IV secretory system (T4SS) withvirgenes arounddupA(dupAcluster). We investigated the prevalence ofdupAanddupAclusters and clarified associations between thedupAcluster status and clinical outcomes in the U.S. population. In all, 245H. pyloristrains were examined using PCR to evaluate the status ofdupAand the adjacentvirgenes predicted to form T4SS, in addition to the status ofcagpathogenicity island (PAI). The associations betweendupAcluster status and interleukin-8 (IL-8) and IL-12 production were also examined. The presence ofdupAand all adjacentvirgenes were defined as a completedupAcluster. Many variations related to the status ofdupAanddupAcluster genes were identified. ConcurrentH. pyloriinfection and the presence of a completedupAcluster increases duodenal ulcer risk compared toH. pyloriinfection with incompletedupAcluster or without thedupAgene independent on thecagPAI status (adjusted odds ratio, 2.13; 95% confidence interval, 1.13 to 4.03). Gastric mucosal IL-8 levels were also significantly higher in the completedupAcluster group than in other groups (P= 0.01). In conclusion, although the causal relationship between thedupAcluster and duodenal ulcer development is not proved, the presence of a completedupAcluster but notdupAalone, is associated with duodenal ulcer development.