Helicobacter pyloriPhysiology Predicted from Genomic Comparison of Two Strains

Abstract

SUMMARY Helicobacter pylori is a gram-negative bacteria which colonizes the gastric mucosa of humans and is implicated in a wide range of gastroduodenal diseases. This paper reviews the physiology of this bacterium as predicted from the sequenced genomes of two unrelated strains and reconciles these predictions with the literature. In general, the predicted capabilities are in good agreement with reported experimental observations. H. pylori is limited in carbohydrate utilization and will use amino acids, for which it has transporter systems, as sources of carbon. Energy can be generated by fermentation, and the bacterium possesses components necessary for both aerobic and anaerobic respiration. Sulfur metabolism is limited, whereas nitrogen metabolism is extensive. There is active uptake of DNA via transformation and ample restriction-modification activities. The cell contains numerous outer membrane proteins, some of which are porins or involved in iron uptake. Some of these outer membrane proteins and the lipopolysaccharide may be regulated by a slipped-strand repair mechanism which probably results in phase variation and plays a role in colonization. In contrast to a commonly held belief that H. pylori is a very diverse species, few differences were predicted in the physiology of these two unrelated strains, indicating that host and environmental factors probably play a significant role in the outocme of H. pylori-related disease.

In vivo expression of the 25-kDa laminin-binding protein ofHelicobacter pylori

“…Importantly, during immunoblotting in the present study, conditions were employed to minimise any non-specific hydrophobic interactions [9,20] and, as in our previous investigation [9], the specificity of the interaction of laminin with the 25-kDa OMP was confirmed by complete inhibition of binding with 3-sialyllactose. Also, our stringently purified outer membrane preparations when analysed by SDS-PAGE and Coomassie blue staining indicated the absence of HpaA [22] and other known hydrophobic cytoplasmic proteins [23]. Furthermore, the purified 25-kDa laminin-binding protein gave identical results to those obtained with the outer membrane preparations.…”

Conservation and microdiversity of the phospholipase A (pldA) gene of Helicobacter pylori infecting dyspeptics from different countries

“…Comparisons of the complete genome sequences of two strains (26695 and J99) of H. pylori, provide a wealth of information about organisation, gene order and predicted proteomes [23,34,35]. Although the two sequenced isolates contained between 6 and 7% of genes speci¢c to each strain [23], the potential for inter-strain genome variation within common regions is enormous, as H. pylori appears to have a non-clonal (panmictic) population structure due to frequent recombination [36] and possibly to mutation [37].…”

Of microbe and man: determinants ofHelicobacter pylori-related diseases

“…Jhp0950 is found adjacent to Jhp0949 in the H. pylori J99 genome. Jhp0950, unlike Jhp0949, is not associated with an increased risk for duodenal ulcer (Alm et al, 1999;de Jonge et al, 2004a;Lehours et al, 2004a). Still, its association with disease supports the notion that H. pylori genes located within the plasticity region may be associated with virulence (Alm & Trust, 1999).…”

“…Comparison of the genome sequences from two individual strains has shown that approximately 6%-7% of the H. pylori genes present in one strain are absent from the other and vice versa (Alm et al, 1999). About half of the strain-specific genes are found in a hyper variable region; the plasticity zone.…”