Helicobacter pylori physiology predicted from genomic comparison of two strains

Helicobacter pylori is a gram-negative bacteria which colonizes the gastric mucosa of humans and is implicated in a wide range of gastroduodenal disea ses. This paper reviews the physiology of this bacterium as predicted from the sequenced genomes of two unrelated strains and reconciles these predict ions with the literature. In general, the predicted capabilities are in goa d agreement with reported experimental observations. H. pylori is limited i n carbohydrate utilization and will use amino acids, for which it has trans porter systems, as sources of carbon. Energy can be generated by fermentati on and the bacterium possesses components necessary for both aerobic and an aerobic respiration. Sulfur metabolism is limited, whereas nitrogen metabol ism is extensive. There is active uptake of DNA via transformation and ampl e restriction-modification activities. The cell contains numerous outer mem brane proteins, some of which are porins or involved in iron uptake. Some o f these outer membrane proteins and the lipopolysaccharide may be regulated by a slipped-strand repair mechanism which probably results in phase varia tion and plays a role in colonization. In contrast to a commonly held belie f 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.