Type IV secretion and H.pylori transformation

Helicobacter pylori colonizes the gastric mucosa of humans and, if left untreated, this will result in a lifelong gastritis. Although infection is usually asymptomatic, it can manifest clinically as peptic or duodenal ulcers. Additionally, colonization with H.pylori is believed to induce gastric atrophy and increase the risk of gastric cancer. New genotypes of H. pylori are generated by recombination fast enough to eliminate, essentially, the effect of clonal descent on the population structure [1]. The main mechanism of horizontal gene transfer used by H. pylori is natural transformation. The transformation systems of several Grampositive and Gram-negative species have been studied in some detail and are either dependent on the expression of pili or consist of proteins that resemble pilin subunits [2]. Recent data from Hofreuter et al., however, indicate that the transformation system of H. pylori is fundamentally different: rather than resembling pili, the structural core of the H. pylori DNA-translocation apparatus is related to type IV secretion systems [3,4].