Physical map of the Helicobacter pylori Chromosome

ABSTRACT

Helicobacter pylori is a causative agent of type B gastritis and plays a central role in the pathogenesis of gastroduodenal ulcers and gastric cancer. Strategies for the control of H. pylori- induced gastroduodenal diseases based on conventional measures are still of limited utility. Therefore, it seems worthwhile to make a break-through as an alternative strategy by reviewing the host-parasite relationship of H. pylori infection on the basis of genomic structure. In this study, we tried to construct a physical map of H. pylori genome. Chromosomal DNA from a Korean prototype strain, H. pylori 51 was digested with 42 restriction endonucleases to identify restriction patterns suitable for mapping the genome. We identified three enzymes, ApaI, NotI and Sfil, which gave a small number of DNA fragments of higher molecular weight that were well resolved after pulsed-field gel electrophoresis. The H. pylori chromosome contained 7 ApaI fragments ranging from 167 to 311 kb, 7 NotI fragments ranging from 5 to 516 kb and 2 SfiI fragments of 332 and 1,347 kb in size. The genome size of the strain is 1,679 kb. A circular physical map of the H. pylori chromosome was constructed by aligning 3 kinds of restriction fragments by Southern blot analysis of simple ApaI, NotI and SfiI digests or double NotI/ApaI and NotI/SfiI digests with the various probes. When the physical map of H. pylori strain 51 compared with that of strain 26695 of which the cornplete genome sequence was reported, completely different restriction patterns were shown, which suggests the genomic diversity in H. pylori.