[Diversity in genome and epigenome of Helicobacter pylori]

Helicobacter pylori infects human stomach and cause various gastric diseases including gastric cancer. The species is also known for rapid evolution and wide geographical diversity of genome sequence. Our team sequenced whole genome sequences of H. pylori strains isolated from Japanese patients and compared with whole genome sequences of H. pylori strains with other geographic origin and found that not only the gene repertoire but also genome structures and epigenetic modifications such as DNA methylations had large diversity with various mechanisms. Genome inversion events were geography specific and some of them were found to occur with gene duplication at their termini. DNA methylation states of H. pylori genomes suggested that they are diversified by both existence/absence repertoire of methyltransferase genes and by the movement of target recognition domain in the methyltransferase genes. Omics analysis revealed that methylation target sequence and transcriptome status are actually diversified by the domain sequence movement. We suggested that H. pylori utilizes these genome structure and methylome diversity for its adaptive evolution.