Research
Bacterial evolution is so rapid that bacterial strains can have very different cell physiology and pathogenicity even between strains of same species. I am revealing such differences by comparing bacterial strains from the aspect of genome context and epigenome context and seeking for application of the knowledge for the improvement of public health.
1. Genome rearranemgents
In addition to accumulation of single nucleotide mutations, large genome rearrangements such as insertion/deletion, substitution, inversion, translocation, and gene duplication are critical causes of evolution and lead to genome structure diversity.
Helicobacter pylori, bacteria infects human stomach, is known for its large genome variation depending of its geographical origin. I sequenced and conducted the genome comparison analysis of
H. pylori strians isolated from Japanese patients and revealed relationships between genome structure variation and evolution of species (Kawai et al, BMC Microbiology, 2011). I also found a new gene duplication mechanism which is associated with genome inversion and gene duplication (Furuta et al, PNAS, 2011).
2. Bacterial epigenetics
DNA modifications on genome sequences are known for their activity as regulator of gene expression, both in eukaryote and prokaryote. In prokaryote, genome DNA is methylated mainly by DNA methyltransferase enzymes which recognize specific target DNA sequence, usually longer than 4 nucleotides.
H. pylori has large number of DNA methyltransferase genes and has large diversity in target sequences for DNA methylation activity, inferred from informatic analysis of genome sequences and proved by methylome sequencing analysis (Furuta et al, PLoS ONE, 2011; Furuta et al, PLoS Genetics, 2014).