[S8] 細菌エピジェネティクスとメタエピゲノミクス、DNAメチル化を中心に

[S8-6] 「メタエピゲノム」解析による環境中の細菌叢が持つ未知のDNAメチル化の探索

○平岡 聡史 (海洋研究開発機構（JAMSTEC）海洋機能利用部門 生命理工学センター 深海バイオリソース研究グループ)

DNA methylation plays important roles in prokaryotes, and their genomic landscapes have recently begun to be disclosed. However, our knowledge of prokaryotic methylation systems is focused on those of culturable microbes, which are rare in nature. Here, we have been used single-molecule real-time (SMRT) sequencing and circular consensus sequencing (CCS) techniques to reveal the ‘metaepigenomes’ of environmental microbial communities. In our analysis of microbial communities collected from Lake Biwa, Japan, 22 methylated motifs, including 9 novel ones, were revealed from 19 reconstructed draft genomes most of which are yet to be cultured. Also, we identified methyltransferase (MTase) genes likely responsible for methylation of the novel motifs, and confirmed the catalytic specificities of four of them via transformation experiments using synthetic genes. Besides this, we are now working on marine microbial communities collected from the North-West Pacific Ocean. We identified more than a hundred of methylated motifs and MTase genes including several novels ones from reconstructed genomes. These results demonstrated the effectiveness of the metaepigenomic approach showing advantages over culture-based methylation analyses, leading to a deeper understanding of the ecological impacts of DNA methylation on prokaryotes.