第75回東京医科歯科大学
　　生体材料工学研究所　IBBセミナー　　
　　　　　日時：　２００７年　10月17日　場所：生材研　セミナー室にて

Covalent modification of DNA, such as cytosine methylation, can induce heritable gene silencing. If epigenetic modifications can be specifically targeted, new approaches to transcriptional therapy should result. To address this challenge we sought to design methyltransferases that would act only at a desired site by adapting the sequence-enabled assembly strategy. We hypothesized that a functional and site-specific enzyme could be self-assembled on a particular DNA sequence using zinc finger proteins (ZFPs) appropriately fused to a recently described split M.HhaI enzyme. If correctly designed, such a heterodimeric protein would be active only at the site of assembly. To explore this hypothesis, each domain of split M.HhaI (N- and C-terminal domains) was fused to previously designed 3-finger ZFPs, HS1 and HS2. Our split DNA methylase performed site-specific CpG methylation in living cells without any background methylation when appropriately assembled at the target site. This is the first successful application of the sequence-enable enzyme reassembly approach in vivo.