从头构建基于组蛋白H3K9me2修饰的合成表观调控通路

构建复杂合成生物体，不仅要在基因组层面实现从头设计合成，还需要在表观基因组层面实现从头设计合成。如何借鉴天然表观调控机制，设计构建合成表观调控通路是实现表观基因组从头设计合成的基础。当前已有研究报道了从头设计构建基于DNA甲基化修饰的表观通路，验证了构建合成表观通路的可行性。但对于具有更复杂调控功能的组蛋白修饰调控通路尚缺乏从头构建的研究。基于此，本项目将在缺乏H3K9me调控通路的酿酒酵母中从头设计构建以H3K9me2/3修饰为核心的表观调控通路，并探索其在表观调控机制研究中的应用。目前我们已经筛选到有功能的H3K9甲基转移酶，成功在酿酒酵母染色质上催化产生了H3K9me2修饰。基于此我们设计了优化H3K9甲基转移酶特异性的筛选系统，并完成了阅读器和读写器元件的设计。本项目旨填补从头构建基于组蛋白修饰的合成表观调控通路的空白，为解析表观遗传调控机制提供新的方法和思路。

The design and construction of complex synthetic organism not only need the ability of de novo design and construction of synthetic genome, but also need the capacity of de novo design and construction of synthetic epigenome. Epigenetic pathways are plastic and inheritable regulatory systems which provide perfect template for designing complex regulatory systems. Thus, the ability to control and engineer epigenetic parts and assembling them into synthetic epigenetic system is vital for construction synthetic epigenome. In previous study, de novo construction of synthetic epigenetic pathway based on DNA m6A modification in mammalian cell line have proven that it is feasible to design and build a synthetic epigenetic pathway. But there are still no reports on de novo construction of synthetic epigenetic system based on histone modifications which play more important roles in regulating gene expression in higher eukaryotes. Based on these, the purpose of this project is to construct synthetic epigenetic parts based on histone H3K9 methylation which is absent in the baker’s yeast, and assemble them into functional synthetic epigenetic regulation pathway. This synthetic epigenetic pathway would further been applied in studying epigenetic regulation mechanisms. So far, we have constructed a H3K9 methyltransferase screening system, using this system, we successfully screened functional H3K9me2 writers in baker’s yeast. We also established validated techniques which would be needed in the following studies in this project. The aim of this project is to establish the design principles for constructing synthetic epigenetic pathways. And providing new ideas and examples for applying the histone modification based synthetic epigenetic pathway in studying epigenetic regulation mechanisms.