拟南芥中Dicer家族蛋白切割产生小RNA的结构生物学研究

小RNA在表观遗传调控中起着广泛而关键的作用。小RNA的生物合成由具备“分子尺”功能的Dicer家族核酸内切酶直接决定。尽管前期的研究已从不同程度上揭示了不同物种中Dicer产生小RNA的机理，但是这些机理之间的关联和差异并不十分清楚，从大程度上限制了我们对Dicer切割产生小RNA原理共性和特性的了解。我们拟以拟南芥中Dicer家族蛋白为研究对象，在DCL1和DCL3切割机制研究的基础上，利用冷冻电镜技术，基于结构生物学开展对DCL2和DCL4的蛋白质与相应互作蛋白及底物RNA复合物结构和功能的研究，综合运用生物化学、植物分子遗传学等手段揭示DCL2、DCL4产生22-nt siRNA、21-nt siRNA分子机制，通过总结拟南芥中Dicer家族蛋白DCL1、DCL2、DCL3、DCL4产生不同RNA的一般规律和特性，深化对表观遗传系统的认知，为小RNA的人工设计提供潜在的理论依据。

Small RNAs (sRNAs) plays a critical role to affect the epigenetic regulation. Dicer, which function as “molecular ruler”, decide the production of biosynthesis for small RNAs specifically. Although the mechanism for Dicer producing sRNAs have been revealed in different species, the correlation and differences between these mechanisms are not clear, which greatly limits our understanding for the commonality and characteristics of Dicer's cleavage mechanism to produce small RNA. On the basis of DCL1 and DCL3 cutting mechanism research, we intend to study the Dicer family protein in Arabidopsis. we plan to reveal the structure and function of DCL2 and DCL4 proteins with corresponding interacting proteins and substrate RNA complexes by combining structural, biochemical and plant molecular genetics studies, to describe the molecular mechanism of 22-nt siRNA and 21-nt siRNA production. Finally, the general rules and characteristics of different RNAs produced by the Dicer family proteins will be summarized by analysis for the dicing mechanism of DCL1, DCL2, DCL3 and DCL4 in Arabidopsis, the understanding of epigenetic system is deepened thereby, and a potential theoretical basis may be provided for the artificial design of small RNA.