水稻NERD途径关键基因OsNERD1的功能研究  

The Function of a OsNERD1 Gene in NERD Pathway of Oryza sativa

作　　者：陈雄平 

机构地区：[1]华中农业大学作物遗传改良重点实验室,武汉430070

出　　处：《湖北农业科学》2015年第4期988-992,1006,共6页Hubei Agricultural Sciences

摘　　要：Rd DM(RNA-directed DNA methylation)是一种存在于植物中转录水平的基因沉默(Transcriptional gene silencing,TGS)机制,需要DCL3、RDR2及AGO4/6等多种蛋白介导si RNA同源位点的甲基化。拟南芥中发现了独立于Rd DM的一条新TGS途径,其关键蛋白为At NERD1。At NERD1能够与AGO2蛋白相互作用,产生21nt的s RNAs分子,介导某些新近进化基因的甲基化,并影响其组蛋白修饰。序列同源比对结果表明,水稻中存在有与At NERD同源非常高的蛋白,分别命名为Os NERD1和Os NERD2。体外结合试验结果表明,Os NERD的PHD结构域能够结合H3K4me3,Os NERD1参与下游基因的表观调控。对OsNERD突变体中一些转座子的检测表明,该基因的突变会影响转座子的表达量变化及其表观修饰,并且这些转座子集中在gypsy家族,gypsy家族转座子在营养核中表达活跃,可能与Os NERD1的花粉不育相关。RNA-directed DNA methylation （RdDM） is a transcriptional gene silencing （TGS） pathway existed widely in plant. DCL3, RDR2 and AGO4/6 are involved in RdDM and regulate the methylation of homology locus. A new pathway independent of RdDM is found recently in Arabidopsis and the key protein involved is named AtNERD1. AtNERD1 interacts with AGO2 and affects the methylation and histone modification of the newly evoluted pseudogenes and produces 21 nt sRNAs. Sequence homology analyses showed that rice had two proteins highly homologous to AtNERD1 named OsNERD1 and OsNERD2. The binding capacity to H3K4me3 was proved with in vitro binding assay. Among the OsNERD1 mutants, the expression of transposons was notably changed, indicating that OsNERD1 may be involved in the epigenetic regulation of transposable elements. Most of these diverse transposons are belonged to the Ty3/gypsy family with highly expressed in vegetative nucleus. The phenotype of OsNERDI may be caused by the highly expressed gypsy family transposons.

关 键 词：NERD SRNA RDDM 转座子 DNA甲基化 

分 类 号：S511[农业科学—作物学] Q74[生物学—分子生物学]