甲基转移酶
甲基化
表观遗传学
组蛋白甲基转移酶
生物
DNA甲基化
组蛋白甲基化
RNA导向的DNA甲基化
RNA甲基化
表观遗传学
组蛋白
体育锻炼的表观遗传学
遗传学
细胞生物学
DNA
基因
基因表达
作者
Hume Stroud,J. Truman,Jiamu Du,Xuehua Zhong,Suhua Feng,Lianna M. Johnson,Dinshaw J. Patel,Steven E. Jacobsen
摘要
Non-CG methylation is abundant in plants, but its functions are poorly understood. A new study has uncovered the contributions of each non-CG methyltransferase, including the poorly characterized methyltransferase CMT2, to DNA methylation patterning and gene silencing. The results suggest that non-CG methyltransferases participate in self-reinforcing loop mechanisms with histone H3 K9 methylation and small RNAs to control gene silencing throughout the Arabidopsis genome. DNA methylation occurs in CG and non-CG sequence contexts. Non-CG methylation is abundant in plants and is mediated by CHROMOMETHYLASE (CMT) and DOMAINS REARRANGED METHYLTRANSFERASE (DRM) proteins; however, its roles remain poorly understood. Here we characterize the roles of non-CG methylation in Arabidopsis thaliana. We show that a poorly characterized methyltransferase, CMT2, is a functional methyltransferase in vitro and in vivo. CMT2 preferentially binds histone H3 Lys9 (H3K9) dimethylation and methylates non-CG cytosines that are regulated by H3K9 methylation. We revealed the contributions and redundancies between each non-CG methyltransferase in DNA methylation patterning and in regulating transcription. We also demonstrate extensive dependencies of small-RNA accumulation and H3K9 methylation patterning on non-CG methylation, suggesting self-reinforcing mechanisms between these epigenetic factors. The results suggest that non-CG methylation patterns are critical in shaping the landscapes of histone modification and small noncoding RNA.
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