Histone H1 prevents non-CG methylation-mediated small RNA biogenesis in Arabidopsis heterochromatin

eLife

David B Lyons¹  Jaemyung Choi¹  Daniel Zilberman² 

[1] Department of Cell and Developmental Biology, John Innes Centre, Norwich, United Kingdom;Department of Cell and Developmental Biology, John Innes Centre, Norwich, United Kingdom;Institute of Science and Technology, Klosterneuburg, Austria;

关键词: DNA methylation;    small RNA;    histone H1;    A. thaliana;   

DOI  :  10.7554/eLife.72676

来源: eLife Sciences Publications, Ltd

【 摘 要 】

Flowering plants utilize small RNA (sRNA) molecules to guide DNA methyltransferases to genomic sequences. This RNA-directed DNA methylation (RdDM) pathway preferentially targets euchromatic transposable elements. However, RdDM is thought to be recruited by methylation of histone H3 at lysine 9 (H3K9me), a hallmark of heterochromatin. How RdDM is targeted to euchromatin despite an affinity for H3K9me is unclear. Here, we show that loss of histone H1 enhances heterochromatic RdDM, preferentially at nucleosome linker DNA. Surprisingly, this does not require SHH1, the RdDM component that binds H3K9me. Furthermore, H3K9me is dispensable for RdDM, as is CG DNA methylation. Instead, we find that non-CG methylation is specifically associated with sRNA biogenesis, and without H1 sRNA production quantitatively expands to non-CG-methylated loci. Our results demonstrate that H1 enforces the separation of euchromatic and heterochromatic DNA methylation pathways by excluding the sRNA-generating branch of RdDM from non-CG-methylated heterochromatin.

【 授权许可】

CC BY