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Specific but interdependent functions for A rabidopsis AGO 4 and AGO 6 in RNA ‐directed DNA methylation
Author(s) -
Duan ChengGuo,
Zhang Huiming,
Tang Kai,
Zhu Xiaohong,
Qian Weiqiang,
Hou YuehJu,
Wang Bangshing,
Lang Zhaobo,
Zhao Yang,
Wang Xingang,
Wang Pengcheng,
Zhou Jianping,
Liang Gaimei,
Liu Na,
Wang Chunguo,
Zhu JianKang
Publication year - 2014
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.201489453
Subject(s) - biology , dna methylation , rna , dna , methylation , microbiology and biotechnology , genetics , gene expression , gene
Argonaute ( AGO ) family proteins are conserved key components of small RNA ‐induced silencing pathways. In the RNA ‐directed DNA methylation ( R d DM ) pathway in Arabidopsis , AGO 6 is generally considered to be redundant with AGO 4. In this report, our comprehensive, genomewide analyses of AGO 4‐ and AGO 6‐dependent DNA methylation revealed that redundancy is unexpectedly negligible in the genetic interactions between AGO 4 and AGO 6. Immunofluorescence revealed that AGO 4 and AGO 6 differ in their subnuclear co‐localization with RNA polymerases required for R d DM . Pol II and AGO 6 are absent from perinucleolar foci, where Pol V and AGO 4 are co‐localized. In the nucleoplasm, AGO 4 displays a strong co‐localization with Pol II, whereas AGO 6 co‐localizes with Pol V. These patterns suggest that R d DM is mediated by distinct, spatially regulated combinations of AGO proteins and RNA polymerases. Consistently, Pol II physically interacts with AGO 4 but not AGO 6, and the levels of Pol V‐dependent scaffold RNA s and Pol V chromatin occupancy are strongly correlated with AGO 6 but not AGO 4. Our results suggest that AGO 4 and AGO 6 mainly act sequentially in mediating small RNA ‐directed DNA methylation.