An effector of RNA-directed DNA methylation in arabidopsis is an ARGONAUTE 4- and RNA-binding protein.
DNA methylation is a conserved epigenetic mark in plants and mammals. In Arabidopsis, DNA methylation can be triggered by small interfering RNAs (siRNAs) through an RNA-directed DNA methylation (RdDM) pathway. Here, we report the identification of an RdDM effector, KTF1. Loss-of-function mutations in KTF1 reduce DNA methylation and release the silencing of RdDM target loci without abolishing the siRNA triggers. KTF1 has similarity to the transcription elongation factor SPT5 and contains a C-terminal extension rich in GW/WG repeats. KTF1 colocalizes with ARGONAUTE 4 (AGO4) in punctate nuclear foci and binds AGO4 and RNA transcripts. Our results suggest KTF1 as an adaptor protein that binds scaffold transcripts generated by Pol V and recruits AGO4 and AGO4-bound siRNAs to form an RdDM effector complex. The dual interaction of an effector protein with AGO and small RNA target transcripts may be a general feature of RNA-silencing effector complexes.
Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, 92521, USA.
Xin-Jian
XJ
He
Yi-Feng
YF
Hsu
Shihua
S
Zhu
Andrzej T
AT
Wierzbicki
Olga
O
Pontes
Craig S
CS
Pikaard
Hai-Liang
HL
Liu
Co-Shine
CS
Wang
Hailing
H
Jin
Jian-Kang
JK
Zhu
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D060565:Argonaute Proteins; D001665:Binding Sites; D019175:DNA Methylation; D018744:DNA, Plant / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D034622:RNA Interference; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
C471209:AGO4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D018744:DNA, Plant; C542552:KTF1 protein, Arabidopsis; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C471271:ROS1 protein, Arabidopsis; D014157:Transcription Factors; C538841:RNA polymerase V, Arabidopsis; D012321:DNA-Directed RNA Polymerases