RNA polymerase V transcription guides ARGONAUTE4 to chromatin.
Retrotransposons and repetitive DNA elements in eukaryotes are silenced by small RNA-directed heterochromatin formation. In Arabidopsis, this process involves 24-nt siRNAs that bind to ARGONAUTE4 (AGO4) and facilitate the targeting of complementary loci via unknown mechanisms. Nuclear RNA polymerase V (Pol V) is an RNA silencing enzyme recently shown to generate noncoding transcripts at loci silenced by 24-nt siRNAs. We show that AGO4 physically interacts with these Pol V transcripts and is thereby recruited to the corresponding chromatin. We further show that DEFECTIVE IN MERISTEM SILENCING3 (DMS3), a structural maintenance of chromosomes (SMC) hinge-domain protein, functions in the assembly of Pol V transcription initiation or elongation complexes. Collectively, our data suggest that AGO4 is guided to target loci through base-pairing of associated siRNAs with nascent Pol V transcripts.
Biology Department, Washington University, St. Louis, Missouri, USA.
Andrzej T
AT
Wierzbicki
Thomas S
TS
Ream
Jeremy R
JR
Haag
Craig S
CS
Pikaard
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060565:Argonaute Proteins; D002843:Chromatin / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D008954:Models, Biological; D034741:RNA, Small Interfering / Q000378:metabolism; D014158:Transcription, Genetic
C471209:AGO4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; C529025:DMS3 protein, Arabidopsis; D034741:RNA, Small Interfering; C538841:RNA polymerase V, Arabidopsis; D012321:DNA-Directed RNA Polymerases