Identification of Pol IV and RDR2-dependent precursors of 24 nt siRNAs guiding de novo DNA methylation in Arabidopsis

eLife

Ram Podicheti¹  Haixu Tang²  Vibhor Mishra²  Jing Wang³  Michelle Marasco⁴  Craig S Pikaard⁵  Doug Rusch⁵  Todd Blevins⁶ 

[1] Department of Biology, Indiana University, Bloomington, United States;Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, United States;School of Informatics and Computing, Indiana University, Bloomington, United States;Center for Genomics and Bioinformatics, Indiana University, Bloomington, United States;Department of Biology, Indiana University, Bloomington, United States;Howard Hughes Medical Institute, Indiana University, Bloomington, United States;

关键词: RNA silencing;    epigenetic;    RNA-directed DNA methylation;    noncoding RNA;    RNA interference;    transcription;   

DOI  :  10.7554/eLife.09591

来源: DOAJ

【 摘 要 】

In Arabidopsis thaliana, abundant 24 nucleotide small interfering RNAs (24 nt siRNA) guide the cytosine methylation and silencing of transposons and a subset of genes. 24 nt siRNA biogenesis requires nuclear RNA polymerase IV (Pol IV), RNA-dependent RNA polymerase 2 (RDR2) and DICER-like 3 (DCL3). However, siRNA precursors are mostly undefined. We identified Pol IV and RDR2-dependent RNAs (P4R2 RNAs) that accumulate in dcl3 mutants and are diced into 24 nt RNAs by DCL3 in vitro. P4R2 RNAs are mostly 26-45 nt and initiate with a purine adjacent to a pyrimidine, characteristics shared by Pol IV transcripts generated in vitro. RDR2 terminal transferase activity, also demonstrated in vitro, may account for occasional non-templated nucleotides at P4R2 RNA 3’ termini. The 24 nt siRNAs primarily correspond to the 5’ or 3’ ends of P4R2 RNAs, suggesting a model whereby siRNAs are generated from either end of P4R2 duplexes by single dicing events.

【 授权许可】

Unknown