Open AccessA One Precursor One siRNA Model for Pol IV-Dependent siRNA Biogenesis
Author(s) -
Jixian Zhai,
Sylvain Bischof,
Haifeng Wang,
Suhua Feng,
Tzuufen Lee,
Chong Teng,
Xinyuan Chen,
Soo Young Park,
Linshan Liu,
Javier GallegoBartolomé,
Wanlu Liu,
Ian R. Henderson,
Blake C. Meyers,
Israel Ausín,
Steven E. Jacobsen
Publication year - 2015
Publication title -
cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 26.304
H-Index - 776
eISSN - 1097-4172
pISSN - 0092-8674
DOI - 10.1016/j.cell.2015.09.032
Subject(s) - biology , small interfering rna , trans acting sirna , dna methylation , transcription (linguistics) , microbiology and biotechnology , rna , genetics , gene , gene expression , linguistics , philosophy
RNA-directed DNA methylation in Arabidopsis thaliana is driven by the plant-specific RNA Polymerase IV (Pol IV). It has been assumed that a Pol IV transcript can give rise to multiple 24-nt small interfering RNAs (siRNAs) that target DNA methylation. Here, we demonstrate that Pol IV-dependent RNAs (P4RNAs) from wild-type Arabidopsis are surprisingly short in length (30 to 40 nt) and mirror 24-nt siRNAs in distribution, abundance, strand bias, and 5'-adenine preference. P4RNAs exhibit transcription start sites similar to Pol II products and are featured with 5'-monophosphates and 3'-misincorporated nucleotides. The 3'-misincorporation preferentially occurs at methylated cytosines on the template DNA strand, suggesting a co-transcriptional feedback to siRNA biogenesis by DNA methylation to reinforce silencing locally. These results highlight an unusual mechanism of Pol IV transcription and suggest a "one precursor, one siRNA" model for the biogenesis of 24-nt siRNAs in Arabidopsis.
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