A One Precursor One siRNA Model for Pol IV-Dependent siRNA Biogenesis.
Cell
; 163(2): 445-55, 2015 Oct 08.
Article
in En
| MEDLINE
| ID: mdl-26451488
ABSTRACT
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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Arabidopsis
/
RNA, Plant
/
RNA, Small Interfering
Language:
En
Journal:
Cell
Year:
2015
Type:
Article
Affiliation country:
United States