siRNAs compete with miRNAs for methylation by HEN1 in Arabidopsis

Authors

Bin Yu, University of Nebraska - LincolnFollow
Liu Bi, University of California - Riverside
Jixian Zhai, University of Delaware
Manu Agarwal, Teri University
Shengben Li, University of California - Riverside
Qingfa Wu, University of California - Riverside
Shou-Wei Ding, University of California - Riverside
Blake C. Meyers, University of DelawareFollow
Hervé Vaucheret, Institut National de la Recherche Agronomique
Xuemei Chen, University of California - RiversideFollow

Date of this Version

2010

Document Type

Article

Citation

Published in Nucleic Acids Research (2010) 38(17): 5844-5850. DOI:10.1093/nar/gkq348

Comments

Copyright © 2010 the Authors. Used by Permission.

Abstract

Plant microRNAs (miRNAs) and small interfering RNAs (siRNAs) bear a 2'-O-methyl group on the 3'-terminal nucleotide. This methyl group is post-synthetically added by the methyltransferase protein HEN1 and protects small RNAs from enzymatic activities that target the 3'-OH. A mutagenesis screen for suppressors of the partial loss-offunction hen1-2 allele in Arabidopsis identified second-site mutations that restore miRNA methylation. These mutations affect two subunits of the DNA-dependent RNA polymerase IV (Pol IV), which is essential for the biogenesis of 24 nt endogenous siRNAs. A mutation in RNA-dependent RNA polymerase 2, another essential gene for the biogenesis of endogenous 24-nt siRNAs, also rescued the defects in miRNA methylation of hen1-2, revealing a previously unsuspected, negative influence of siRNAs on HEN1-mediated miRNA methylation. In addition, our findings imply the existence of a negative modifier of HEN1 activity in the Columbia genetic background.