siRNAs compete with miRNAs for methylation by HEN1 in Arabidopsis

Bin Yu, Liu Bi, Jixian Zhai, Manu Agarwal, Shengben Li, Qingfa Wu, Shou Wei Ding, Blake C. Meyers, Hervé Vaucheret, Xuemei Chen

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


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-of-function 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.

Original languageEnglish (US)
Article numbergkq348
Pages (from-to)5844-5850
Number of pages7
JournalNucleic acids research
Issue number17
StatePublished - May 6 2010
Externally publishedYes

ASJC Scopus subject areas

  • Genetics


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