Methylation protects miRNAs and siRNAs from a 3′-end uridylation activity in Arabidopsis

Junjie Li, Zhiyong Yang, Bin Yu, Jun Liu, Xuemei Chen

Research output: Contribution to journalArticle

470 Citations (Scopus)

Abstract

Small RNAs of 21-25 nucleotides (nt), including small interfering RNAs (siRNAs) and microRNAs (miRNAs), act as guide RNAs to silence target-gene expression in a sequence-specific manner [1]. In addition to a Dicer homolog, DCL1, the biogenesis of miRNAs in Arabidopsis requires another protein, HEN1 [2, 3]. miRNAs are reduced in abundance and increased in size in hen1 mutants [2, 4-7]. We found that HEN1 is a miRNA methyltransferase that adds a methyl group to the 3′-most nucleotide of miRNAs [8], but the role of miRNA methylation was unknown. Here, we show that siRNAs from sense transgenes, hairpin transgenes, and transposons or repeat sequences, as well as a new class of siRNAs known as trans-acting siRNAs, are also methylated in vivo by HEN1. In addition, we show that the size increase of small RNAs in the hen1-1 mutant is due to the addition of one to five U residues to the 3′ ends of the small RNAs. Therefore, a novel uridylation activity targets the 3′ ends of unmethylated miRNAs and siRNAs in hen1 mutants. We conclude that 3′-end methylation is a common step in miRNA and siRNA metabolism and likely protects the 3′ ends of the small RNAs from the uridylation activity.

Original languageEnglish (US)
Pages (from-to)1501-1507
Number of pages7
JournalCurrent Biology
Volume15
Issue number16
DOIs
StatePublished - Aug 23 2005
Externally publishedYes

Fingerprint

Methylation
small interfering RNA
MicroRNAs
microRNA
Arabidopsis
methylation
Small Interfering RNA
RNA
Transgenes
mutants
transgenes
Nucleotides
Guide RNA
nucleotides
methyltransferases
Methyltransferases
Metabolism
Gene expression
transposons
Gene Expression

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Methylation protects miRNAs and siRNAs from a 3′-end uridylation activity in Arabidopsis. / Li, Junjie; Yang, Zhiyong; Yu, Bin; Liu, Jun; Chen, Xuemei.

In: Current Biology, Vol. 15, No. 16, 23.08.2005, p. 1501-1507.

Research output: Contribution to journalArticle

Li, Junjie ; Yang, Zhiyong ; Yu, Bin ; Liu, Jun ; Chen, Xuemei. / Methylation protects miRNAs and siRNAs from a 3′-end uridylation activity in Arabidopsis. In: Current Biology. 2005 ; Vol. 15, No. 16. pp. 1501-1507.
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