Unique functionality of 22-nt miRNAs in triggering RDR6-dependent siRNA biogenesis from target transcripts in Arabidopsis

Josh T. Cuperus, Alberto Carbonell, Noah Fahlgren, Hernan Garcia-Ruiz, Russell T. Burke, Atsushi Takeda, Christopher M. Sullivan, Sunny D. Gilbert, Taiowa A. Montgomery, James C. Carrington

Research output: Contribution to journalArticle

252 Scopus citations

Abstract

RNA interference pathways can involve amplification of secondary siRNAs by RNA-dependent RNA polymerases. In plants, RDR6-dependent secondary siRNAs arise from transcripts targeted by some microRNAs (miRNAs). Here, Arabidopsis thaliana secondary siRNAs from mRNA as well as trans-acting siRNAs are shown to be triggered through initial targeting by a 22-nucleotide (nt) miRNA that associates with AGO1. In contrast to canonical 21-nt miRNAs, 22-nt miRNAs primarily arise from foldback precursors containing asymmetric bulges. Using artificial miRNA constructs, conversion of asymmetric foldbacks to symmetric foldbacks resulted in the production of 21-nt forms of miR173, miR472 and miR828. Both 21-and 22-nt forms associated with AGO1 and guided accurate slicer activity, but only 22-nt forms were competent to trigger RDR6-dependent siRNA production from target RNA. These data suggest that AGO1 functions differentially with 21-and 22-nt miRNAs to engage the RDR6-associated amplification apparatus.

Original languageEnglish (US)
Pages (from-to)997-1003
Number of pages7
JournalNature Structural and Molecular Biology
Volume17
Issue number8
DOIs
StatePublished - Aug 1 2010

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ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

Cite this

Cuperus, J. T., Carbonell, A., Fahlgren, N., Garcia-Ruiz, H., Burke, R. T., Takeda, A., Sullivan, C. M., Gilbert, S. D., Montgomery, T. A., & Carrington, J. C. (2010). Unique functionality of 22-nt miRNAs in triggering RDR6-dependent siRNA biogenesis from target transcripts in Arabidopsis. Nature Structural and Molecular Biology, 17(8), 997-1003. https://doi.org/10.1038/nsmb.1866