Dicer's Helicase Domain Discriminates dsRNA Termini to Promote an Altered Reaction Mode

Noah C. Welker, Tuhin S. Maity, Xuecheng Ye, P. Joseph Aruscavage, Ammie A. Krauchuk, Qinghua Liu, Brenda L. Bass

Research output: Contribution to journalArticlepeer-review

101 Scopus citations


The role of Dicer's helicase domain is enigmatic, but in vivo it is required for processing certain endogenous siRNA, but not miRNA. By using Caenorhabditis elegans extracts or purified Drosophila Dicer-2 we compared activities of wild-type enzymes and those containing mutations in the helicase domain. We found the helicase domain was essential for cleaving dsRNA with blunt or 5'-overhanging termini, but not those with 3' overhangs, as found on miRNA precursors. Further, blunt termini, but not 3' overhangs, led to increased siRNAs from internal regions of dsRNA; this activity required ATP and a functional helicase domain. Our data suggest that blunt or 5'-overhanging termini engage Dicer's helicase domain to facilitate accumulation of siRNAs from internal regions of a dsRNA, an activity suited for processing long siRNA precursors of low abundance, but not necessary for the single cleavage required for miRNA processing.

Original languageEnglish (US)
Pages (from-to)589-599
Number of pages11
JournalMolecular cell
Issue number5
StatePublished - Mar 4 2011

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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