QIP, a putative exonuclease, interacts with the Neurospora Argonaute protein and facilitates conversion of duplex siRNA into single strands

Mekhala Maiti, Heng Chi Lee, Yi Liu

Research output: Contribution to journalArticle

89 Citations (Scopus)

Abstract

Single-stranded small interfering RNA (siRNA) guides the cleavage of homologous mRNA by Argonaute proteins, the catalytic core of the RNA-induced silencing complex (RISC), in the conserved RNA interference (RNAi) pathway. The separation of the siRNA duplex into single strands is essential for the activation of RISC. Previous biochemical studies have suggested that Argonaute proteins cleave and remove the passenger strand of siRNA duplex from RISC, but the in vivo importance of this process and the mechanism for the removal of the nicked passenger strand are not known. Here, we show that in the filamentous fungus Neurospora, the Argonaute homolog QDE-2 and its slicer function are required for the generation of single-stranded siRNA and gene silencing in vivo. Biochemical purification of QDE-2 led to the identification of QIP, a QDE-2-interacting protein, with an exonuclease domain. The disruption of qip in Neurospora impaired gene silencing and siRNA accumulated, mostly in nicked duplex form. Furthermore, our results suggest that QIP acts as an exonuclease that cleaves and removes the nicked passenger strand from siRNA duplex in a QDE-2-dependent manner. Together, these results suggest that both the cleavage and removal of the passenger strand from the siRNA duplex are important steps in RNAi pathways.

Original languageEnglish (US)
Pages (from-to)590-600
Number of pages11
JournalGenes and Development
Volume21
Issue number5
DOIs
StatePublished - Mar 1 2007

Fingerprint

Argonaute Proteins
Neurospora
Exonucleases
Small Interfering RNA
RNA-Induced Silencing Complex
RNA Interference
Gene Silencing
RNA Cleavage
Catalytic RNA
Catalytic Domain
Fungi
Messenger RNA

Keywords

  • Argonaute
  • Exonuclease
  • Neurospora
  • RISC
  • RNAi
  • siRNA

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology

Cite this

QIP, a putative exonuclease, interacts with the Neurospora Argonaute protein and facilitates conversion of duplex siRNA into single strands. / Maiti, Mekhala; Lee, Heng Chi; Liu, Yi.

In: Genes and Development, Vol. 21, No. 5, 01.03.2007, p. 590-600.

Research output: Contribution to journalArticle

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