A micrococcal nuclease homologue in RNAi effector complexes

Amy A. Caudy, René F. Ketting, Scott M. Hammond, Ahmet M. Denli, Anja M.P. Bathoorn, Bastiaan B.J. Tops, Jose M. Silva, Mike M. Myers, Gregory J. Hannon, Ronald H.A. Plasterk

Research output: Contribution to journalArticlepeer-review

359 Citations (Scopus)


RNA interference (RNAi) regulates gene expression by the cleavage of messenger RNA, by mRNA degradation and by preventing protein synthesis. These effects are mediated by a ribonucleo-protein complex known as RISC (RNA-induced silencing complex. We have previously identified four Drosophila components (short interfering RNAs, Argonaute 2 (ref. 2), VIG and FXR of a RISC enzyme that degrades specific mRNAs in response to a double-stranded-RNA trigger. Here we show that Tudor-SN (tudor staphylococcal nuclease) - a protein containing five staphylococcal/micrococcal nuclease domains and a tudor domain - is a component of the RISC enzyme in Caenorhabditis elegans, Drosophila and mammals. Although Tudor-SN contains non-canonical active-site sequences, we show that purified Tudor-SN exhibits nuclease activity similar to that of other staphylococcal nucleases. Notably, both purified Tudor-SN and RISC are inhibited by a specific competitive inhibitor of micrococcal nuclease. Tudor-SN is the first RISC subunit to be identified that contains a recognizable nuclease domain, and could therefore contribute to the RNA degradation observed in RNAi.

Original languageEnglish
Pages (from-to)411-414
Number of pages4
Issue number6956
Publication statusPublished - 25 Sept 2003
Externally publishedYes


  • Animals
  • Binding Sites
  • Caenorhabditis elegans/enzymology
  • Drosophila melanogaster/enzymology
  • Macromolecular Substances
  • Micrococcal Nuclease/chemistry
  • Protein Structure, Tertiary
  • RNA Interference
  • RNA Processing, Post-Transcriptional
  • RNA-Induced Silencing Complex/chemistry


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