Structure of C3PO and mechanism of human RISC activation

Xuecheng Ye, Nian Huang, Ying Liu, Zain Paroo, Carlos Huerta, Peng Li, She Chen, Qinghua Liu, Hong Zhang

Research output: Contribution to journalArticle

98 Scopus citations

Abstract

Assembly of the RNA-induced silencing complex (RISC) consists of loading duplex (guide-passenger) siRNA onto Argonaute (Ago2) and removing the passenger strand. Ago2 contributes critically to RISC activation by nicking the passenger strand. Here we reconstituted duplex siRNA-initiated RISC activity using recombinant human Ago2 (hAgo2) and C3PO, indicating that C3PO has a critical role in hAgo2-RISC activation. Consistently, genetic depletion of C3PO compromised RNA silencing in mammalian cells. We determined the crystal structure of hC3PO, which reveals an asymmetric octamer barrel consisting of six translin and two TRAX subunits. This asymmetric assembly is critical for the function of C3PO as an endonuclease that cleaves RNA at the interior surface. The current work supports a Dicer-independent mechanism for human RISC activation, in which Ago2 directly binds duplex siRNA and nicks the passenger strand, and then C3PO activates RISC by degrading the Ago2-nicked passenger strand.

Original languageEnglish (US)
Pages (from-to)650-657
Number of pages8
JournalNature Structural and Molecular Biology
Volume18
Issue number6
DOIs
StatePublished - Jun 2011

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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    Ye, X., Huang, N., Liu, Y., Paroo, Z., Huerta, C., Li, P., Chen, S., Liu, Q., & Zhang, H. (2011). Structure of C3PO and mechanism of human RISC activation. Nature Structural and Molecular Biology, 18(6), 650-657. https://doi.org/10.1038/nsmb.2032