Structure of C3PO and mechanism of human RISC activation

Journal Article · Fri Aug 26 04:00:00 EDT 2011 · Nat. Struct. Mol. Biol.

DOI:https://doi.org/10.1038/nsmb.2032· OSTI ID:1020588

Ye, Xuecheng; Huang, Nian; Liu, Ying; Paroo, Zain; Huerta, Carlos; Li, Peng; Chen, She; Liu, Qinghua; Zhang, Hong ^[1]

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1. NIBS-China

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.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: OTHERNIH
• OSTI ID: 1020588
• Journal Information: Nat. Struct. Mol. Biol., Journal Name: Nat. Struct. Mol. Biol. Journal Issue: (6) ; 06, 2011 Vol. 18; ISSN 1545-9993
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
CRYSTAL STRUCTURE
ENDONUCLEASES
GENETICS
OCCUPANTS
RNA