Download MendeleyStructural insights into RISC assembly facilitated by dsRNA-binding domains of human RNA helicase A (DHX9).
Fu, Q., Yuan, Y.A.(2013) Nucleic Acids Res 41: 3457-3470
- PubMed: 23361462
- DOI: https://doi.org/10.1093/nar/gkt042
- Primary Citation of Related Structures:
3VYX, 3VYY - PubMed Abstract:
Intensive research interest has focused on small RNA-processing machinery and the RNA-induced silencing complex (RISC), key cellular machines in RNAi pathways. However, the structural mechanism regarding RISC assembly, the primary step linking small RNA processing and RNA-mediated gene silencing, is largely unknown. Human RNA helicase A (DHX9) was reported to function as an RISC-loading factor, and such function is mediated mainly by its dsRNA-binding domains (dsRBDs). Here, we report the crystal structures of human RNA helicase A (RHA) dsRBD1 and dsRBD2 domains in complex with dsRNAs, respectively. Structural analysis not only reveals higher siRNA duplex-binding affinity displayed by dsRBD1, but also identifies a crystallographic dsRBD1 pair of physiological significance in cooperatively recognizing dsRNAs. Structural observations are further validated by isothermal titration calorimetric (ITC) assay. Moreover, co-immunoprecipitation (co-IP) assay coupled with mutagenesis demonstrated that both dsRBDs are required for RISC association, and such association is mediated by dsRNA. Hence, our structural and functional efforts have revealed a potential working model for siRNA recognition by RHA tandem dsRBDs, and together they provide direct structural insights into RISC assembly facilitated by RHA.
Organizational Affiliation:
Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.
