dsRNA Binding Properties of RDE-4 and TRBP Reflect Their Distinct Roles in RNAi

作者：Parker Greg S; Maity Tuhin Subhra; Bass Brenda L^*

来源：Journal of Molecular Biology, 2008, 384(4): 967-979.

DOI：10.1016/j.jmb.2008.10.002

• cooperativity
• RNA interference
• Dicer
• C. elegans
• siRNA

Double-stranded RNA (dsRNA)-binding proteins facilitate Dicer functions in RNA interference. Caenorhabditis elegans RDE-4 facilitates cleavage of long dsRNA to small interfering RNA (siRNA), while human trans-activation response RNA-binding protein (TRBP) functions downstream to pass siRNA to the RNA-induced silencing complex. We show that these distinct in vivo roles are reflected in in vitro binding properties. RDE-4 preferentially binds long dsRNA, while TRBP binds siRNA with an affinity that is independent of dsRNA length. These properties are mechanistically based on the fact that RDE-4 binds cooperatively, via contributions from multiple domains, while TRBP binds noncooperatively. Our studies offer a paradigm for how dsRNA-binding proteins, which are not sequence specific, discern dsRNA length. Additionally, analyses of the ability of RDE-4 deletion constructs and RDE-4/TRBP chimeras to reconstitute Dicer activity suggest RDE-4 promotes activity using its dSRNA-binding motif 2 to bind dsRNA, its linker region to interact with Dicer, and its C-terminus for Dicer activation.

• 出版日期2008-12-26