Associate Professor Yukihide Tomari, Institute of Molecular and Cellular Biosciences, The University of Tokyo.
Small RNAs guide RNA-induced silencing complexes (RISCs) to regulate their target mRNAs. Argonaute (Ago) proteins bind small RNAs directly, and function as the core component of RISC. RISC assembly follows at least two steps: loading of small RNA duplexes into Ago proteins and unwinding of the two strands within Ago proteins. We and others have previously shown that loading of small RNA duplexes is ATPdriven and requires the Hsc70/Hsp90 chaperone machinery, which generally helps a wide range of client proteins to adopt their active conformation by ATP hydrolysis. It is envisioned that ATP is consumed by the Hsc70/Hsp90 chaperone machinery to open the Ago protein structure so that it can incorporate rigid small RNA duplexes. However the detailed mechanism of this process and the sufficient components for RISC assembly remain unclear. We recently established an in vitro reconstitution system for Drosophila Ago2-RISC assembly composed of Ago2, Dicer-2/R2D2, and five chaperone factors. Our results define the necessary and sufficient components for RISC assembly, providing a biochemical and biophysical framework. I will also introduce our recent efforts to dissect the mechanism by which RISC inhibits protein synthesis in animals and plants.Trade Display by Geneworks in “The Street”, JCSMR from 10am-12noon. Sponsored by the RNA Network of Australasia and GeneWorks. Hosted by Thomas Preiss, Department of Genome Biology, JCSMR and Tony Millar, Plant Sciences Division, Research School of Biology.