Book of Abstracts: Albany 2005
Structural Principles of Small RNA Duplex Recognition
The p19 protein from the tombusvirus is a viral suppressor of RNA silencing and has been shown to bind specifically to small interfering RNAs (siRNAs). We have recently determined the 1.85 Å crystal structure of p19 bound to a 21-nucleotide siRNA with a 19 base pair duplex region (1). In the complex, p19 forms a dimer, which has a continuous eight-stranded β-sheet in the center and two α-helical ?arms? protruding from opposite ends. While the RNA duplex is cradled within the saddle-like β-sheet surface, two ?arms? act as a caliper to measure the length of the duplex region, with a tryptophan-pair ?hand? projecting to stack over the terminal RNA base pair on either side. Our structural findings and comparison with another p19-siRNA complex (2) establish principles of the specific RNA selection based on the length of the duplex region and give rise to speculations of how p19 accommodates siRNAs of a range of lengths.
References and Footnotes
Structural Biology Program