Recombinant RNA technology: the tRNA scaffold.

RNA has emerged as a major player in most cellular processes. Understanding these processes at the molecular level requires homogeneous RNA samples for structural, biochemical and pharmacological studies. So far, this has been a bottleneck, as the only methods for producing such pure RNA have been in vitro syntheses. Here we describe a generic approach for expressing and purifying structured RNA in Escherichia coli, using tools that parallel those available for recombinant proteins. Our system is based on a camouflage strategy, the 'tRNA scaffold', in which the recombinant RNA is disguised as a natural RNA and thus hijacks the host machinery, escaping cellular RNases. This opens the way to large-scale structural and molecular investigations of RNA function.