Caged RNA: photo-control of a ribozyme reaction.

We report here the first photo-chemical control of a ribozyme reaction by the site-specific modification of the 2'-hydroxyl nucleophile in the hammerhead system with a caging functionality. Rapid laser photolysis of the O-(2-nitrobenzyl) caging group initiates an efficient and accurate hammerhead-catalyzed cleavage of substrate RNA under native conditions. RNAs in which reactive functionalities or recognition elements are caged in this manner will be useful tools to probe RNA reactivity and dynamics.