Deoxyribozymes that synthesize branched and lariat RNA

Branched RNA molecules with a 2',5'-phosphodiester linkage are important biochemical intermediates. Lariat RNA is a particular type of branched RNA that is formed during intron splicing in vivo. Synthesis of branched and lariat RNA is challenging, and there are few general approaches that are applicable in vitro. Here we report the identification of divalent metal-dependent deoxyribozymes (DNA enzymes) that synthesize branched and lariat RNA. In vitro selection was used to obtain deoxyribozymes that selectively join an internal RNA 2'-hydroxyl with a 5'-terminal triphosphate in a convenient "binding arms" format. At least 85% yield of 2',5'-branched RNA is obtained at 37 degrees C and 20 mM Mn2+, pH 7.5 in