In vitro selection of a 5'-purine nucleotide transferase ribozyme.

Here we report a ribozyme that catalyzes the 5'-nucleotidyl transfer reaction forming the 2'-5' phosphodiester bond. This ribozyme was retrieved as a sole sequence in the pool enriched for the 5'-triphosphate-dependent activities in incorporating ATP-gammaS. The originally selected ribozyme consisting of 109-nucleotide was miniaturized to 45-nucleotide M4 ribozyme via mutation studies, and based on this mini-ribozyme a trans-acting system was constructed. Interestingly, M4 ribozyme promiscuously accepts a variety of purine nucleotides. This remarkable ability of M4 ribozyme would lead us to the development of a new tool for the 5'-modification of RNAs with unique chemical groups.