FIGURE 1.

The one-step and two-step strategies for synthesis of lariat RNA. (A) One-step lariat RNA synthesis using a deoxyribozyme to mediate attack of an internal 2′-hydroxyl group on the 5′-triphosphate of the same RNA substrate strand. (B) Two-step lariat RNA synthesis, in which a deoxyribozyme first synthesizes 2′,5′-branched RNA and the loop is then closed using T4 RNA ligase. In the first step, L and R denote the left-hand and right-hand RNA substrates. The inset shows the optimal stem-loop structure near the ligation site during loop closure (see text).