Fig. 1. Effects of “nick-like structure” on RNA cyclization by Rnl2. (A) RNA substrate L-22a having “nick-like structure” (the top) and the relevant structures, which are same as the secondary structures simulated by Mfold software (Fig. S1†). (B) Time-courses for the intramolecular cyclization of L-22a (red circles), L-22b (purple rectangles), L-22c (blue upright triangles) and L-22d (black inverted triangles) in (A). [RNA] = 1 μM and [Rnl2] = 0.4 U μL⁻¹ in 1× buffer at 25 °C. The corresponding 12% denaturing PAGE analyses are presented in (C), except for L-22d (Fig. S2†). L-22 and C-22 refer to 22-nt linear RNA and 22-nt circular RNA, respectively. (D) Time-course for the intramolecular cyclization of L-22a with 0.04 U μL⁻¹ of Rnl2 (the PAGE pattern is shown in Fig. S3†).