Figure 2. Association kinetics of Bst S4.

(a) Representative gel mobility shift of 5’ domain RNA. Excess S4 was added at 42°C and aliquots loaded directly onto a native polyacrylamide gel at specific time intervals. The gel was run continuously during the experiment. (b) ³²P-labeled 5’ domain (open circles, dashed line) or 5WJ (closed circles, solid line) were prefolded in HKM4 buffer 20 min at 42°C before S4 was added. The fraction of bound RNA was fit to f_B = f_max(1 − exp(−k_obst)); k_obs was 7 ± 2 min⁻¹ (5WJ) and 6 ± 1 min⁻¹ (5’ dom).