FIGURE 8.

RNA-IN:RNA-OUT pairing reactions. (A) ³²P-labeled RNA-IN-160 (0.85 nM) was mixed with excess ³²P-labeled RNA-OUT (8.5 nM) and, where indicated, untagged WT or K56A Hfq (45 nM). Note that RNA-OUT had a lower specific activity than RNA-IN. At the indicated time points, pairing reactions were stopped by treatment with a phenol/water mix and immediately loaded onto a 6% native polyacrylamide gel. (B) The amount of RNA-OUT:RNA-IN* complex (OUT:IN*) was determined as a percentage of total RNA-IN* for each time point and plotted as a function of time. Error bars represent the standard error from three experiments. The observed rate constant (k_obs) is indicated for each reaction. These values were derived from curves corresponding to the equation describing the rate of exponential association, presented in Materials and Methods.