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. 2015 Oct 22;43(21):10421–10429. doi: 10.1093/nar/gkv1098

Figure 2.

Figure 2.

Force dependence of the probability of entering into a backtracked state for P2 RdRp. (A) Probability density distributions for P2 RdRp transcriptional activity acquired at 16 pN (dark blue, 102 traces), 20 pN (light blue, 184 traces), 25 pN (green, 200 traces), 30 pN (yellow, 210 traces) and 35 pN (red, 76 traces). The error bars correspond to one standard deviation estimated from 1000 bootstraps. (B) A zoom-in of (A) for dwell-times longer than 10 s. (C) Probability that a dwell-time exceeds 20 s as a function of the applied force. The error bars are the standard deviation of the distribution extracted from 1000 bootstraps. (D) Proposed model that accounts for the force-dependence of the probability of finding P2 RdRp in a backtracked state. At low force (small distance between single nucleotides on the non-template strand), the tension at the dsRNA fork is small enough to allow the rehybridization of the template strand to the non-template strand, compensating the melting of the dsRNA product, leading to the backtracking of the RdRp. At high force (which results in a larger distance between single nucleotides on the non-template strand), the increase in tension impairs the rebridization of the template to the non-template strand, preventing backtracking to happen.