Fig. 4.
Effect of the number of damages in the λ DNA substrate on the diffusion constants and binding lifetimes of Fpg, Nei, and Nth. Undamaged (light gray), low-dose (gray), and high-dose (dark gray) treated λ DNA substrates were used in the single-molecule assay to measure glycosylase diffusion constants. See Fig. S1 for how the number of damages per molecule was determined. (A) Diffusion constants Dtraj were calculated from the slope of the first 25% of the MSD plot for WT Fpg, Nei, and Nth and the wedge mutants diffusing on damaged DNA (see Fig. S2 for Dint distributions, Table S1 for specific values and numbers of observations for each condition, and also Movie S3). Ordinate tick marks indicate powers of 10. (B) Characteristic binding lifetimes were calculated from single-exponential fits to binding lifetime histograms for each trajectory that initiates with glycosylase binding and terminates at dissociation from the DNA. Error bars represent SEM. *P < 0.05; ***P < 0.001.