Extended Data Fig. 2: Donor-only dwell time is inversely correlated with ionic strength of buffer solution.
From: GAGA zinc finger transcription factor searches chromatin by 1D–3D facilitated diffusion
a, Representative trajectories showing Cy5-cognate DNA bound by Cy3-GAF-DBD in 0, 25, 50, or 100 mM NaCl. Grey-highlighted durations indicate donor-only dwell times. b, Representative trajectories showing Cy5-cognate DNA bound by Cy3-GAF-DBD in 0, 1, 5, 7.5, or 10 mM MgCl2. The sensitivity of FRET dynamics to salt concentration suggests that the transient donor-only periods are not due to photo-induced blinking. c, Donor-only dwell time (τ from fitting 1-CDF to a single-exponential decay; see Methods) as a function of NaCl concentration (N = 119, 147, 109, 23 for 0 mM, 25 mM, 50 mM, and 100 mM, respectively), and d, MgCl2 concentration (N = 177, 128, 116, 149 for 0, 1, 5, and 7.5 mM, respectively). Data are represented as mean values +/- standard errors for a single-component exponential decay fit. DNA is the same as cognate DNA in Fig. 1. e, 1-CDFs for dwell times reported in Fig. 1h with fits to a single-component exponential decay function (ExpDec1 in OriginPro). Replicates were fit individually and their average τ is reported as the final dwell time.
