Fig. 1

| Accelerated dissociation of donor strands. (a) A scheme of FRET-PAINT microscopy. Acceptor fluoresces only via FRET and its signal is collected by a high-speed sCMOS camera. Donor signal is rejected by a band-pass filter. (b) DNA strands used for the experiments: docking (black), donor (blue), and acceptor (red) strands. A length of donor strand was controlled by truncating the 5′-end of the donor strand. Acceptor and donor fluorophores are labeled at the designated positions. (c-f) Dissociation time of donor strands with the length of 9 nt (c), 8 nt (d), 7 nt (e), and 6 nt (f). Left panels show representative FRET time traces, in which high and low FRET states correspond to the bound and unbound states, respectively. Right panels show histograms of dissociation times. The dissociation times were obtained by fitting the histograms with an exponential decay function: 670 ms (9 nt), 63 ms (8 nt), 4.8 ms (7 nt), and 3.7 ms (6 nt)