TBP causes an increase in the FRET observed from single immobilized consensus TATA DNA molecules. (A) The single-molecule surface configuration for monitoring TBP-induced DNA bending. When TBP bends the immobilized DNA it causes an increase in FRET efficiency. (B) The consensus TATA construct exhibits constant low FRET in the absence of TBP. The donor dye (green), the acceptor dye (red), and sum of the two dyes (gold) did not change over the course of imaging (upper panel). The calculated FRET at each time point is shown in blue and the derived FRET state of 0.24 is shown in black (lower panel). For the purpose of display, these data were smoothed by averaging the values at 3 time points. (C) TBP causes an increase in FRET consistent with DNA bending. The donor and acceptor dyes show anti-correlated changes in signal intensity (upper panel) and an increase in calculated FRET efficiency (lower panel) at 4 seconds, indicating TBP bent the DNA. At 47 s, the acceptor dye photobleached, causing emission from the donor dye to increase. For the purpose of display, these data were smoothed by averaging the values at 3 time points.