Movie S4.

Unwinding of a λ DNA molecule in a solution of 50 nM RecQ and AF546SSB. Initially, the DNA is apparent due to the binding of the fluorescent YO-PRO-1 dye. The flow, when on, is from left to right in the movie, and RecQ and AF546SSB fill the channel 58 s into the movie. The elapsed time is indicated in hours:minutes:seconds. (Scale bar, 5 μm.)