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. 2021 Nov 20;120(24):5454–5465. doi: 10.1016/j.bpj.2021.11.2884

Figure 5.

Figure 5

Folding and unfolding transition of the DNA hairpin detected on the surface of a single SUV tethered between two polystyrene beads. (A) Schematic diagram of the experimental setup to pull the DNA hairpin conjugated to a single lipid in the tethered SUV via one of the DNA handles. The other DNA handle was directly attached to the SUV lipids through biotin-streptavidin interactions. The SUV contained 98.47 mol % POPC, 0.5 mol % rhodamine-DOPE, 1 mol % DNA hairpin-labeled DOPE, and 0.03 mol % biotin-DSPE. (B) Bright-field fluorescence image of a single rhodamine-labeled SUV tethered between two optical trapped polystyrene beads. Note that untethered SUVs bound specifically to the right bead containing an excess of free biotinylated DNA handles. (C) FEC obtained by pulling the DNA hairpin to high force in the presence of the SUV (+SUV as depicted in A) or in the absence of SUV (−SUV) by directly attaching a biotinylated DNA hairpin molecule to the DNA handle on the right. (D) Time-dependent extension trajectory at constant mean force showing reversible unfolding/refolding of the DNA hairpin.