Fig. 5
From: HTLV-1 Tax plugs and freezes UPF1 helicase leading to nonsense-mediated mRNA decay inhibition
Tax blocks UPF1 translocation. a Schematic representation of the DNA substrate used for the magnetic tweezers' set-up. b Experimental magnetic tweezer traces showing the activity of UPF1-HD under a saturating concentration of ATP (blue line). The trace showing the force monitoring (red line) is shown above the recorded track. The number of unwound bases is deduced from the molecular extension Z(t) obtained at F = 10 piconewton (pN). From 1000 to 2500 s, the helicase unwound the ~1200 bp DNA hairpin. From 2500 to 3200 s, the DNA hairpin refolded while the UPF1-HD translocated on the ss-DNA. c The upper and lower panels show two types of enzymatic activity detected for UPF1-HD in the presence of Tax. On the upper panel, UPF1-HD is unwinding the DNA hairpin between 3000 and 3625 s before dissociation induced by Tax binding. On the lower panel, UPF1-HD is unwinding the whole DNA hairpin between 500 and 1750 s and translocating between 1750 and 1920 s on the ss-DNA. Tax blocks UPF1-HD translocation twice between 1920 and 2370 s and 2414 and 3660 s. A sliding event and the final dissociation of UPF1-HD can be observed at 2372 and 3660 s, respectively
