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. Author manuscript; available in PMC: 2016 Sep 17.
Published in final edited form as: Mol Cell. 2015 Sep 17;59(6):1025–1034. doi: 10.1016/j.molcel.2015.08.012

Figure 5. Inhibition of the Core7 Helicase Activity by Bulky Lesion and XPA.

Figure 5

(A) XPA significantly enhanced Core7 helicase activities on a normal DNA (N_44/34), but had little stimulatory effect when CisPt was present on the top strand scanned by XPD (Pt_TOP).

(B) XPA had no stimulatory effect when CisPt was present on the bottom strand (Pt_BOT) either.

(C) AP lesions also inhibited the stimulatory effect of XPA on the Core7 helicase. Consistent results were obtained in multiple experiments with 1 or 2 nM DNA, and the latter is shown. Relative heli-case activities of Core7 in the presence of increasing amounts of XPA are plotted beneath each gel in (A)–(C).

(D and E) Comparison of DNA unwinding by Core7 alone or Core7 and XPA together at 1:1 molar ratio with or without DNA lesion. CisPt was on the strand scanned by XPD (D) or the complementary strand (E), and XPA enhances lesion-dependent stalling of Core7 by ~2-fold in both cases. Relative helicase activities are shown in the bar graph beneath. Error bars were estimated from triplicate measurements.