FIGURE 1.

Twinkle unwinding activity on DNA replication structures. A–D, purified recombinant Twinkle helicase, designated in hexamer concentration, was incubated with the indicated replication fork DNA substrates 1–4 (0.5 nm) at 37 °C for 30 min as described under “Experimental Procedures.” Proteinase K-digested reaction products were resolved on non-denaturing 12% polyacrylamide gels. Representative gel images from at least three independent experiments are shown. Filled triangle, heat-denatured DNA substrate control. E, quantitative analysis of percent DNA substrate unwound from A to D. Fork with single-stranded 5′ and 3′ arms, filled circle; fork with 5′ single-stranded arm, open circle; fork with 3′ single strand arm, filled triangle; fork with double-stranded 5′ and 3′ arms, open triangle. Average values of at least three independent experiments with standard deviations indicated by error bars are shown.