FIGURE 5.

ScMre11 catalyzes unwinding of flayed duplex DNA and Holliday junction containing 3′ ssDNA overhangs. The indicated ³²P-labeled DNA substrate possessing 20-mer ssDNA overhangs (3 nm) either at the 3′ or 5′ ends (depicted in the gel image at the top) was incubated in a buffer containing 20 mm Tris-HCl (pH 7.5), 1 mm DTT, 100 μg/ml BSA, 0.1 mm EDTA, and the reaction products were separated and visualized as described under “Experimental Procedures. ” Lane 1 (marked C), DNA substrate alone; lane 2 (marked Δ), heat-denatured DNA substrate; lanes 3–9, reaction mixtures contained 100, 200, 300, 400, 500, 600, and 700 nm ScMre11, respectively. The filled triangle on top of the gel image denotes the increasing concentration of ScMre11. Reaction products were separated and visualized as described under “Experimental Procedures.” a, flayed duplex DNA with 20-mer 5′ ssDNA overhang; b, flayed duplex with 20-mer 3′ ssDNA overhang; c, Holliday junction with 20-mer 5′ ssDNA overhang; d, Holliday junction with 20-mer 3′ ssDNA overhang.