Figure 1.

Attenuation of CAG repeat expansion through repair of 8-oxoG in the hairpin loop and Mus81/Eme1 cleavage. Repair of an 8-oxoG in the loop region of a CAG hairpin and Mus81/Eme1 cleavage activity were examined with substrates containing a (CAG)₇ (left panel) or (CAG)₁₄ hairpin (right panel) with an 8-oxoG in the hairpin loop region. Lanes 1 and 14 correspond to substrates only. Lanes 2 and 15 correspond to reaction mixtures with 10 nM OGG1. Lanes 3 and 16 correspond to reaction mixtures with 10 nM OGG1 and 50 nM APE1. Lanes 4 and 17 correspond to reaction mixtures with 250 nM Mus81/Eme1, 5 nM pol β, 10 nM OGG1, 50 nM APE1 and 5 nM LIG I in the absence of FEN1. Lanes 5–6 and lanes 18–19 correspond to reaction mixtures with 10 nM OGG1, 50 nM APE1, 10 nM FEN1 and 5 nM LIG I in the absence or presence of 250 nM Mus81/Eme1. Lanes 7–8 and lanes 20–21 correspond to reaction mixtures with 10 nM OGG1, 50 nM APE1, 5 nM pol β, 10 nM FEN1, 5 nM LIG I in the absence or presence of 250 nM Mus81/Eme1. Lanes 9–10 and 22–23 correspond to reaction mixtures with 10 nM OGG1, 50 nM APE1, 250 nM Mus81/Eme1 in the absence and presence of 5 nM pol β. Lanes 11–12 and lanes 24–25 represent reaction mixtures with 10 nM OGG1, 50 nM APE1, 250 nM Mus81/Eme1 and 5 nM FEN1 in the absence and presence of pol β. Lanes 13 and 26 correspond to a series of synthesized size markers (M) for illustrating the size of repaired products and Mus81/Eme1 cleavage products. Substrates were ³²P-labeled at the 5′-end of the hairpin-containing strand (expanded/uncut strand). Substrates are illustrated schematically above the gels. A scheme that indicates removal of a CAG repeat hairpin with an 8-oxoG is illustrated below the gels. The sizes of Mus81/Eme1 cleavage products are illustrated in nucleotides.