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Figure 3: Overall structure of the preincision complex. (a, b, c) Structure of the UvrB-dsDNA-ADP·Pi complex in three views. UvrB domains 1a, 1b, 2, and 3 and the β-hairpin are colored in green, pink, grey, cyan, and blue, respectively. The crosslinked cytosine on the inner strand (gold) is highlighted in red. ADP and Pi are shown in sticks. Experimentally determined UvrC incision sites on the inner strand are shown as red spheres. (d) Schematic illustrating the interactions between UvrB and DNA. Colour-coding for UvrB residues is as in (a-c). (e) 2 electron density (grey mesh), contoured at 1.5s, of ADP and Pi. (f) Close-up view of the extrahelical cytosine embedded inside the narrow hydrophobic pocket.