Figure 1.
Tdp1 in the repair of the stalled Top1–DNA complex: (A) noncovalent Top1–DNA complex; (B) transient Top1–DNA complex, which is trapped in the presence of a Top1 inhibitor; (C) the stalled Top1–DNA complex (cleavage complex) is repaired by Tdp1 via a transient Tdp1–DNA covalent intermediate; (D) Top1 is released and the Tdp1–DNA covalent intermediate resolved by hydrolysis; (E) 3′-phospho–DNA–end product.