A novel norindeniosoquinoline structure reveals a common interfacial inhibitor paradigm for ternary trapping of the topoisomerase I-DNA covalent complex

摘要

We demonstrate that five topoisomerase I (Top 1) inhibitors (two indenoisoquinolines, two camptothecins, and one indolocarbazole) each intercalate between the base pairs flanking the cleavage site generated during the Top1 catalytic cycle and are further stabilized by a network of hydrogen bonds with Top1. The interfacial inhibition paradigm described for Top1 inhibitors can be generalized to a variety of natural products that trap macromolecular complexes as they undergo catalytic conformational changes that create hotspots for drug binding. Stabilization of such conformational states results in uncompetitive inhibition and exemplifies the relevance of screening for ligands and drugs that stabilize (“trap”) these macromolecular complexes.