biostudies-literaturePalle KNCI NIH HHS27767-27775https://www.ebi.ac.uk/biostudies/studies/S-EPMC2562070biostudies-literatureUnknown283(41)In eukaryotes, DNA topoisomerase I (Top1) catalyzes the relaxation of supercoiled DNA by a conserved mechanism of transient DNA strand breakage, rotation, and religation. The unusual architecture of the monomeric human enzyme comprises a conserved protein clamp, which is tightly wrapped about duplex DNA, and an extended coiled-coil linker domain that appropriately positions the C-terminal active site tyrosine domain against the Top1 core to form the catalytic pocket. A structurally undefined N-terminal domain, dispensable for enzyme activity, mediates protein-protein interactions. Previously, reversible disulfide bonds were designed to assess whether locking the Top1 clamp around duplex DNA would restrict DNA strand rotation within the covalent Top1-DNA intermediate. The active site proximThe Journal of biological chemistryDisulfide cross-links reveal conserved features of DNA topoisomerase I architecture and a role for the N terminus in clamp closure.PMC2562070CA58755CA111542CA21765Losasso CBenedetti PBjornsti MAPalle KPattarello Lvan der Merwe MfalseDisulfide cross-links reveal conserved features of DNA topoisomerase I architecture and a role for the N terminus in clamp closure.In eukaryotes, DNA topoisomerase I (Top1) catalyzes the relaxation of supercoiled DNA by a conserved mechanism of transient DNA strand breakage, rotation, and religation. The unusual architecture of the monomeric human enzyme comprises a conserved protein clamp, which is tightly wrapped about duplex DNA, and an extended coiled-coil linker domain that appropriately positions the C-terminal active site tyrosine domain against the Top1 core to form the catalytic pocket. A structurally undefined N-terminal domain, dispensable for enzyme activity, mediates protein-protein interactions. Previously, reversible disulfide bonds were designed to assess whether locking the Top1 clamp around duplex DNA would restrict DNA strand rotation within the covalent Top1-DNA intermediate. The active site proxim2008-01-01T00:00:00Z2008 Oct2026-05-01T22:42:44.906Z2019-03-27T00:18:44ZS-EPMC25620701869324410.1074/jbc.M80482620010.1074/jbc.m804826200