Topoisomerase

A topoisomerase is one of a group of enzymes that unwind and wind DNA in order to help the creation of DNA structures.

DNA is in a helix/spiral which helps make the structure of DNA strong and stable. However, when undergoing DNA replication, the spiral needs to be untwisted, and when spirals are being untwisted knots, and breaks can happen. When studying the structure of DNA, James D. Watson and Francis Crick knew that there was need for an enzyme to overcome this problem.

Topoisomerase binds to either side of the DNA strands and allows the DNA to be untangled or unwound.

Topoisomerase Media

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  Illustration of DNA topology and how supercoiling is related to changes in linking number, twist, and writhe in addition to the description of higher order knotting and catenation topological features of closed circular DNA.

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  Figure 6. Structures of antibiotic compounds that target bacterial DNA gyrase and topoisomerase IV.

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  Figure 7. Structures of antitumor compounds that target human topoisomerases.

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  Paused RNA polymerase and limited, short-term topo IIβ-induced DNA double-strand break. The 5' ends of DNA are covalently joined to tyrosine within the topo IIβ dimer-PARP-1 complex. The non-homologous end joining DNA repair pathway components DNA-PKcs, Ku70/Ku80 and DNA ligase are also closely associated with the topo IIβ dimer-PARP-1 complex.