Topoisomerases are enzymes that transiently make breaks in DNA, to prevent the build-up of topological stress and tangles as the genome is transcribed, replicated or repaired. Type II topoisomerases have been postulated to use a two-metal mechanism to break duplex DNA. Now, the structure of the DNA-binding and cleavage core of a yeast type II topoisomerase has been solved, showing that the enzyme uses a variation of the classical mechanism, and can also carry out the type of cleavage performed by type IA topoisomerases.
A novel and unified two-metal mechanism for DNA cleavage by type II and IA topoisomerases