Structural, mechanistic and functional insights into topoisomerase II

Topoisomerases are nuclear enzymes that regulate the overwinding or underwinding of DNA helix during replication, transcription, recombination, repair, and chromatin remodeling. These enzymes perform topological transformations by providing a transient DNA break, through which the unique problems of DNA entanglement that occur owing to unwinding and rewinding of the DNA helix can be resolved. In mammals, topoisomerases are classified into two types, type I topoisomerase (Top1) and type II topoisomerase (Top2), depending on the number of strands cut in one round of action. Top1 induces single-strand breaks in DNA, and Top2 induces double-strand breaks. In cells from vertebrate species, there are two forms of Top2, designated alpha and beta. Top2α is involved in the cellular proliferation and pluripotency, while Top2β plays key roles in neurodevelopment. In this review, we cover recent advances in structural, mechanistic and functional insights into Top2.