Untangling the Double Helix: DNA Entanglement and the Action of the DNA Topoisomerases

The problem of unraveling two intertwined strands during the duplication of DNA was recognized shortly after the proposal of the DNA double helix structure in 1953. A group of enzymes called DNA topoisomerases solve this problem by breaking and rejoining DNA molecules in a controlled manner, thereby allowing strands to be passed through each other and thus untangled not just during DNA replication, but also during many other basic cellular processes. Because of their intimate involvement in...