Of Topo and Maxwell's Dream

摘要

Discovery of unexpected greatness in nature is always delightful. We are treated on page 690 of this issue to a report by Rybenkov et al. (1) of grandiose behavior among the DNA topoisomerases, enzymes that change the topology of DNA. They show that the most abundant eukaryotic topoisomerase II (topo II) (2) and the closely related Escherichia coti topoisomerase IV (topo IV) (3) can each--almost without error--recognize and undo a knot in a DNA circle many times larger than themselves, forcing a population of coiled, catenated, and knotted DNAs to an untangled state far from equilibrium.