Overexpression and Purification of Bacterial Topoisomerase IV

Escherichia coli topoisomerase IV (topo IV) was discovered by Kato et al. (1), who showed that the predicted open reading frames from the parC and parE genes encoded proteins with a high degree of amino acid similarity to gyrA and gyrB, respectively. A new superhelical DNA relaxation activity could be demonstrated when extracts prepared from strains overproducing the parC and parE gene products were mixed together. ParC and ParE were subsequently purified (2,3), and it was demonstrated that they formed a heterotetramer (3) with ATP-dependent, type II topoisomerase activity (2,3).