Molecular control of DNA superstructure
The appropriate organization and management of chromosomal strands depends on the action of enzymes that modulate DNA supercoiling, looping, and topology. How these factors interact with target DNA segments to productively disentangle strands and actively control DNA twist and writhe is a long-standing issue in the field. We have helped establish how type IIA topoisomerases bind and cleave duplex DNA and how ATP binding and hydrolysis coordinate the passage of a second DNA segment through this break. We have also helped to define the evolution of different type II topoisomerase families, connecting one branch of this group to meiotic recombination processes, and have begun to establish how type II topoisomerases interface with SMC-family condensin type factors and are regulated by partner protein interactions.