DNA topoisomerases interact with the supercoiled domain on transcriptionally active TUs.

<p>Advancement of RNA polymerase on DNA template generates waves of positive supercoils ahead and negative supercoils behind (Twin-supercoiled domain). Topo I is recruited to sites where negative supercoils are prominent while DNA gyrase occupies the region with positive supercoils. Together these enzymes maintain the transcription template topology for optimal transcription.