DNA topoisomerase II is an essential enzyme involved in the management of DNA supercoiling, which is crucial for various cellular processes, including DNA replication, transcription, recombination, and chromosome condensation. Also known as DNA gyrase or topoisomerase II enzyme, it plays a critical role in resolving topological constraints in DNA by introducing transient single-stranded breaks in the DNA molecule.
The DNA topoisomerase II enzyme has a complex structure and executes two major functions, namely DNA strand passage and DNA cleavage and rejoining. In the process of DNA strand passage, it catalyzes the transport of one DNA duplex through another, thus altering the topological state of DNA molecules. This allows the DNA to relieve torsional stress and maintain proper DNA structure and function.
Moreover, DNA topoisomerase II enzyme acts as a molecular scissor by inducing double-stranded DNA cleavage, creating a temporary gap in the DNA helix. It then captures another segment of DNA and relocates it across the cleaved DNA strands before resealing the break. This process enables the release of supercoils and other topological constraints, ensuring the proper organization and function of DNA.
The activity of DNA topoisomerase II is tightly regulated and often requires the input of ATP (adenosine triphosphate), an energy molecule, for its catalytic functions. Dysregulation or inhibition of DNA topoisomerase II can lead to cellular dysfunction, DNA damage, and genome instability, making it a target for certain anti-cancer drugs that prevent the enzyme from properly managing DNA topology.
