Question

Why is DNA gyrase (topoisomerase II) important in reducing supercoiling and torsional strain during DNA unwinding, and how does it achieve this by making double-stranded breaks in the DNA and passing another segment of the helix through the break before resealing it?

Answer 1

DNA gyrase, or topoisomerase II, plays a critical role in DNA replication by managing supercoiling and torsional strain. It works by making double-stranded breaks, passing another segment through the break, and then resealing the DNA to maintain the molecule's integrity.

Step-by-step explanation:

DNA gyrase, also known as topoisomerase II, is a critical enzyme that prevents the overwinding or supercoiling of DNA during the replication process. As the double helix unwinds, it introduces positive supercoils ahead of the replication fork, causing torsional strain. To prevent the strands from becoming too tightly wound, which could lead to breakage or errors during replication, DNA gyrase makes controlled double-stranded breaks.

The key function of DNA gyrase is to manage the topological changes during replication, ensuring that the DNA is in an accessible state for essential cellular processes like transcription and further replication. This action is critical for maintaining the integrity of the DNA molecule and ensuring the fidelity of the genetic information during cell division.