What is negative supercoiling of DNA?
Positive supercoiling of DNA occurs when the right-handed, double-helical conformation of DNA is twisted even tighter (twisted in a right-handed fashion) until the helix begins to distort and “knot.” Negative supercoiling, on the other hand, involves twisting against the helical conformation (twisting in a left-handed …
What relaxes supercoiled DNA?
Supercoiled DNA is under too much tension to be separated, so an extra step is required before replication and transcription can occur. DNA gyrase relaxes supercoiled DNA by cutting it, allowing rotation to occur, and then reattaching it.
What causes supercoiling of DNA?
When the DNA helix has the normal number of base pairs per helical turn it is in the relaxed state. Supercoiling occurs when the molecule relieves the helical stress by twisting around itself. Overtwisting leads to postive supercoiling, while undertwisting leads to negative supercoiling.