DNA supercoiling, which occurs when coiling tension is generated ahead of the replication fork, is relieved by DNA gyrase. Supercoiling may also be involved in transcription regulation. Researchers discovered that enhancers operating over a long distance (2500 bp) are dependent on DNA supercoiling, while enhancers operating over shorter distances (110 bp) are not so dependent [Liu et al. (2001). Proc. Natl. Acad. Sci. USA 98:14,883–14,888]. Using a diagram, suggest a way in which supercoiling may positively influence enhancer activity over long distances.

Video transcript

Hi everyone. Let's look at our next question which of the following enzymes plays a major role in relaxing the super coiling DNA strands. Well as we recall as the D. N. A. D. N. A. Unwinds for the process of transcription, pulling those two strands apart and the double helix leads to super coiling and tangling in the remaining double strand behind it where you're opening it up. So we have an enzyme that prevents that. And the choice we're looking for is to see Topo I summaries and it achieves that relaxation by cutting the DNA strand at either one or both places and then that DNA strand untangles and is resealed. So that's how the super coiling is relaxed there. When we look at our other chances. Answer choices. Choice A is hell a case to case does the unwinding uh that which will actually cause the super coiling. So it's not what relaxes the super coiling isn't our correct answer. That means that choice D. All of the above is also not our answer. And then finally, Choice B. RNA polymerase. RNA polymerase is what synthesizes the RNA strand as the in the process of transcription. So that's not a correct answer is that's not what's involved in relaxing super coiling. So which of the following enzymes plays a major role in relaxing the super coiling DNA strands to a c. Topo I summaries. See you in the next video