If enhancers are located far from promoters, which mechanism allows them to regulate transcription?

• A. Direct base pairing between enhancer and promoter.
• B. Transcription factors bound at enhancers degrade the promoter.
• C. Chromatin looping brings bound factors into proximity with the promoter.
• D. Enhancers regulate transcription by degrading the promoter.

Answer: (D)

The key idea is that enhancers regulate gene transcription by looping the DNA so the enhancer-bound proteins come into contact with the promoter and the transcription machinery, even when they are far apart in the linear sequence. This chromatin looping brings transcription factors, coactivators, and often the Mediator complex and cohesin into close proximity with the promoter, enabling RNA polymerase II recruitment and efficient initiation. It’s not about base pairing between enhancer and promoter DNA, and enhancers don’t act by degrading the promoter. This looping mechanism explains how distant elements can control transcription from a distance.