In an arabinose-inducible system, what is the role of the araC gene on the plasmid when arabinose is present?

In an arabinose-inducible system, what is the role of the araC gene on the plasmid when arabinose is present?

• A. It encodes the AraC protein that interacts with RNA polymerase to activate transcription from the PBAD promoter
• B. It encodes a repressor that blocks PBAD in the presence of arabinose
• C. It codes for a fluorescent protein
• D. It stabilizes the plasmid in the cell

Answer: (A)

The main idea is how the AraC regulator works at the PBAD promoter when arabinose is present. The araC gene on the plasmid encodes the AraC protein. When arabinose is in the environment, AraC binds it and changes shape so it can interact with RNA polymerase at the PBAD promoter, recruiting the polymerase and initiating transcription of the downstream gene. In this context, AraC acts as an activator, turning on expression in response to arabinose. This is why the correct description is that AraC encodes a protein that interacts with RNA polymerase to activate transcription from PBAD.

The main idea is how the AraC regulator works at the PBAD promoter when arabinose is present. The araC gene on the plasmid encodes the AraC protein. When arabinose is in the environment, AraC binds it and changes shape so it can interact with RNA polymerase at the PBAD promoter, recruiting the polymerase and initiating transcription of the downstream gene. In this context, AraC acts as an activator, turning on expression in response to arabinose. This is why the correct description is that AraC encodes a protein that interacts with RNA polymerase to activate transcription from PBAD.