Which description best characterizes the function of the AraC protein?

Which description best characterizes the function of the AraC protein?

• A. A structural component of the cell wall
• B. A metabolic enzyme in glycolysis
• C. A transcriptional regulator that activates PBAD in presence of arabinose
• D. A membrane receptor

Answer: (C)

AraC functions as a transcriptional regulator that activates PBAD in the presence of arabinose. It controls the arabinose utilization genes by binding to the PBAD promoter region and, when arabinose is available, changing shape to recruit RNA polymerase and initiate transcription. In the absence of arabinose, AraC binds in a way that represses transcription by looping the DNA. This regulatory role is distinct from being a structural cell-wall component, a metabolic enzyme in glycolysis, or a membrane receptor, which is why this description best captures its function in controlling gene expression in response to arabinose.

AraC functions as a transcriptional regulator that activates PBAD in the presence of arabinose. It controls the arabinose utilization genes by binding to the PBAD promoter region and, when arabinose is available, changing shape to recruit RNA polymerase and initiate transcription. In the absence of arabinose, AraC binds in a way that represses transcription by looping the DNA. This regulatory role is distinct from being a structural cell-wall component, a metabolic enzyme in glycolysis, or a membrane receptor, which is why this description best captures its function in controlling gene expression in response to arabinose.