Which component of the TRP operon directly interacts with tryptophan?

The correct answer is the operator, which is the component of the TRP operon that directly interacts with tryptophan. In the TRP operon, the operator is a DNA segment where regulatory proteins bind to control the transcription of downstream genes involved in tryptophan biosynthesis.

When tryptophan levels are high, it binds to a regulatory protein, known as the trp repressor. The binding of tryptophan to the trp repressor causes a conformational change, allowing the trp repressor to bind to the operator. This interaction effectively blocks RNA polymerase from transcribing the genes needed for tryptophan production, thereby preventing further synthesis of the amino acid when it is already abundant.

Understanding this mechanism is crucial because it illustrates how feedback inhibition operates in metabolic pathways. The operator’s role in the regulation of gene expression based on metabolite levels emphasizes the importance of conditional control over metabolic processes.