trp-Operon

The tryptophan operon, short trp operon is an operon of Escherichia coli, such as playing an important role in the intracellular synthesis of tryptophan in bacteria. This operon is only activated when the cell must make tryptophan itself, because the amino acid is not located in the surrounding medium. The operon is (in addition to promoter and operator ) from five structural genes coding for the five specific proteins. Whose transcription is regulated by the operator, depending on the concentration of tryptophan. The encoded enzymes are responsible for a precursor in five steps, the amino acid tryptophan is produced. The transcribed by the regulatory gene and translated from the mRNA repressor (→ aporepressor ) remains inactive as no tryptophan is present to enter with him a bond. When tryptophan was prepared it binds to the repressor and is activated by binding to the operator. Thus, tryptophan production of self- regulates its own, by the principle of negative feedback is applied.

One speaks of a final repression, as the product of a synthesis itself acts indirectly on this.

The structural genes of the trp operon are:

• TrpE
• Trp
• TrpC
• TrpB
• TrpA