Question

Suppose that you used site-specific mutagenesis to modify the trpL sequence such that the two UGG Trp codons at positions 54-56 and 57-59 in the mRNA leader sequence were changed to GGG Gly codons. Will attenuation of the trp operon still be regulated by the presence or absence of tryptophan in the medium in which the E. coli cells are growing? Explain

Answer 1

The trp operon, found in E. coli bacteria, is a group of genes that encode biosynthetic enzymes for the amino acid tryptophan.The trp operon is regulated by the trp repressor and attenuation mechanism. In E.Coli,translation-mediated transcriptional attenuation provides an additional level of control that results in more stringent regulation that could be achieved by repression of initiation alone.

In trp operon, the site of attenuation is located downstream of the transcription start site. if tryptophan is abundant, most transcription terminates at this site; only if tryptophan is scarce does transcription continue to yield functional trp mRNA.