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29 Αυγ 2023 · The ribosome translating the mRNA moves past through the trp codons in region 1 without stalling. It leads to a termination hairpin in regions 2 and 3. The termination hairpin prompts the RNA polymerase to terminate transcription prematurely before reaching the structural genes.
3 Σεπ 2022 · Trp Operon. The tryptophan operon is the regulation of transcription of the gene responsible for biosynthesis of tryptophan. The tryptophan (trp) operon contains five structural genes encoding enzymes for tryptophan biosynthesis with an upstream trp promoter (Ptrp) and trp operator sequence (Otrp). Structural genes are TrpE, TrpD, TrpC, TrpB ...
In the present paper I will focus on our current understanding of the RNA-based regulatory mechanisms used by Escherichia coli and Bacillus subtilis in controlling expression of the tryptophan biosynthetic operon.
The trp operon is regulated by the trp repressor protein. Trp repressor protein binds to tryptophan and undergoes a conformational change which allows it to bind to the trp operator region (downstream of the promoter).
Transcription of the trp operon is highly regulated. Initiation of transcription at the trp promoter is regulated by the tryptophan-activated trp repressor. The repressor can bind at multiple operator sites located in the promoter region.
The trp operon contains five structural genes: trpE, trpD, trpC, trpB, and trpA, which encode the enzymes needed to synthesize tryptophan. It also contains a repressive regulator gene called trpR. When tryptophan is present, the trpR protein binds to the operator, blocking transcription of the trp operon by RNA polymerase.
The trp Operon - A Repressible Operon. E. coli can synthesize tryptophan using enzymes that are encoded by five structural genes located next to each other in the trp operon, as shown in Figure \(\PageIndex{2}\). When environmental tryptophan is low, the operon is turned on.
