In: Biology
This operon is also regulated by transcription attenuation. How does this attenuation work?
Answere :
Attenuation is a type of gene regulation in some bacterial operons, in which transcription is initiated but terminates prematurely before the transcription of the structural genes. In this mechanism, translation controls transcription.
Attenuation takes place in a number of operons that encode enzymes participating in the biosynthesis of amino acids.
Attenuator is a secondary structure that present in the 5′ untranslated region of mRNA in operon and causes the premature termination of transcription. It is called as 5' UTR of mRNA.
The trp operon is regulated both by repression and by attenuation.
In attenuation, transcription is initiated but terminates prematurely.
When tryptophan levels are low, the ribosome stalls at the tryptophan codons and transcription continues.
When tryptophan levels are high, the ribosome does not stall at the tryptophan codons, and the 5′ UTR adopts a secondary structure that terminates transcription before the structural genes can be copied into RNA (attenuation).