Tryptophan operon (trp operon ) Structure and Attenuation control In Bengali
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The Tryptophan Operon of E.coli which control the biosynthesis of amino acid tryptophan easy example of repressible operon.The trp operon consists of five structural gene ( trpE,trpD,trpC,trpB,trpA) which produce compound of three enzyme. These enzyme convert chorismate into tryptophan. The regulator gene of trp operon encodes a repressor that alone cannot bind to the operator gene. Like the lac repressor the Tryptophan repressor has two binding sites, one for operator site of DNA Tryptophan. When tryptophan binds with the repressor, a conformational changes occur in the repressor that makes it capable of binding to DNA at the operator site. When the operator is occupied by the Tryptophan-represssor, RNA polymerase cannot bind to the promoter and the structural gene cannot be transcribed.Thus when cellular levels of tryptophan are low transcription of the trp operon takes place and more tryptophan is synthesise, when cellular level of tryptophan are high transcription of the trp operon is inhibited and the synthesis of of more tryptophan does not takes place.
Attenuation is a mechanism for the regulation of transcription of some bacterial operons by aminoacyl-tRNAs. It was first discovered by Yanoksky in 19
The Tryptophan Operon of E.coli which control the biosynthesis of amino acid tryptophan easy example of repressible operon.The trp operon consists of five structural gene ( trpE,trpD,trpC,trpB,trpA) which produce compound of three enzyme. These enzyme convert chorismate into tryptophan. The regulator gene of trp operon encodes a repressor that alone cannot bind to the operator gene. Like the lac repressor the Tryptophan repressor has two binding sites, one for operator site of DNA Tryptophan. When tryptophan binds with the repressor, a conformational changes occur in the repressor that makes it capable of binding to DNA at the operator site. When the operator is occupied by the Tryptophan-represssor, RNA polymerase cannot bind to the promoter and the structural gene cannot be transcribed.Thus when cellular levels of tryptophan are low transcription of the trp operon takes place and more tryptophan is synthesise, when cellular level of tryptophan are high transcription of the trp operon is inhibited and the synthesis of of more tryptophan does not takes place.
Attenuation is a mechanism for the regulation of transcription of some bacterial operons by aminoacyl-tRNAs. It was first discovered by Yanoksky in 19
4 سال پیش
در تاریخ 1399/02/10 منتشر شده
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