Trp operon transcription regulation by the repressor

Trp operon transcription regulation by the repressor, with tryptophan absent (a) and with tryptophan present (b)Trp operon transcription regulation by the repressor, with tryptophan absent (a) and with tryptophan present (b)

(a) Tryptophan absent Transcription Polycistronic mRNA The inactive repressor does not Repressor bind trpO, and transcription of the (inactive) operon genes occurs. (b) Tryptophan present No transcription Active repressor The repressor is activated by the core- pressor tryptophan and binds trpO to block operon gene transcription. Q Tryptophan (corepressor)