regulation by cyclic AMP (cAMP) levels, and its interaction with the Catabolite Activator Protein, CAP. Slide: Cooperative binding of cAMP-CAP and RNAP on the lac promoter X-ray structure of CAP-cAMP bound to DNA Catabolite control of the lac operon. Think big picture: with the lac operon, there are elements of both negative and positive control o The tryptophan trp operon: two kinds of negative regulation There?s a repressor protein. Also, the mRNA binds with itself where there is complementarity downstream. There?s a Trp Leader that controls via attenuation. If there?s a lot of tryptophan, then the ribosomes work pretty close to the RNA polymerase, which causes the mRNA to bind to itself right next to the ribosome, causing it to fall off of the mRNA. This is a very fine-tuned, complicated process. o The arabinose (ara) operon PBAD promoter: very tight, precise control. Used a lot in biotechnology for that reason. Key features of Arabinose regulation
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