Biochemistry 2280A Lecture Notes - Lecture 3: Helix-Turn-Helix, Lac Repressor, Trp Operon
Document Summary
Two genes a and b- want differential transcription of a vs b. When these sigma"s are present they bind to the rna polymerase core and bind to the -35 and -10 subset of promoters: genes specific regulatory proteins: Dynamic: responsive to environmental changes (turning an individual promoter on or off in response to environment) Operator: a short region of dna found within a bacterial promoter that negatively regulates expression of the adjacent gene. Trp repressor: the protein that binds the trp operator. 5 genes are required for tryptophan biosynthesis are transcribed from a common promoter: makes the 5 enzymes. Trp operator binds a protein the trp repressor. Two key elements: trp operator located in between the -10 and -35 regions, dna element, trp repressor (protein that binds to operator, protein that binds to the dna. Trp repressor binds to tryptophan when theres lots of tryptophan in the cell. The trp repressor=tryptophan complex binds the trp operator dna with high affinity.