lac Promoter)lac Operator lacZ lacY lacA RNA Transcription blocked polymerase W Repressor (a) 2.Lac operon lac Promoter)lac Operator lacZ lacy lacA Mutation 1 RNA ◆ Transcription proceeds polymerase → Mutation 2 Repressor () Inducer 2012 Pearson Education,Inc. Mutation 3 Mutation 4 The process of enzyme induction using a repressor
The process of enzyme induction using a repressor. Mutation 1 Mutation 2 Mutation 3 Mutation 4 2. Lac operon
上游充通大淫 SHANGHAI JIAO TONG UNIVERSITY 8.6 Positive Control of Transcription -Activator mediated regulation by protein-DNA binding Positive control-a regulator protein promotes the binding of RNA polymerase,thus acting to increase mRNA synthesis.正调控 Activator protein and activator binding site话化子 与活化位点 Inducer binds to activator and helps it bind to DNA 化子与诱导物结合后可结合于DNA Chen Feng,Shanghai Jiao Tong University
Chen Feng, Shanghai Jiao Tong University 8.6 Positive Control of Transcription ----Activator mediated regulation by protein-DNA binding Positive control- a regulator protein promotes the binding of RNA polymerase, thus acting to increase mRNA synthesis. 正调控 Activator protein and activator binding site 活化子 与活化位点 Inducer binds to activator and helps it bind to DNA 活 化子与诱导物结合后可结合于DNA
8.6.1 Mechanism of positive control: Inducer and activator诱导物与活化子 Activator- binding site ma/Promoter malE malF malG RNA No transcription polymerase Maltose activator protein (a) 2012 Pearson Education,Inc. (a)In the absence of an inducer,neither the activator protein nor the RNA polymerase can bind to the DNA. 当无诱导物时，活化子与DNA聚合酶不能结合DNA
8.6.1 Mechanism of positive control: Inducer and activator诱导物与活化子 (a)In the absence of an inducer, neither the activator protein nor the RNA polymerase can bind to the DNA. 当无诱导物时,活化子与DNA聚合酶不能结合DNA
Activator- binding site mal Promoter) malE malF malG RNA →→ Transcription proceeds polymerase Maltose activator protein Inducer (b) 2012 Pearson Education,Inc. (b)An inducer molecule binds to the activator protein,which in turn binds to the activator binding site.This allows RNA polymerase to bind to the promoter and begin transcription. In malEFG operon,the activator protein would be the maltose activator protein and the inducer would be maltose.麦芽糖 malEFG操纵子
(b) An inducer molecule binds to the activator protein, which in turn binds to the activator binding site. This allows RNA polymerase to bind to the promoter and begin transcription. In malEFG operon, the activator protein would be the maltose activator protein and the inducer would be maltose.麦芽糖 malEFG操纵子