Fig 12-3-Elongation and termination elongation Elongation s Termination RNA olymerase terminates. and releases RNA 16
16 Fig 12-3-Elongation and termination Termination Elongation
1-2 Targeting promoter binding: Many promoters are A regulated by activators that help rnap bind DNa and b 3. repressors that block the F. binding At many promoters, RnaP binds weakly Lac operon is a good example 17
17 1-2 Targeting promoter binding: Many promoters are regulated by activators that help RNAP bind DNA and by repressors that block the binding ➢ At many promoters, RNAP binds weakly ➢ Lac operon is a good example Principles of Transcription Regulation
Fig 16-1 a. Absence of RNA polymerase Regulatory Proteins (operator) basal level of transcription activator operator binding site promoter b. To Control b no transcription Expression repressor C. To Activate RNA polymerase spontaneous activator isomerization Expression leading to activated level of transcription
18 a. Absence of Regulatory Proteins (operator) b. To Control Expression c. To Activate Expression Fig 16 - 1
1-3 Targeting transition to the open complex: Some Activators Work b Allostery and Regulate Steps after RNA Polymerase Binding RNA polymerase no spontaneous Fig 16-2 isomerization and thus no transcription activator binding site promoter Examples Activator promoter Ntrc gIRA RNA polymerase Merr merT activator activated level of transcription
19 1-3 Targeting transition to the open complex: Some Activators Work by Allostery and Regulate Steps after RNA Polymerase Binding Fig 16-2 Examples: Activator promoter NtrC glnA MerR merT
Some promoters are inefficient at more than one step and can be mechanis y more than one activated b Repressors can work in ways other than just blocking the promoter binding. For example, inhibition of the transition to the open complex. 20
20 Some promoters are inefficient at more than one step and can be activated by more than one mechanism Repressors can work in ways other than just blocking the promoter binding. For example, inhibition of the transition to the open complex