3. Targeting promoter binding many promoters are regulated by activators k 活蛋白) that help rnap bind dna( recruitment) and by repressors(阻遏蛋白) that block the binding RNAP binds many promoters weakly (?) activators that contain two binding sites to bind a DNA sequence and RNAP simultaneously can s enhance the RNAP affinity with the promoters and thus increases gene transcription This is called recruitment regulation(招募调控) On the contrary, Repl lessors can bind to the operator inside of the promoter region which prevents RNAP binding and the transcription of the target gene
17 3. Targeting promoter binding: many promoters are regulated by activators (激 活蛋白) that help RNAP bind DNA (recruitment) and by repressors(阻遏蛋白)that block the binding. RNAP binds many promoters weakly (?), activators that contain two binding sites to bind a DNA sequence and RNAP simultaneously can enhance the RNAP affinity with the promoters, and thus increases gene transcription.This is called recruitment regulation (招募调控). On the contrary, Repressors can bind to the operator inside of the promoter region, which prevents RNAP binding and the transcription of the target gene. Principles of Transcription Regulation
Fig 16-1 a. Absence of RNA polymerase Regulatory Proteins basal level expression basal level of transcription operator b. Repressor binding site omoter binding to the b no transcription repressor operaTor represses expression c. Activator RNA polymerase spontaneous isomerization binding activates leading to activated level of transcription expression promoter
18 a. Absence of Regulatory Proteins: basal level expression b. Repressor binding to the operator represses expression c. Activator binding activates expression Fig 16 - 1
4 Targeting transition to the open complex E,A| oster regulation(异构调控) after the rna Polymerase Binding In some cases RNAP binds the promoters efficiently, but no spontaneous isomerization occurs to lead to the open complex, resulting in no or low transcription Some activators can bind to the closed complex, inducing conformational change in either RNap or DNA promoter, which converts the closed complex to open complex Sand thus promotes the transcription 19
19 4 Targeting transition to the open complex: Allostery regulation (异构调控) after the RNA Polymerase Binding Principles of Transcription Regulation In some cases, RNAP binds the promoters efficiently, but no spontaneous isomerization occurs to lead to the open complex, resulting in no or low transcription. Some activators can bind to the closed complex, inducing conformational change in either RNAP or DNA promoter, which converts the closed complex to open complex and thus promotes the transcription
Allostery regulation RNA polymerase no spontaneous isomerization and thus no transcription activator binding site promoter Fig 16-2 RNA polymerase activator activated level of transcription Allostery is not only a mechanism of gene activation it is also often the way that regulators are controlled by their specific signals
20 Fig 16-2 Allostery regulation Allostery is not only a mechanism of gene activation , it is also often the way that regulators are controlled by their specific signals
5 Targeting promoter escape by some repressors Repressors can work in ways Eas (1)blocking the promoter binding (2)blocking the transition to the open complex (3)blocking promoter escape 21
21 5 Targeting promoter escape by some repressors Principles of Transcription Regulation Repressors can work in ways: (1) blocking the promoter binding. (2) blocking the transition to the open complex. (3) blocking promoter escape