上海交通大学：《微生物学 Microbiology》课程教学资源（双语课件）Lecture 8.2 Metabolic Regulation（Regulation of Gene Expression）

上游充通大 SHANGHAI JIAO TONG UNIVERSITY 1896 1920 1987 2006 Lecture 8-2 Metabolic Regulation (Regulation of gene expression) CHAPTER 8 in BROCK BIOLOGY OF MICROORGANISMS Chen Feng School of Life Science and Technology Shanghai Jiao Tong University Email:cf2001@situ.edu.cn http://micro.sjtu.edu.cn

1896 1920 1987 2006 Lecture 8-2 Metabolic Regulation (Regulation of gene expression) Chen Feng School of Life Science and Technology Shanghai Jiao Tong University Email: cf2001@sjtu.edu.cn http://micro.sjtu.edu.cn CHAPTER 8 in BROCK BIOLOGY OF MICROORGANISMS

上游充通大 SHANGHAI JIAO TONG UNIVERSITY 1896 1920 1987 2006 IlI.DNA-Binding Proteins and Regulation of Transcription by Negative and Positive Control (Transcriptional level regulation) DNA结合蛋白与转录水平的调控

1896 1920 1987 2006 III. DNA-Binding Proteins and Regulation of Transcription by Negative and Positive Control (Transcriptional level regulation) DNA结合蛋白与转录水平的调控

上浒充通大淫 SHANGHAI JIAO TONG UNIVERSITY 8.5 Negative control of transcription: Repression and Induction转录的负调控 Repression阻遏 End product of a pathway inhibits transcription of genes for enzymes in its synthesis Induction诱导 Gene of an enzyme will be transcribed only when its substrate is present Chen Feng,Shanghai Jiao Tong University

Chen Feng, Shanghai Jiao Tong University 8.5 Negative control of transcription: Repression and Induction转录的负调控 Repression阻遏 • End product of a pathway inhibits transcription of genes for enzymes in its synthesis Induction诱导 • Gene of an enzyme will be transcribed only when its substrate is present

上游充通大￥ SHANGHAI JIAO TONG UNIVERSITY Example of Repression of Transcription阻遏例子 Repression Enzymes involved in formation of arginine Cell number. Total are synthesized only protein when arginine is absent from the medium Arginine added External arginine represses the synthesis Arginine biosynthesis of these enzymes. enzymes Time 2012 Pearson Education,inc

Chen Feng, Shanghai Jiao Tong University Example of Repression of Transcription阻遏例子 Enzymes involved in formation of arginine are synthesized only when arginine is absent from the medium External arginine represses the synthesis of these enzymes

上降充通大粤 SHANGHAI JIAO TONG UNIVERSITY xample of Induction of Transcription诱导例子 Induction Total protein If lactose is absent from the medium the enzyme is not synthesized,but Cell number synthesis begins almost immediately after lactose B-Galacto- is added. sidase Lactose added Time 2012 Pearson Education,Inc

Chen Feng, Shanghai Jiao Tong University Example of Induction of Transcription诱导例子 If lactose is absent from the medium the enzyme is not synthesized, but synthesis begins almost immediately after lactose is added

上降充通大粤 .5.1 Mechanism of Repression:Repressor and corepressor阻遏物与共阻遏物 arg Promoter)arg Operator argC argB argH RNA polymerase Transcription proceeds (a) Repressor 2012 Pearson Education,Inc. Transcription of the operon occurs because the repressor is unable to bind to the operator..阻遏蛋白不能与操纵基因结 合，所以操纵子可转录 Chen Feng,Shanghai Jiao Tong University

Chen Feng, Shanghai Jiao Tong University 8.5.1 Mechanism of Repression: Repressor and corepressor 阻遏物与共阻遏物 Transcription of the operon occurs because the repressor is unable to bind to the operator.阻遏蛋白不能与操纵基因结 合,所以操纵子可转录

arg Promoter)arg Operator argC argB argH RNA Corepressor polymerase (arginine) Transcription blocked (b) Repressor 2012 Pearson Education,Inc. (b)After a corepressor binds to the repressor,the repressor binds to the operator and blocks transcription; 共阻遏物的作用 In argCBH operon the repressor would be the arginine repressor and the corepressor would be arginine

(b) After a corepressor binds to the repressor, the repressor binds to the operator and blocks transcription; 共阻遏物的作用 In argCBH operon the repressor would be the arginine repressor and the corepressor would be arginine

上游充通大淫 SHANGHAI JIAO TONG UNIVERSITY arg Promoterarg Operator argc argB argH RNA polymerase →→→ Transcription proceeds (a) Repressor arg Promoter)arg Operator argc argB argH RNA Corepressor polymerase (arginine) Transcription blocked (b) Repressor 2012 Pearson Education.Inc. The process of enzyme repression

The process of enzyme repression Chen Feng, Shanghai Jiao Tong University

上降充通大粤 HANGHAI JIAO TONG UNIVERSITY 5.2 Mechanism of Induction:Inducer and repressor诱导物与阻遏蛋白 lac Promoter lac Operator lacZ lacY lacA RNA polymerase U Transcription blocked Repressor (a) 2012 Pearson Education.Inc. A repressor protein binds to the operator region and blocks the action of RNA polymerase.阻遏蛋白可与操纵基 因结合而阻断RNA聚合酶的行为 Chen Feng,Shanghai Jiao Tong University

Chen Feng, Shanghai Jiao Tong University 8.5.2 Mechanism of Induction: Inducer and repressor 诱导物与阻遏蛋白 A repressor protein binds to the operator region and blocks the action of RNA polymerase.阻遏蛋白可与操纵基 因结合而阻断RNA聚合酶的行为

FLASH 1:lac operon lac Promoter lac Operator lacZ lacY lacA RNA polymerase Transcription proceeds Repressor (b) Inducer 2012 Pearson Education,Inc. (b)An inducer binds to the repressor and inactivates it so that it no longer can bind to the operator. Transcription by RNA polymerase occurs.诱导物的作用 In lac operon the repressor would be the lac repressor, and the inducer would be allolactose异乳糖

(b) An inducer binds to the repressor and inactivates it so that it no longer can bind to the operator. Transcription by RNA polymerase occurs. 诱导物的作用 In lac operon the repressor would be the lac repressor, and the inducer would be allolactose异乳糖. FLASH 1: lac operon