大学课程英汉对照分子生物学导论教学Chapter 3课件
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37 / 68
CAP-cAMP complex
CAP
cAMP
cAMP CAP
DNA
DNA
CAP cAMP
38 / 68
Adenylyl Cyclase (AC)
O
O
O
O-―P―O―P―O―P―O―CH2
A
O
O-
O-
O-
ATP
OH OH
Glucose inhibits the activity of AC.
12 / 68
Catalytic area of RNA polymerase
13 / 68
3.2.3 Transcription Mechanism 3.2.3 转录机理
1. Initiation / 起始 2. Elongation / 延伸 3. Termination / 终止
14 / 68
1. Initiation / 起始
Step 1 Step 2
15 / 68
Initiation / 起始
Step 3 Step 4
16 / 68
2. Elongation / 延伸
Transcription bubble
17 / 68
The polymerization reaction 聚合反应
IID Activator
IID
Chapter 3
IIB IIA IID
IIF IIE
RNA pol II
IIH
TATA box
Chapter 4
6 / 68
3.2 Mechanism of Transcription 3.2 转录机理
7 / 68
3.2.1 Promoters / 启动子
8 / 68
3.3 Regulation of gene expression
in prokaryotes 3.3 原核生物基因表达调控
3.3.1 Coordinate Regulation 3.3.2 The Lac Operon 3.3.3 The Trp Operon 3.3.4 Ara & Gal Operons
45 / 68
Lactose – the inducer Tryptophan – the co-repressor
(b) High tryptophan : transcription is repressed.
RNA polymerase cannot bind to the promoter
Lactose
Inducer 诱导物
Promoter Operator Leader -attenuator trpE
trpD
Aporepressor dimer
Repressor dimer
Co-repressor 辅阻遏物
Tryptophan
46 / 68
The Trp Operon: No positive regulation
33 / 68
Regulated Expression of Lactose Metabolizing Genes
乳糖代谢基因表达调控
1. Negative Regulation – the lac Repressor 负调控──lac阻遏蛋白
2. Positive Regulation – CAP 正调控──CAP
-35 box
-10 box
+1
9 / 68
Consensus sequence / 共有序列
Consensus sequence: a generalized sequence from which most actual sequences differ very little or not at all. （共有序列：一种普遍的序列， 大多数实际的序列与它相差很小或完全相同。）
Low tryptophan level: Transcription occurs
44 / 68
lac repressor vs. trp repressor
Repressor
Low lactose level
(b) High tryptophan : transcription is repressed.
Chapter 3 / 第3章
Chapter 3 Transcription in Prokaryotes: Mechanism and Regulation 3.1 Why Use an RNA Intermediate?
第3章 原核生物转录： 机理与调控 3.1 为什么使用RNA
作为中间物？
3.2 Mechanism of Transcription 3.3 Regulation of Gene Expression
AC
O—CH2
A
O
cAMP
O P——O
OH
O
39 / 68
CAP – “The accelerator” lac repressor – “The brake”
Brake 刹车
Accelerator 加速器
40 / 68
3.3.3 The Trp Operon / 色氨酸操纵子
Promoter Operator Leader-attenuator trpE
When to use lactose / 何时利用乳糖
Glucose + Lactose +
Glucose – Lactose –
Glucose – Lactose +
E. coli: “I will use lactose only when there is no glucose and there is lactose.”
半乳糖
葡萄糖
E. coli: “This is my favorite!”
31 / 68
How to use lactose / 如何利用乳糖
E. coli: “I need lactose permease, β-galactosidase, and transacetylase.”
32 / 68
Protein 3
29 / 68
3.3.2 The lac Operon / 乳糖操纵子
Promoter Operator lacZ lacY lacA
The lac operon
30 / 68
1. The Conditions of lactose Metabolism 1. 乳糖代谢的条件
乳糖
20 / 68
Intrinsic termination / 内在型终止
21 / 68
Base pair / 碱基对
22 / 68
-dependent termination / 依赖型终止
23 / 68
Rho proteins
X-Ray Crystal Structure Of Rho protein [MMDB ID:24381] 24 / 68
3.3.1 协同调控 3.3.2 乳糖操纵子 3.3.3 色氨酸操纵子 3.3.4 阿拉伯糖与
半乳糖操纵子
25 / 68
Regulation of gene expression 基因表达调控
Condition A
26 / 68
Regulation of gene expression 基因表达调控
47 / 68
2. Attenuation / 衰减作用
Attenuator: “STOP!”
Not all transcription is repressed.
48 / 68
The leader-attenuator region 前导子-衰减子区域
Promoter Operator Leader-attenuator trpE trpD trpC trpB trpA
in Prokaryotes 3.4 Experiments
3.2 转录机理 3.3 原核生物基因
表达调控 3.4 实验研究
1 / 68
3.1 Why Use an RNA intermediate? 3.1 为什么使用RNA作为中间物？
2 / 68
Chromosomes are large and complex
lacA
CH2OH
Байду номын сангаас
OH
O
OH
O
CH2OH O OH
OH
OH
Lactose
OH
42 / 68
1. Negative Regulation – High Trp level
High tryptophan level: No transcription
43 / 68
Negative Regulation – low Trp level
−10 box and −35 box
Transcription start site
5’
5’
3’
3’
-35 box
+1 -10 box
Coding region
Promoter
CCAGGCTTTACACTT - - -CGTATGTTGTGTGGAATT CTTTTTGATGCAATT - - -ACTATAATAGACAGGGTA GGCGGTGTTGACATA - - -GTGATACTGAGCACATCA
52 / 68
When tryptophan level is high …
53 / 68
3.3.4 Ara and Gal Operons 3.3.4 阿拉伯糖操纵子与半乳糖操纵子
trpD trpC trpB trpA
CH
CH N H
COO – +H3N C H
CH3
Tryptophan
COO –
+H3N C H
CH2
C
CH N H
Promoter Operator lacZ
CH2OH
OH
O OH
OH
+
OH
Galactose
CH2OH O OH
OH OH
OH
Glucose
lacY
34 / 68
2. Negative Regulation – the lac Repressor 负调控──lac阻遏蛋白
35 / 68
Negative Regulation – the lac Repressor 负调控──lac阻遏蛋白
36 / 68
3. Positive Regulation – CAP 正调控──CAP
RNA synthesis: 5’ → 3’
18 / 68
Proofreading / 校正
U Remove U Add C C
19 / 68
3. Termination / 终止
Intrinsic termination 内在型终止 ρ-dependent termination ρ依赖型终止
RNA polymerase cannot bind to the promoter
Promoter Operator Leader -attenuator trpE
trpD
Aporepressor dimer
Repressor dimer
High tryptophan level
Tryptophan
-35 box
-10 box
+1
10 / 68
3.2.2 RNA Polymerase / RNA聚合酶
11 / 68
Core enzyme vs. Holoenzyme
Holoenzyme starts transcription at promoters
Core enzyme starts transcription at random
Condition B
27 / 68
3.3.1 Coordinate Regulation 协同调控
operon
Operator 操纵基因
28 / 68
Polycistronic mRNA 多顺反子mRNA
Polycistronic mRNA
Translation
Protein 1
Protein 2
Region 1
Region 2
Region 3
Region 4
49 / 68
The leader-attenuator RNA
50 / 68
The coupled transcription-translation 偶联转录-翻译作用
51 / 68
When tryptophan level is low …
DNA
Protein
Ribosome
Low efficiency !
3 / 68
DNA must be stable
Age: 15
Age: 45 Age: 75
No change !
No change !
4 / 68
One mRNAmany proteins
5 / 68
More opportunities for regulation
Consensus sequences
TTGACA
TATAAT
CCAGGCTTTACACTT - - -CGTATGTTGTGTGGAATT CTTTTTGATGCAATT - - -ACTATAATAGACAGGGTA GGCGGTGTTGACATA - - -GTGATACTGAGCACATCA
CAP-cAMP complex
CAP
cAMP
cAMP CAP
DNA
DNA
CAP cAMP
38 / 68
Adenylyl Cyclase (AC)
O
O
O
O-―P―O―P―O―P―O―CH2
A
O
O-
O-
O-
ATP
OH OH
Glucose inhibits the activity of AC.
12 / 68
Catalytic area of RNA polymerase
13 / 68
3.2.3 Transcription Mechanism 3.2.3 转录机理
1. Initiation / 起始 2. Elongation / 延伸 3. Termination / 终止
14 / 68
1. Initiation / 起始
Step 1 Step 2
15 / 68
Initiation / 起始
Step 3 Step 4
16 / 68
2. Elongation / 延伸
Transcription bubble
17 / 68
The polymerization reaction 聚合反应
IID Activator
IID
Chapter 3
IIB IIA IID
IIF IIE
RNA pol II
IIH
TATA box
Chapter 4
6 / 68
3.2 Mechanism of Transcription 3.2 转录机理
7 / 68
3.2.1 Promoters / 启动子
8 / 68
3.3 Regulation of gene expression
in prokaryotes 3.3 原核生物基因表达调控
3.3.1 Coordinate Regulation 3.3.2 The Lac Operon 3.3.3 The Trp Operon 3.3.4 Ara & Gal Operons
45 / 68
Lactose – the inducer Tryptophan – the co-repressor
(b) High tryptophan : transcription is repressed.
RNA polymerase cannot bind to the promoter
Lactose
Inducer 诱导物
Promoter Operator Leader -attenuator trpE
trpD
Aporepressor dimer
Repressor dimer
Co-repressor 辅阻遏物
Tryptophan
46 / 68
The Trp Operon: No positive regulation
33 / 68
Regulated Expression of Lactose Metabolizing Genes
乳糖代谢基因表达调控
1. Negative Regulation – the lac Repressor 负调控──lac阻遏蛋白
2. Positive Regulation – CAP 正调控──CAP
-35 box
-10 box
+1
9 / 68
Consensus sequence / 共有序列
Consensus sequence: a generalized sequence from which most actual sequences differ very little or not at all. （共有序列：一种普遍的序列， 大多数实际的序列与它相差很小或完全相同。）
Low tryptophan level: Transcription occurs
44 / 68
lac repressor vs. trp repressor
Repressor
Low lactose level
(b) High tryptophan : transcription is repressed.
Chapter 3 / 第3章
Chapter 3 Transcription in Prokaryotes: Mechanism and Regulation 3.1 Why Use an RNA Intermediate?
第3章 原核生物转录： 机理与调控 3.1 为什么使用RNA
作为中间物？
3.2 Mechanism of Transcription 3.3 Regulation of Gene Expression
AC
O—CH2
A
O
cAMP
O P——O
OH
O
39 / 68
CAP – “The accelerator” lac repressor – “The brake”
Brake 刹车
Accelerator 加速器
40 / 68
3.3.3 The Trp Operon / 色氨酸操纵子
Promoter Operator Leader-attenuator trpE
When to use lactose / 何时利用乳糖
Glucose + Lactose +
Glucose – Lactose –
Glucose – Lactose +
E. coli: “I will use lactose only when there is no glucose and there is lactose.”
半乳糖
葡萄糖
E. coli: “This is my favorite!”
31 / 68
How to use lactose / 如何利用乳糖
E. coli: “I need lactose permease, β-galactosidase, and transacetylase.”
32 / 68
Protein 3
29 / 68
3.3.2 The lac Operon / 乳糖操纵子
Promoter Operator lacZ lacY lacA
The lac operon
30 / 68
1. The Conditions of lactose Metabolism 1. 乳糖代谢的条件
乳糖
20 / 68
Intrinsic termination / 内在型终止
21 / 68
Base pair / 碱基对
22 / 68
-dependent termination / 依赖型终止
23 / 68
Rho proteins
X-Ray Crystal Structure Of Rho protein [MMDB ID:24381] 24 / 68
3.3.1 协同调控 3.3.2 乳糖操纵子 3.3.3 色氨酸操纵子 3.3.4 阿拉伯糖与
半乳糖操纵子
25 / 68
Regulation of gene expression 基因表达调控
Condition A
26 / 68
Regulation of gene expression 基因表达调控
47 / 68
2. Attenuation / 衰减作用
Attenuator: “STOP!”
Not all transcription is repressed.
48 / 68
The leader-attenuator region 前导子-衰减子区域
Promoter Operator Leader-attenuator trpE trpD trpC trpB trpA
in Prokaryotes 3.4 Experiments
3.2 转录机理 3.3 原核生物基因
表达调控 3.4 实验研究
1 / 68
3.1 Why Use an RNA intermediate? 3.1 为什么使用RNA作为中间物？
2 / 68
Chromosomes are large and complex
lacA
CH2OH
Байду номын сангаас
OH
O
OH
O
CH2OH O OH
OH
OH
Lactose
OH
42 / 68
1. Negative Regulation – High Trp level
High tryptophan level: No transcription
43 / 68
Negative Regulation – low Trp level
−10 box and −35 box
Transcription start site
5’
5’
3’
3’
-35 box
+1 -10 box
Coding region
Promoter
CCAGGCTTTACACTT - - -CGTATGTTGTGTGGAATT CTTTTTGATGCAATT - - -ACTATAATAGACAGGGTA GGCGGTGTTGACATA - - -GTGATACTGAGCACATCA
52 / 68
When tryptophan level is high …
53 / 68
3.3.4 Ara and Gal Operons 3.3.4 阿拉伯糖操纵子与半乳糖操纵子
trpD trpC trpB trpA
CH
CH N H
COO – +H3N C H
CH3
Tryptophan
COO –
+H3N C H
CH2
C
CH N H
Promoter Operator lacZ
CH2OH
OH
O OH
OH
+
OH
Galactose
CH2OH O OH
OH OH
OH
Glucose
lacY
34 / 68
2. Negative Regulation – the lac Repressor 负调控──lac阻遏蛋白
35 / 68
Negative Regulation – the lac Repressor 负调控──lac阻遏蛋白
36 / 68
3. Positive Regulation – CAP 正调控──CAP
RNA synthesis: 5’ → 3’
18 / 68
Proofreading / 校正
U Remove U Add C C
19 / 68
3. Termination / 终止
Intrinsic termination 内在型终止 ρ-dependent termination ρ依赖型终止
RNA polymerase cannot bind to the promoter
Promoter Operator Leader -attenuator trpE
trpD
Aporepressor dimer
Repressor dimer
High tryptophan level
Tryptophan
-35 box
-10 box
+1
10 / 68
3.2.2 RNA Polymerase / RNA聚合酶
11 / 68
Core enzyme vs. Holoenzyme
Holoenzyme starts transcription at promoters
Core enzyme starts transcription at random
Condition B
27 / 68
3.3.1 Coordinate Regulation 协同调控
operon
Operator 操纵基因
28 / 68
Polycistronic mRNA 多顺反子mRNA
Polycistronic mRNA
Translation
Protein 1
Protein 2
Region 1
Region 2
Region 3
Region 4
49 / 68
The leader-attenuator RNA
50 / 68
The coupled transcription-translation 偶联转录-翻译作用
51 / 68
When tryptophan level is low …
DNA
Protein
Ribosome
Low efficiency !
3 / 68
DNA must be stable
Age: 15
Age: 45 Age: 75
No change !
No change !
4 / 68
One mRNAmany proteins
5 / 68
More opportunities for regulation
Consensus sequences
TTGACA
TATAAT
CCAGGCTTTACACTT - - -CGTATGTTGTGTGGAATT CTTTTTGATGCAATT - - -ACTATAATAGACAGGGTA GGCGGTGTTGACATA - - -GTGATACTGAGCACATCA