Transcript Chapter 4
10.3 Eukaryotic gene control: purposes and general principles Unlike bacterial cells and most single cell eukaryotes, cells in multicelular organisms have relatively few genes that are reversibly regulated by environmental conditions However, gene control in multicellular organisms is important for development and differentiation, and is generally not reversible Copyright (c) by W. H. Freeman and Company
10.3 Many genes in higher eukaryotes are regulated by controlling their transcription
The nascent chain (run-on) assay allows measurement of the rate of transcription of a given gene
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Figure 10-22
10.3 Differential synthesis of 12 mRNAs encoding liver-specific genes Copyright (c) by W. H. Freeman and Company
Figure 10-23
10.3 Regulatory elements in eukaryotic DNA often are many kilobases from start sites The basic principles that control transcription in bacteria also apply to eukaryotic organisms: transcription is initiated at a specific base pair and is controlled by the binding of trans acting proteins (transcription factors) to cis-acting regulatory DNA sequences However, eukaryotic cis-acting elements are often much further from the promoter they regulate, and transcription from a single promoter may be regulated by binding of multiple transcription factors to alternative control elements Transcription control sequences can be identified by analysis of a 5 -deletion series Copyright (c) by W. H. Freeman and Company
10.3 Construction and analysis of a 5 -deletion series Copyright (c) by W. H. Freeman and Company
Figure 10-24
10.3 Analysis of labeled nascent transcripts allows mapping of the transcription-initiation site Copyright (c) by W. H. Freeman and Company
Figure 10-28
10.3 RNA polymerase II initiates transcription at DNA sequences corresponding to the 5 cap of mRNAs “Runs off” “Runs off” “Runs off” Copyright (c) by W. H. Freeman and Company
Figure 10-29
10.4 The TATA box is a highly conserved promoter in eukaryotic DNA
Alternative promoters in eukaryotes include initiators and CpG islands
5’-YYA +1 N-T/A-YYY-3’ (Y=C/T)
Figure 10-30
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10.4 Identification of transcription-control elements with linker mutants Copyright (c) by W. H. Freeman and Company
Figure 10-31
10.4 Promoter-proximal elements help regulate eukaryotic genes Copyright (c) by W. H. Freeman and Company
Figure 10-32
10.4 Transcription by RNA polymerase II often is stimulated by distant enhancer sites
Identification of the SV40 enhancer region
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Figure 10-33
10.4 Most eukaryotic genes are regulated by multiple transcription control mechanisms Copyright (c) by W. H. Freeman and Company
Figure 10-34
10.5 Transcription factors may be identified by biochemical techniques Copyright (c) by W. H. Freeman and Company
Figure 10-35
10.5 In vivo assay for transcription factor activity Copyright (c) by W. H. Freeman and Company
Figure 10-37
10.5 A series of
Gal4
deletion mutants demonstrated that transcription factors are composed of separable DNA-binding and activation domains Copyright (c) by W. H. Freeman and Company
Figure 10-38
10.5 Transcriptional activators are modular proteins composed of distinct functional domains Copyright (c) by W. H. Freeman and Company
Figure 10-39
10.5 DNA-binding domains can be classified into numerous structural types Homeodomain proteins Zinc-finger proteins Winged-helix (forkhead) proteins Leucine-zipper proteins Helix-loop-helix proteins Copyright (c) by W. H. Freeman and Company
10.5 Homeodomain from Engrailed protein interacting with its specific DNA recognition site Copyright (c) by W. H. Freeman and Company
Figure 10-40
10.5 Interactions of C 2 H 2 domains with DNA and C 4 zinc-finger Copyright (c) by W. H. Freeman and Company
Figure 10-41
10.5 Interaction between a C 6 protein (Gal4) and DNA zinc-finger Copyright (c) by W. H. Freeman and Company
Figure 10-42
10.5 Interaction of a homodimeric leucine-zipper protein and DNA dimerização assegurada pela interacção dos a.a. Hidrofóbicos (ex:leucina) espaçados regularmente
Figure 10-43
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10.5 Interaction of a helix-loop-helix in a homodimeric protein and DNA Copyright (c) by W. H. Freeman and Company
Figure 10-44
10.5 Heterodimeric transcriptional factors increase gene-control options Copyright (c) by W. H. Freeman and Company
Figure 10-45
10.5 Activation domains exhibit considerable structural diversity
Figure 10-46
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Figure 10-47
10.5 Multiprotein complexes form on enhancers Copyright (c) by W. H. Freeman and Company
Figure 10-48
10.5 Many repressors are the functional converse of activators Eukaryotic transcription is regulated by repressors as well as activators Repressor-binding sites can be identified and repressors purified by the same techniques used for activators Many eukaryotic repressors have two domains: a DNA binding domain and a repressor domain Copyright (c) by W. H. Freeman and Company
10.6 RNA polymerase II transcription initiation complex Initiation by Pol II requires general transcription factors, which position Pol II at initiation sites and are required for transcription of most genes transcribed by this polymerase General transcription factors are multimeric and highly conserved Proteins comprising the Pol II transcription-initiation complex assemble in a specific order in vitro but most of the proteins may combine to form a holoenzyme complex in vivo Copyright (c) by W. H. Freeman and Company
10.6 Stepwise assembly of Pol II transcription-initiation complex in vitro Copyright (c) by W. H. Freeman and Company
Figure 10-50
10.6 The conserved C-terminal domain of TBP binds to TATA-box DNA
TBP is a subunit of TFIID
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Figure 10-51
10.6 Structural model of the complex of promoter DNA, TBP, TFIIB, and Pol II Copyright (c) by W. H. Freeman and Company
Figure 10-53
10.7 Activators stimulate the highly cooperative assembly of initiation complexes
Binding sites for activators that control transcription of the mouse
TTR
gene
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Figure 10-60
10.7 Model for cooperative assembly of an activated transcription-initiation complex in the
TTR
promoter Copyright (c) by W. H. Freeman and Company
Figure 10-61
10.7 Repressors interfere directly with transcription initiation in several ways Copyright (c) by W. H. Freeman and Company
Figure 10-62
10.7 Lipid-soluble hormones control the activities of nuclear receptors Copyright (c) by W. H. Freeman and Company
Figure 10-63
10.7 Domain structure of nuclear receptors Copyright (c) by W. H. Freeman and Company
Figure 10-64
10.7 Response elements are DNA sites that bind several major nuclear receptors Copyright (c) by W. H. Freeman and Company
Figure 10-65
10.7 Model of hormone-dependent gene activation by the glucocorticoid receptor
Figure 10-67
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10.7 Polypeptide hormones signal phosphorylation of some transcription factors
Model of IFN
-mediated gene activation by phosphorylation and dimerization of Stat1
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Figure 10-68
10.8 Transcription initiation by Pol I and Pol III is analogous to that by Pol II Copyright (c) by W. H. Freeman and Company
Figure 10-69
10.8 Other transcription systems T7 and related bacteriophages express monomeric, largely unregulated RNA polymerases Mitochondrial DNA is transcribed by RNA polymerases with similarities to bacteriophage and bacterial enzymes Transcription of chloroplast DNA resembles bacterial transcription Transcription by archaeans is closer to eukaryotic than to bacterial transcription Copyright (c) by W. H. Freeman and Company