1. Regulation of Transcription Initiation
Chapter 10
Regulation of Transcription Initiation
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2. 10.1 Bacterial gene control: the Jacob-Monod model
Figure 10-2
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3. 10.1 Experimental evidence for cis-acting DNA sequences
Figure 10-3
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4. 10.1 Experimental evidence for trans-acting genes/proteins
Figure 10-4
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5. 10.2 Bacterial transcription initiation
RNA polymerase initiates transcription of most genes at a unique DNA position lying upstream of the coding sequence
The base pair where transcription initiates is termed the transcription-initiation site or start site
By convention, the transcription-initiation site in the DNA sequence is designated +1, and base pairs extending in the direction of transcription (downstream) are assigned positive numbers which those extending in the opposite direction (upstream) are assigned negative numbers
Various proteins (RNA polymerase, activators, repressors) interact with DNA at or near the promoter to regulate transcription initiation
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6. 10.2 DNase I footprinting assays identify protein-DNA interactions
Figure 10-6
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7. 10.2 Gel-shift assays identify protein-DNA interactions
Figure 10-7
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10.2 The footprint of RNA polymerase and lac repressor on the lac control region
Figure 10-8
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9. 10.2 The lac control region contains three critical cis-acting sites
Figure 10-9
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10.2 RNA polymerase binds to specific promoter sequences to initiate transcription
Each subunit has a specific function
Figure 10-10
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10.2 Differences in E. coli promoter sequences affect the frequency of transcription initiation
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Figure 10-11

12. 10.2 Most operator sequences are short inverted repeats
The lac operator
Figure 10-12
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10.2 Most bacterial repressors are dimers containing  helices that insert into adjacent major grooves of operator DNA
Figure 10-13
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10.2 Ligand-induced conformational changes alter affinity of many repressors for DNA
Tryptophan binding induces a conformational change in the trp aporepressor
Figure 10-14
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15. 10.2 Positive control of the lac operon is exerted by cAMP-CAP
CAP = catabolite
activator protein
Figure 10-16
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10.2 Cooperative binding of cAMP-CAP and RNA polymerase to the lac contol region activates transcription
Figure 10-17
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10.2 Transcription from some promoters is initiated by alternative sigma () factors
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10.2 Activation of 54-containing RNA polymerase at glnA promotor by NtrC
Figure 10-19
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10.2 Visualization of DNA looping and interaction of bound NtrC and 54- polymerase
Figure 10-20
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10.2 Many bacterial responses are controlled by two-component regulatory systems
The PhoR/PhoB two-component regulatory system in E. coli
Figure 10-21
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