Regulation of Transcription Initiation Chapter 10 Regulation of Transcription Initiation Copyright (c) by W. H. Freeman and Company

10.1 Bacterial gene control: the Jacob-Monod model Figure 10-2 Copyright (c) by W. H. Freeman and Company

10.1 Experimental evidence for cis-acting DNA sequences Figure 10-3 Copyright (c) by W. H. Freeman and Company

10.1 Experimental evidence for trans-acting genes/proteins Figure 10-4 Copyright (c) by W. H. Freeman and Company

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 Copyright (c) by W. H. Freeman and Company

10.2 DNase I footprinting assays identify protein-DNA interactions Figure 10-6 Copyright (c) by W. H. Freeman and Company

10.2 Gel-shift assays identify protein-DNA interactions Figure 10-7 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 10.2 The footprint of RNA polymerase and lac repressor on the lac control region Figure 10-8 Copyright (c) by W. H. Freeman and Company

10.2 The lac control region contains three critical cis-acting sites Figure 10-9 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 10.2 RNA polymerase binds to specific promoter sequences to initiate transcription Each subunit has a specific function Figure 10-10 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 10.2 Differences in E. coli promoter sequences affect the frequency of transcription initiation Copyright (c) by W. H. Freeman and Company Figure 10-11

10.2 Most operator sequences are short inverted repeats The lac operator Figure 10-12 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 10.2 Most bacterial repressors are dimers containing  helices that insert into adjacent major grooves of operator DNA Figure 10-13 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 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 Copyright (c) by W. H. Freeman and Company

10.2 Positive control of the lac operon is exerted by cAMP-CAP CAP = catabolite activator protein Figure 10-16 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 10.2 Cooperative binding of cAMP-CAP and RNA polymerase to the lac contol region activates transcription Figure 10-17 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 10.2 Transcription from some promoters is initiated by alternative sigma () factors Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 10.2 Activation of 54-containing RNA polymerase at glnA promotor by NtrC Figure 10-19 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 10.2 Visualization of DNA looping and interaction of bound NtrC and 54- polymerase Figure 10-20 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 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 Copyright (c) by W. H. Freeman and Company