dna recognition in procaryotes by helix-turn-helix motifs
TRANSCRIPT
DNA Recognition in Procaryotes DNA Recognition in Procaryotes by Helix-Turn-Helix Motifsby Helix-Turn-Helix Motifs
10.2 Most bacterial repressors are dimers 10.2 Most bacterial repressors are dimers containing containing helices that insert into adjacent helices that insert into adjacent
major grooves of operator DNA major grooves of operator DNA
Figure 10-13
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By itself, an operon is on and RNA polymerase can bind to the promoter and transcribe the genes.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 18.20a
However, if a repressor protein, a product of a regulatory However, if a repressor protein, a product of a regulatory gene, binds to the operator, it can prevent transcription of gene, binds to the operator, it can prevent transcription of the operon’s genes.the operon’s genes.– Each repressor protein recognizes and binds only to the Each repressor protein recognizes and binds only to the
operator of a certain operon.operator of a certain operon.– Regulatory genes are transcribed at low rates Regulatory genes are transcribed at low rates
continuously. continuously.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 18.20b
10.2 Ligand-induced conformational ch10.2 Ligand-induced conformational changes alter affinity of many repressors fanges alter affinity of many repressors f
or DNAor DNA
Figure 10-14
Tryptophan binding induces a conformational change in the trp aporepressor
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10.2 DNase I footprinting assays ident10.2 DNase I footprinting assays identify protein-DNA interactionsify protein-DNA interactions
Figure 10-6
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10.2 Gel-shift assays identify protein-10.2 Gel-shift assays identify protein-DNA interactionsDNA interactions
Figure 10-7
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10.2 The footprint of RNA polymerase 10.2 The footprint of RNA polymerase and and laclac repressor on the repressor on the laclac control re control re
giongion
Figure 10-8
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10.2 The lac control region contains t10.2 The lac control region contains three critical cis-acting siteshree critical cis-acting sites
Figure 10-9
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10.2 Positive control of the 10.2 Positive control of the laclac operon operon is exerted by cAMP-CAPis exerted by cAMP-CAP
Figure 10-16
CAP = catabolite activator protein
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10.2 A space-filling model of cAMP-CA10.2 A space-filling model of cAMP-CAP bound to P bound to laclac promoter DNA promoter DNA
Figure 10-18
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10.2 Cooperative binding of cAMP-CAP and 10.2 Cooperative binding of cAMP-CAP and RNA polymerase to the RNA polymerase to the laclac contol region ac contol region ac
tivates transcriptiontivates transcription
Figure 10-17
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