prokaryotic gene regulation april 22, 2015 richard d. howells, phd msb e-643...
TRANSCRIPT
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Objectives
During this presentation, you may catch up on needed sleep recall the process of transcription appreciate how the lac and trp operons are
regulated in bacteria
Lecture 13 2
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General structure of the tandem arrays of pre-rRNA transcription units
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RNA is synthesized 5’ to 3’ based on the DNA sequence of the template DNA strand
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The bacterial RNA polymerase
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Bacterial RNA Polymerase
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Inactivation of theprokaryotic RNA
polymerase byrifampin - a
drug used for treatment of tuberculosis
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Prokaryotic promoter region: landmark for site of transcription initiation
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The Lactose (Lac) Operon of Escherichia coli
Lac I encodes lac repressor
Lac Z encodes b-galactosidase
Lac Y encodes lac permease
Lac A encodes b-galactoside transacetylase
1920-2013
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Lactose metabolism
in E. coli
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Transcriptional Regulation of the Lac Operon
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The Lac Operon Promoter
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The lac promoter vs. the promoter consensus sequence
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Structure of cAMP
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Control of the lac operon by glucose and cAMP
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cAMP-CAP (CRP) homodimer (yellow domain interacts with RNA pol)
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tTThe T
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The cAMP-CAP complex activates transcription
of the lac operon
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Lac Operon Regulation
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Regulation of the trp operon in E. coli
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Trp repressor homodimer bound to Trp and the trp operator
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Rho-independenttermination oftranscription
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Transcriptional attenuation in the trp operon
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Transcriptional attenuation in the trp operon
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Transcriptional attenuation in the trp operon
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Attenuation in the trp operon
25(does not cause attenuation)
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Leader sequences of other AA operons in E. coli subject to attenuation
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