Prokaryotic Gene Regulation April 22, 2015 Richard D. Howells, PhD MSB E-643

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Presentation transcript:

Prokaryotic Gene Regulation April 22, 2015 Richard D. Howells, PhD MSB E-643

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 132

3 General structure of the tandem arrays of pre-rRNA transcription units

44 RNA is synthesized 5’ to 3’ based on the DNA sequence of the template DNA strand

5 The bacterial RNA polymerase

6 Bacterial RNA Polymerase

7 Inactivation of the prokaryotic RNA polymerase by rifampin - a drug used for treatment of tuberculosis

8 Prokaryotic promoter region: landmark for site of transcription initiation

9 The Lactose (Lac) Operon of Escherichia coli Lac I encodes lac repressor Lac Z encodes  -galactosidase Lac Y encodes lac permease Lac A encodes  -galactoside transacetylase

10 Lactose metabolism in E. coli

11 Transcriptional Regulation of the Lac Operon

18 The Lac Operon Promoter

The lac promoter vs. the promoter consensus sequence 13

14 Structure of cAMP

15 Control of the lac operon by glucose and cAMP

cAMP-CAP (CRP) homodimer (yellow domain interacts with RNA pol) 16

tTThe T 17 The cAMP-CAP complex activates transcription of the lac operon

18 Lac Operon Regulation

Regulation of the trp operon in E. coli 19

Trp repressor homodimer bound to Trp and the trp operator 20

21 Rho-independent termination of transcription

Transcriptional attenuation in the trp operon 22

Transcriptional attenuation in the trp operon 23

Transcriptional attenuation in the trp operon 24

Attenuation in the trp operon 25 (does not cause attenuation)

Leader sequences of other AA operons in E. coli subject to attenuation 26

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