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Chapter 16

Chapter 16. Regulation in Prokaryotes. 25 and 27 October, 2004. Overview. Transcriptional initiation is the most common point to regulate gene expression. Any of the events of initiation, including polymerase binding and open complex formation may be regulated either positively or negatively.

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Chapter 16

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  1. Chapter 16 Regulation in Prokaryotes 25 and 27 October, 2004

  2. Overview • Transcriptional initiation is the most common point to regulate gene expression. • Any of the events of initiation, including polymerase binding and open complex formation may be regulated either positively or negatively. • Regulation is accomplished by sequence-specific DNA binding proteins. • Binding may be promoter proximal or at a distance. • DNA footprinting and mobility shift assays are used to investigate the binding of regulatory proteins. • In the E. coli lac operon, there are both repressors and activators, each of which is allosterically regulated. • Many regulatory systems control a large number of genes and operons, like the catabolite repression and heat shock regulons. • NtrC is regulated by covalent modification, bidds at a distance, and hydrolyzes ATP to pronmote open complex formation. • MerR activates transcription by twisting the promoter. • Riboswitches regulate transcription or translation without protein mediators. • Phage lambda uses alternative regulatory systems to control lytic or lysogenic growth. • Repressor and Cro compete to determine lytic or lysogenic growth, in response to the stability of the CII protein. • Downstream regulation in lambda involves antitermination.

  3. Activators and repressors may regulate binding of polymerase.

  4. Some activators regulate open complex formation.

  5. Cooperative Binding and Transcriptional Regulation at a Distance

  6. The lac operon

  7. lac operon regulation

  8. Control Regions and lac Operator Half-sites

  9. RNA polymerase can form open complexes even in the presence of the LacI protein.

  10. RNA polymerase interacts with promoter and CAP

  11. Helix-turn-helix Interactions with DNA

  12. CAP bends DNA

  13. Activator Bypass

  14. Lac repressor binds as a tetramer

  15. Genetic experiments with partial diploids elucidated the ideas behind regulation of gene expression.

  16. Regulation by Alternative s-Factors

  17. Regulation of GlnA by s-54 and NtrC.

  18. NtrC Acts at a Distance

  19. MerR Regulation

  20. AraC Regulation

  21. Arabinose relaxes loops, and the loops reform in the absence of competitor.

  22. Regulation of the trp operon

  23. Tryptophan Interaction with Trp Repressor

  24. Attenuation

  25. Ribosomal proteins regulate their own translation.

  26. Riboswitches regulate gene expression without regulatory proteins.

  27. Phage lambda

  28. Lambda Genome

  29. Lambda Control Region

  30. Lambda Repressor and Binding Sites

  31. Cooperative Binding

  32. Cooperative and Non-Cooperative Binding

  33. Lambda Regulation

  34. Negative Autoregulation

  35. DNA Looping Between two lac operators

  36. CII Control of the Lytic / Lysogenic Decision

  37. N and Q Antiterminators

  38. int Regulation

  39. Title

  40. Title

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