1. The lactose (lac) operon - an example for prokaryotic gene regulation

2. 19. LCT and MCM 6 genes Breakdown of lactose in human Breakdown of lactose in human

3. Nobel prize for the discovery of lac operon - 1965 - 1965 Francois Jacob Jacques Monod Pasteur Institute, Paris, France 1.

4. DNA lacZ repressor CAP site RNA pol operator structural genes terminator lacI O lacY lacA C E promoter P Cytoplasm cell wall outer world promoter Structural genes DNA T catabolit activator protein binding site E. coli DNA binding site operon The structure of lac operon 2.

5. Structure lac operon 3.

6. DNA lacZ lacI O lacY lacA C E P repressor CAP site entry site operator structural genes terminator T pol rep Repression rep: repressor pol: RNA polymerase 4.

7. DNA lacZ lacI O lacY lacA C E P rep lactose galactose glucose repressor CAP site entry site operator structural genes terminator T rep: repressor pol: RNA polymerase 5. InductionInduction

8. DNA lacZ lacI O lacY lacA C E P trans- acetylase permease rep b-gal repressor CAP site entry site operator structural genes terminator T pol rep: repressor pol: RNA polymerase 5. InductionInduction

9. DNA lacZ lacI O lacY lacA C E P CAP cAMP No glucose repressor CAP site entry site operator structural genes terminator T CAP: catabolite activator protein 6. ActivationActivation

10. DNA lacZ lacI O lacY lacA C E P cAMP No glucose repressor CAP site entry site operator structural genes terminator T CAP pol 6. ActivationActivation

11. DNA lacZ lacI O lacY lacA C E P CAP pol b-galpermease trans- acetylase repressor CAP site entry site operator structural genes terminator T 6. ActivationActivation

12. DNA lacZ lacI O lacY lacA C E P No cAMP Glucose is present repressor CAP site entry site operator structural genes terminator T 6. CAP pol catabolite repression (endproduct inhibition) ActivationActivation

13. DNA lacZ lacI O lacY lacA C E P CAP Combined regulation pol cAMP glucose lactose rep b-galpermease ATP adenylate cyclase lactose allolactose (inductor!) Glucose - Lactose + trans- acetylase Structure and operation of lac operon repressor CAP site entry site operator structural genes terminator T 7. adenylate cyclase cyclic AMP

14. DNA lacI O lacY lacA C E P CAP cAMP No glucose lacZ pol rep Glucose - Lactose + repressor CAP site entry site operator structural genes terminator T Mutant beta-gal 8.

15. DNA lacI O lacY lacA C E P CAP permease lacZ pol lactose b-gal* Glucose - Lactose + trans- acetylase repressor CAP site entry site operator structural genes terminator T 8. Mutant beta-gal

16. DNA lacZ lacI O lacY lacA C E P CAP pol rep b-galpermease Glucose - Lactose + repressor CAP site entry site operator structural genes terminator T transcription stop stop Transcription stop in genes 9.

17. DNA lacZ lacI O lacY lacA C E P CAP pol rep b-gal Glucose - Lactose + repressor CAP site entry site operator structural genes terminator T stop Transcription stop in genes 9.

18. DNA lacZ lacI O lacY lacA C E P CAP pol rep Glucose - Lactose + repressor CAP site entry site operator structural genes terminator T stop Transcription stop in genes 9.

19. DNA lacZ lacI OcOc lacY lacA C E P permeaseb-gal Glucose - Lactose - trans- acetylase The operator is not able to bind the repressor repressor CAP site entry site operator structural genes terminator T CAP pol rep pol The O c mutation of operon 10.

20. DNA lacZ O lacY lacA C E P permeaseb-gal Glucose - Lactose - trans- acetylase The repressor is not able to bind to the operator repressor CAP site entry site operator structural genes terminator T lacI CAP pol rep pol The I - mutation of repressor 11.

21. DNA lacZ O lacY lacA C E P lacI* Glucose - Lactose + The repressor is unable to bind lactose repressor CAP site entry site operator structural genes terminator T CAP pol rep The I s mutation of repressor 12.

22. DNA lacZ lacI O lacY lacA C E P CAP cAMP No glucose CAP is unable to bind cAMP Glucose - Lactose + repressor CAP site entry site operator structural genes terminator T Mutant CAP-I 13.

23. DNA lacZ lacI O lacY lacA C E P cAMP Glükóz - Laktóz + No glucose repressor CAP site entry site operator structural genes terminator T pol CAP Mutant CAP-I 13. CAP is unable to bind cAMP

24. DNA lacZ lacI O lacY lacA C E P CAP can bind promoter in the absence of cAMP Glucose + Lactose + b-gal trans- acetylase rep permease repressor CAP site entry site operator structural genes terminator T CAP pol Mutant CAP-II 14.

25. Too many repressors DNA lacZ lacI O lacA C E P Repressor – on the plasmid repressor CAP site entry site operator structural genes terminator DNA lacI P Glucose - Lactose + DNA T CAP pol rep lacY plasmid DNA lacI P plasmid DNA lacI P plasmid DNA lacI P plasmid rep 15.

26. DNA lacZ lacI O lacA C E P Operator – on the plasmid represssor CAP site entry site operator structural genes terminator DNA Glucose - Lactose - DNA T CAP lacY plasmid O DNA plasmid O DNA plasmid O DNA plasmid O rep b-gal trans- acetylase permease pol Too many operators 16.

27. DNA DNS lacZ lacI OcOc lacY - lacA C E P b-gal Glucose - Lactose - O c mutation – on bacterial DNA perm* T rep CAP pol trans- acetylase 17a. Partial diploids : cis or trans-effect?

28. DNA F plasmid lacZ - lacI O lacY lacA C E P DNA lacZ lacI OcOc lacY - lacA C E P CAP pol b-gal Glucose - Lactose - trans- acetylase O c mutation – on bacterial DNA permease b-gal* trans- acetylase perm* Glucose - Lactose + repressor CAP site entry site operator structural genes terminator T T rep pol rep ColilacO c lacZ + lacY -   -gal: continuously expressed F’lacO + lacZ - lacY +  permease: only with lactose mutation 17b. Partial diploids : cis or trans-effect?

29. DNA lacZ lacI* O lacY - lacA C E P I - mutation – on bacterial DNA DNA F plasmid lacZ - lacI O lacY lacA C E P rep Glucose - Lactose - Glucose - Lactose + b-gal trans- acetylase perm* permease b-gal* repressor CAP site entry site operator structural genes terminator DNA T T CAP pol rep trans- acetylase Coli lacI - lacO + lacZ + lacY -  -gal  with lactose F’ lac I + lacO + lacZ - lacY + permeáz  with lactose mutation 18. Partial diploids : cis or trans-effect?