1. a l o c t s e ( I P T G ) l a c I P O l a c Z l a c Y l a c A c r p A R N P o l . A M P C y

2. R e g S t r I R I R

3. Induction Positive Negative
Loss of function DNA binding Effector binding
(total)
Positive
Induction
Repression
Negative
Non inducible
Non de-repressible
Non inducible
Non de-repressible
Non inducible
De-repressed
Constitutive
De-repressed
Constitutive
De-repressed
Non inducible
(super-rep.)
De-repressed

4. +: inducible or repressible c/d: constitutive or derepressed
Positive Negative
R+/R
R+/Rc/d c/d
Rc/d/R- c
R+/R
R+/Rc/d +
Rc/d/R
+: inducible or
repressible
c/d: constitutive or
derepressed
-: non expressed
(non inducible,
non derepressible)

5. lacI+/lacI-(c) lacI+/lacIs(ni) lacIs(ni)/lacI-(c) inducible
Non-inducible
(superepressed)
lacI+/lacIs(ni)
lacIs(ni)/lacI-(c)

6. nirA
NO3-
niiA
niaD
crnA
areA
NH4-

8. nirA+ 1 100 nirA- 1 1 nirA+/nirA+ 1 100 nirA-/nirA- 1 1
niiA
niaD
nirA
nirA
nirA+/nirA
nirA-/nirA
nirA+/nirA
nirA+/nirA
nirA+/nirA S S

9. c
nirA
nirAC
nirA+/nirA
nirAc/nirAc
nirA+/nirAc
nirAc/nirA
nirA+/nirAc c c c

10. Other criteria:
Phenotype of complete loss of function-how to identify them
Frequency of mutations
Phenotype and frequency of revertants of  « - »
chain termination and deletion mutants
in positive
c/d in negative
c/d< or << than -
c/d> or>> than -
reverts rarely to +
-reverts frequentely to c (or d)

11. Two types of mutations: alkalinity mimicking acidity mimicking
pacC
Two types of mutations:
alkalinity mimicking
acidity mimicking
Alkaline pH,
products of pal genes
proteolysis
alkalinity expressed
acidity expressed

12. Induction Positive Negative Loss of function DNA binding Effector
(total) binding
Positive
Induction
Repression
Negative
Non inducible
Non derepressible
De-repressed
Constitutive
(super-rep.)
Constitutive
De-repressed
Non-inducible
(super-rep.)
Non-derepressible
« Real » gain
of function

13. Induction Positive Negative
Loss of function DNA binding Effector binding
(total)
Positive
Induction
Repression
Negative
Non inducible
Non inducible
Non inducible
De-repressed
Constitutive
De-repressed
Constitutive
De-repressed
Non inducible
(super-rep.)
De-repressed

14. active
inactive
1/ / / / /16
(1/4) (1/4)
active ? ? ?
inactive

15. O1 O2 O1 O2

16. M1 M2 + M1 M2

17. l a c I P O1 l a c Z l a c Y l a c A O2 O3
96bp bp

23. a l o c t s e ( I P T G ) l a c I P O l a c Z l a c Y l a c A c r p A R N P o l . A M P C y

24. + O c R S 1 2 + - O c R S 1 2

25. + O c R S 1 2 + - O c R S 1 2

26. const. for S2; inducible for S1 const. for S1; inducible for S2 + - O

27. R S
(IS)
P O S1(Z) S2(Y) S3(A)
R S
(IS)
P OC S1(Z) S2(Y) S3(A)

29. + - O c R S 1 2 + - O c R S 1 2
"

30. S2 S1

31. S2 S1

32. S2 S1 S2 S1 S2 S1 S2 S1

33. GAL10
niaD
GAL1
niiA

34. Elf et al., 2007

35. dilution plating Escherichia coli low IPTG (about 0.1 M) low IPTG+
X-GAL
Escherichia coli
low IPTG
(about 0.1 M)
dilution
plating
Novick and Weiner, 1957

37. Choi et al., Jan 2, 2009

38. Jacob, F., and Monod, J., Genetics regulatory mechanisms in the
synthesis of proteins. J. Mol. Biol. 1961, 3, , reprinted in Taylor,
J. H., Selected papers on Molecular Genetics, 1965, Academic Press
Ptashne, M., A genetic switch: Phage land higher organisms, 1992
Cell press and Blackwell house (there is a 2004 edition).
Muller-Hill, B., The lac operon, 1996, de Gruyter
Ptashne, M.and Gann Alexander, Genes and Signals, Cold Spring
Harbor, 2002