chap 12title chap_12 created date 8/20/2002 5:09:18 pm
TRANSCRIPT
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Regulation of Gene Expression12 FIND CHAP TOC
Helix 1
B
A
C
12 13 14 15 16Helix 2
Helix 2
17 18 19 208 9 10 11Turn
1 2 3Helix 1
Helix 1
Amino acids
4 5 6 7
Helix 2:recognition
1
7
12
20
Box 12.1
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Regulation of Gene Expression12 FIND CHAP TOC
Merodiploid Phenotype
1. Lac+
F′
2. Lac–
lac
Interpretation
Complementation;m1 and m2 are in different genes
No complementation;m1 and m2 are in the same gene
m1lac
m2
Figure 12.1
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Regulation of Gene Expression12 FIND CHAP TOC
Merodiploid Phenotype
Lac–
Interpretation
No complementation;the cis-acting lacp mutation prevents expression of lacZ, lacY, and lacAF′ lac
or
I + p+
A+ Y +
Z +
p
O+
O+
Z Y A+
lac
I +
Figure 12.2
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Regulation of Gene Expression12 FIND CHAP TOC
Merodiploid Phenotype
Lac+ inducible lacI is recessive
Interpretation
F′ I
p+
A+ Y +
Z +
p+
O+
O+
Z + Y + A+
lacI
lacI +
Lac constitutive
A
B lacO c is dominantand cis acting
F′ I
p+
A+ Y +
Z +
p+
O+
O c
Z + Y + A+
lacI+
lacI +
ON
Figure 12.3
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Regulation of Gene Expression12 FIND CHAP TOC
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Table 12.1
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Regulation of Gene Expression12 FIND CHAP TOC
Absence oflactose
OFF
ON
RNA Pol
Presence oflactose
lacA
LacI
LacI
Allolactose
lacI lacYlacZlacOlacp
lacAlacI lacYlacZlacOlacp
Figure 12.4
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Regulation of Gene Expression12 FIND CHAP TOC
o3
o3
–82
lacp
o1
o1
+11
+1
o2
+401
A
B
–35
–35TTTAT
–10
–10
Figure 12.5
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Regulation of Gene Expression12 FIND CHAP TOC
ACTCGCGTTGCGTTAATTACACTCAATCGAGTGAGTAATCCG
CAP-binding site
TGGGGTCCGAAATGT GAAATACGAAGGCCGAGC ATACAATTTACA TATGTT
CACACCT+1–10 region–35 regionStop
lacI p o1
TAACACTCGCCTATTGTTAAAGTGTGTCCTTTGTCGATACTGGTAC
Repressor-binding site
fMet Thr
+20+10+1–10–20–30–40–50–60–70–80Promoter Operator
Repressor coding region β-Galactosidasecoding region
Met
RNA polymerase interaction region
mRNA start site
lacZ
Figure 12.6
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Regulation of Gene Expression12 FIND CHAP TOC
galR galE
oE
(–)
(+)cAMP•
CAP
oI
galT galKpG2 pG1
Repressor
Figure 12.7
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Regulation of Gene Expression12 FIND CHAP TOC
Galactose + ATP galactose-1-PO4GalK
Galactose-1-PO4 + UDPglucose UDPgalactose + glucoseGalT
UTP + glucose-1-PO4 UDPglucoseGalU
UDPgalactose UDPglucoseGalE
Figure 12.8
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Regulation of Gene Expression12 FIND CHAP TOC
Repressor
A
RR
gal
R
RRepressor
Multicopyplasmidwith oE
B
R
gal
RR
Repressor
Multicopyplasmidwith oEand oI
C
R
gal
RR
Figure 12.9
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Regulation of Gene Expression12 FIND CHAP TOC
oE o I
RR
RR
R
R
Multiple of 10 bp
Repressors bound to same side of helix
A
Bp2p1
p2p1
p2p1
oE
o I
Multiple of 15 bp
Figure 12.10
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Regulation of Gene Expression12 FIND CHAP TOC
oE
p1 oI
oI
oE
–60
HU
A
B
+50
GalR
+1
galE
p2
Figure 12.11
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Regulation of Gene Expression12 FIND CHAP TOC
tertrpAtrpBtrpCtrpDtrpE
Leaderpolypeptide
trpLptrp
mRNA
trpR
Anthranilatesynthetase
Chorismicacid
anthranilicacid
PRA CDRP InGP tryptophan
Indoleglycerolphosphatesynthetase
Tryptophansynthetase
Figure 12.12
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Regulation of Gene Expression12 FIND CHAP TOC
ABCDtrpE
A In the absence of tryptophan
LO
ptrp
mRNA
trpR
Repressor
ON
ABCDE
B In the presence of tryptophan
LO
ptrp
R
OFF
trp
Figure 12.13
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Regulation of Gene Expression12 FIND CHAP TOC
C
E
D
C
C
C
E
D
C
B
FC
A
E
D
N
N
A
E
D
Helix 1
Helix 2Helix-turn-helix domain:
B
FC
A Aporepressor dimer
B
AporepressorHTH (D + E)
Trp corepressor
RepressorHTH (D + E)
CH2
CH COONH3
Aporepressor - repressor conformational change
Figure 12.14
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Regulation of Gene Expression12 FIND CHAP TOC
araB
L-Ribulosekinase
L-Arabinoseisomerase
L-Ribulose-5- Pepimerase
L-ribuloseL-Arabinose L-ribulose-5- phosphate
D-xylulose-5- phosphate
araIaraO1araO2
CAP site
araC
A
B
pCaraDaraA
pBAD
AraC AraC
AraC
P1 P2
AraC
Arabinose
Arabinose
AraC
Antiactivator Activator
Figure 12.15
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Regulation of Gene Expression12 FIND CHAP TOC
A Absence of arabinose
B Presence of arabinose
Arabinose
P1 form binds to operators of both operons, preventing araBAD expression
P2 form and/or the AraC c (=P2) form binds to I (induction) sites of both operons, activating araBAD transcription
DC c BO I A
D
C +
B
OI
A
P2
P1F′ OFF
OFF
DC c BO I A
D
C +
B
OI
A
P2
P2F′ ON
ON
Figure 12.16
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Regulation of Gene Expression12 FIND CHAP TOC
AraC
araI
pBAD
pC
pC
AraC
araO2
araO1
araC
–300
–100 I1 I2
–200
A Absence of L-arabinose
B Presence of L-arabinose
pBAD
–35 –10
OFF
ON
ON
AraC
araI
I1 I2
AraC
RNA Pol
araBAD mRNA
AraC
pC
araO1
C
OFF
Figure 12.17
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Regulation of Gene Expression12 FIND CHAP TOC
Maltotriose+
Regulation75 min
Amylomaltosephosphorylase
Tactivates
malPmalQ malT
Maltose uptakeMaltose uptake91 min
malFmalG malE IamBmalK malM
I
represses
ON
ON
ON
36 minmalXmalI malY
α-Amylase80 min
malS
Figure 12.18
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Regulation of Gene Expression12 FIND CHAP TOC
Maltose, MaltodextrinsCytoplasmicmembrane
Glucose-6-phosphate
Maltodextrins
LamB
MalS
MalE
MalF MalG
Outer membrane
Periplasmicspace
MalK T MalK
MalQMalP
T TT
Figure 12.19
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Regulation of Gene Expression12 FIND CHAP TOC
CH3
pU
xylC
Upper pathway
MA B N
Toluene
COOH
Benzoate
COOHTCAcycle
Benzoate
pL
xylX
Lower pathway pS
Y Z LT EG F Q K IH xylS xylRpR
XylS
XylR
Figure 12.20
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Regulation of Gene Expression12 FIND CHAP TOC
Box 12.3
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Regulation of Gene Expression12 FIND CHAP TOC
Promoter
4
2
UGAAUG TT
3
1
2:3
Antiterminatorstructure
Readthroughconformation
Terminationconformation3
UUUUUUU
4
3:4
Terminatorhairpin structure
Firststructural
gene
Alternative RNAsecondary structures ofthe leader transcript
1
AGU
AUGRNA
DNATranscription
start
TT 2
1:2
Pausestructure
Pausehairpin
Leader peptidecoding region
Leader peptidecoding region Attenuator
Pause site
ATG TT TGA1 2 3 4
Figure 12.21
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Regulation of Gene Expression12 FIND CHAP TOC
GGUG
CACU
UCC
GCG
G UUGA
CGG
U G
AA
AG C
UUA
CCAC
AUGC
5' ppp–N 26–AUGAAAGCAAU
UU
UC
GUACUGAAAGGUU
1
Ribosomeinitiates
A RNA Pol pauses at 1:2 pause site
B RibosomereleasespausedRNA Pol
2
GCCCGCC
U GA
A A
CGGGCGG
Ribosome
C Attenuation in presence of Trp
3
2
4
140RNA Pol Structural
genes
Regions3 and 4form a terminatorhairpin
RNA Polterminates
Trp
Ser
trpL
GU
UAUUCAC
CA
AU
GACUAACG
UG
G UA
AA
C
CA
CCAUUUUU U
Stop
Trp
fMet
Lys
Arg
ThrArgTrp
TrpGlyLysLeuValPheIleAlaLysMet
D Transcription elongation in absence of Trp
140+1RNA Pol
Structuralgenes
CC
CG
A
AU
A
UU
C
GG
GCA
UAU
GU
G
2
Regions2 and 3base pair,preventing3 and 4 fromforming a terminatorhairpin
4
Lack of trp tRNAcauses ribosome to stall
GlyLysLeuVal
PheIle
AlaLysMet
trpL
GGCUUUUUU
Trp Trp Arg
GCUC
C AA
UA
GC
CG
GA
U AA
UC A
A
3
Figure 12.22