chap 12Title chap_12 Created Date 8/20/2002 5:09:18 PM

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

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

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

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

Regulation of Gene Expression12 FIND CHAP TOC

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Table 12.1

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

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

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

Regulation of Gene Expression12 FIND CHAP TOC

galR galE

oE

(–)

(+)cAMP•

CAP

oI

galT galKpG2 pG1

Repressor

Figure 12.7

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

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

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

Regulation of Gene Expression12 FIND CHAP TOC

oE

p1 oI

oI

oE

–60

HU

A

B

+50

GalR

+1

galE

p2

Figure 12.11

Regulation of Gene Expression12 FIND CHAP TOC

tertrpAtrpBtrpCtrpDtrpE

Leaderpolypeptide

trpLptrp

mRNA

trpR

Anthranilatesynthetase

Chorismicacid

anthranilicacid

PRA CDRP InGP tryptophan

Indoleglycerolphosphatesynthetase

Tryptophansynthetase

Figure 12.12

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

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

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

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

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

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

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

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

Regulation of Gene Expression12 FIND CHAP TOC

Box 12.3

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

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