Ch 07 Lecture 12

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2015 Pearson Education, Inc.

7.8 Regulation of Chemotais

!odified t"o#com$onent s%stem used in

chemotaxisto &ense tem$oral changes in attractants or re$ellents

Regulate flagellar rotation

'hree main ste$s ()igure 7.1*+1. Res$onse to signal

2. Controlling flagellar rotation

. -da$tation

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&te$ 1 Res$onse to signal &ensor% $roteins in c%to$lasmic mem/rane sense

attractants and re$ellents

Methyl-accepting chemotaxis proteins (MCPs)

ind attractant or re$ellent and initiate flagellar rotation

&te$ 2 Controlling flagellar rotation Controlled /% Che $rotein

Che results in countercloc"ise rotation and runs

Che#P results in cloc"ise rotation and tum/ling

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&te$ -da$tation Feedback loop

-llo"s the s%stem to reset itself to continue to sense the

$resence of a signal

In3ol3es modification of !CPs

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2015 Pearson Education, Inc. Figure 7.19

Repellents bind to MCP and

trigger phosphorylation of

CheA-CheW cople!.

CheA-CheW

phosphorylate

Che" and Che#.MCP is both

ethylated

and

deethylated.

Che$ dephosphorylates

Che"-P.

Che"-P binds to

flagellar s%itch.

CheR

Che#

Che#

P Che" Che"

CheWCheA

P

A&P

P

Flagellar

otor

Flagellu

Cytoplas

MCP

Che$

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4ther 'aes Che $roteins also $la% a role in these

Phototaxis mo3ement to"ard light

ight sensor re$laces !CPs

Aerotaxis mo3ement to"ard o%gen

Redo $rotein monitors o%gen le3el

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7.* 6uorum &ensing

Proar%otes can res$ond to the $resence of other

cells of the same s$ecies

Quorum sensing mechanism /% "hich /acteria

assess their $o$ulation densit%

Ensures that a sufficient num/er of cells are $resent/efore initiating a res$onse that, to /e effecti3e, reuires

a certain cell densit% (e.g., toin $roduction in

$athogenic /acterium+

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7.* 6uorum &ensing

Each s$ecies of /acterium $roduces a s$ecific

autoinducermolecule ()igure 7.20+ iffuses freel% across the cell en3elo$e

Reaches high concentrations inside cell onl% if man%

cells are near

inds to s$ecific acti3ator $rotein and triggers

transcri$tion of s$ecific genes

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Acyl hooserine lactone 'A()*

A()Acti+ator protein

A()

Chroosoe A() synthase

,ther cells

of the sae

species

Quorum-

specific

proteins

Figure 7.

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7.* 6uorum &ensing

&e3eral different classes of autoinducers Acyl homoserine lactone(-9+ "as the first autoinducer

to /e identified

6uorum sensing first disco3ered as mechanism

regulating light $roduction in /acteria includingAliivibrio ischeri ()igure 7.21+ !ux operonencodes /ioluminescence

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7.* 6uorum &ensing

Eam$les of uorum sensing :irulence factors

&"itching from free#li3ing to gro"ing as a /iofilm

6uorum sensing is $resent in some micro/ial

euar%otes 6uorum sensing liel% eists inArchaea

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7.* 6uorum &ensing

:irulence factors "scherichia coli 45797

&higa toin;$roducing strain

Produces -9 -I#

E$ine$hrine $lus nore$ine$hrine $lus -I# /ind to sensor

molecules in $lasma mem/rane

-cti3ates motilit%, enterotoin $roduction, and

$roduction of 3irulence $roteins ()igure 7.22a+

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/ntestinal cell

/ntestinal

horonesA/-0

ensor 2inases

3ranscriptional

regulators

A/-0

synthase 4nteroto!in

E. coli cell

Virulence factor production in Shiga toxin-

producing Escherichia coli

Acti+ate

Acti+ate

3o!in

production

Acti+ate

Figure 7.a

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7.* 6uorum &ensing

:irulence factors (cont

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2015 Pearson Education, Inc. Figure 7.b

Virulence factor production in Staphylococcus

A/P

A&P

ATP

Cytoplasic

ebrane

Cytoplas

#asal transcription 5irulence proteins

ArgA P

P

ArgCArg#

Pre-A/P

Pre-A/P iscon+erted to

A/P by Arg#

and e!ported

out of the cell.

ArgC phosphorylates

ArgA.

ArgA-P acti+ates

e!pression of genes

re6uired for pre-A/P

and +irulence proteins.

#inding of A/P to

ArgC leads to

auto-phosphorylation.

D C B argA enes encoding +irulence

8 8

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7.* 6uorum &ensing

iofilm formation Pseudomonas aeruginosa

Produces $ol%saccharides that increase $athogenicit%

and anti/iotic resistance

'"o uorum#sensing s%stems

Produces -9s and c%clic di#guanosine mono$hos$hate(c#di#>!P+

eads to eo$ol%saccharide $roduction and flagella

s%nthesis ()igure 7.2+

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Production

of A()s and

c-di-MP

4!opolysaccharide

production and

flagella synthesis

/ncreasingcell

population AttachentMature

biofil

Figure 7.0

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7.10 4ther >lo/al Control ?et"ors

&e3eral other glo/al control s%stems -ero/ic and anaero/ic res$iration

Cata/olite re$ression

?itrogen utili@ation

4idati3e stress &4& res$onse

$eat shock response

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7.10 4ther >lo/al Control ?et"ors

$eat shock response argel% controlled /% alternati3e sigma factors

()igure 7.2A+

$eat shock proteins counteract damage of denatured

$roteins and hel$ cell reco3er from tem$erature stress

:er% ancient $roteins

$eat shock responsealso occurs inArchaea

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Rpo(

&na :oral

protein

&enatured

protein

&egradation of

Rpo( by protease

Rpo(

Proteins unfold at

high teperature.

Rpo( is

released.

&na binds

and refolds

proteins.

Rpo( is free

to transcribe

heat shoc2

genes.

Hightemperature

Low

tem

perature

Figure 7.;

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I:. Regulation of e3elo$ment in !odel

%acteria 7.11 &$orulation in %acillus

7.12 Caulo/acter ifferentiation

7.1 ?itrogen )iation, ?itrogenase, and

9eteroc%st )ormation

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7.11 &$orulation in %acillus

Regulation of de3elo$ment in model /acteria &ome $roar%otes dis$la% the /asic $rinci$le of

differentiation

Endos$ore formation in %acillus()igure 7.25+

Controlled /% four sigma factors )orms inside mother cell

'riggered /% ad3erse eternal conditions (i.e., star3ation

or desiccation+

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External signals for sporulation

desiccationcell densitystar+ation

poA

po//4

po//A#

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7.12 Caulobacterifferentiation

Caulobacter$ro3ides another eam$le of differentiation

'"o forms of cells #&armer cells dis$ersal role

#talked cells re$roducti3e role

Controlled /% three maBor regulator% $roteins ()igure 7.2+

Eternal stimuli and internal factors $la% a role in affecting life c%cle

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2015 Pearson Education, Inc. Figure 7.?

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9eteroc%st )ormation ?itrogen fiation is $rocess of reducing ?2to ?9

4nl% certain $roar%otes can fi nitrogen

Reaction is catal%@ed /% nitrogenase Com$osed of dinitrogenase and dinitrogenase

reductase &ensiti3e to the $resence of o%gen

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9eteroc%st )ormation 9ighl% regulated $rocess /ecause it is such an

energ%#demanding $rocess

'i reguloncoordinates regulation of genes

essential to nitrogen fiation ()igure 7.27+

4%gen and ammonia are the t"o main regulator%effectors

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FeMo-co

synthesis

Regulators

FeMo-cosynthesis

Mo

process-

ing

(oocitratesynthesis

Metal center

biosynthesis

FeMo-co

insertion into

dinitrogenase

:egati+ePositi+e

&initro-

genasereductase

processing

Fla+odo!in

FeMo-co

synthesis

:itrogenase

proteins

&initrogenase

reductase

&initro-

genase

4lectrontransport

Pyru+ate

fla+odo!in

o!ido-

reductase

!A

"!A

Q B A L F M Z W V S U X N E Y T K D H J

nif

@

Figure 7.7

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9eteroc%st )ormation 9eteroc%st formation ()igure 7.28+

Reuires meta/olic and mor$hological changes

)ormation of thicened en3elo$e

Inacti3ation of $hotos%stem II

E$ression of nitrogenase

Patterning of heteroc%st differentiation

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A filament of Ana#aena Heterocyst$%egetati%e cell interactions Triggering heterocyst formation

5egetati+e cells5egetati+e cells

(eterocyst

B@-etoglutarate

:tcA acti+ates

h!"e!pression

(etR acti+ates genes necessary

for heterocyst foration

Fi!ed : flo%

Fi!ed C flo%

Figure 7.D

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:. R?-#ased Regulation

7.1A Regulator% R?-s &mall R?-s and

-ntisense R?-

7.15 Ri/os"itches

7.1 -ttenuation

1A R l R?- & ll R?- d

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7.1A Regulator% R?- &mall R?-s and

-ntisense R?- egulatory 'A moleculeseert their effects /%

/ase $airing "ith mR?- ()igure 7.2*+ loc a ri/osome#/inding site (R&+

4$en u$ a /loced R&

Increase degradation of mR?-

ecrease degradation of mR?-

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Translation inhi#ition&stimulation"!A degradation&protection

'( '(

)E *E )E *E

)E*Em"!A

R#

R#

3ranslation

3ranslation

:o translation

:o translation

R#

s"!A

R#)E

)E

*E

)E*E *E

R# R#

m"!As"!A

:o translation3ranslation

:o translation 3ranslation

R# R#*E)E )E

)E*E+( +(

Ribonuclease

Ribonuclease

*E

)E *E *E)E*E

)E

Figure 7.9

7 1A R l t R?- & ll R?- d

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-ntisense R?- '%$es of small R?-s

&mall R?-s made /% transcri/ing nontem$late strand of

gene are called antisense 'As

Each antisense R?- can regulate multi$le mR?-s

'ranscri$tion of antisense R?- is enhanced "hen its

target genes need to /e turned off &ome antisense R?-s actuall% enhance translation

7 1A R l t R?- & ll R?- d

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-ntisense R?- '%$es of small R?-s (cont

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all regulatory

R:A

all regulatory

R:A recognition se6uence

(f6

protein

)E*E

m"!A

Figure 7.0

7 15 Ri/ it h

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7.15 Ri/os"itches

ibos&itches R?- domains in an mR?- molecule

that can /ind small molecules to control translationof mR?- ()igure 7.1+ ocated at 5D end of mR?-

inding results from folding of R?- into a # structure

&imilar to a $rotein recogni@ing a su/strate

Ri/os"itch control is analogous to negati3e control

)ound in some /acteria, fungi, and $lants

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7 1 -tt ti

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7.1 -ttenuation

'ranscri$tional control that functions /%

premature termination o m'A synthesis Control eerted after the initiation of transcri$tion, /ut /efore its

com$letion

)irst eam$le "as the tr%$to$han o$eron in "* coli()igure 7.2+

m'A stem+loopstructure and s%nthesis of leader peptideare

determining factors in attenuation ()igure 7.+

>enomic e3idence suggests attenuation eists inArchaea

!r# structural genes$ % L

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!r#structural genes

!r#D!r#E !r#C !r#B !r#A

Trp Leader

!A

$ % L

Met-)ys-Ala-lle-Phe-5al-)eu-)ys-ly-3rp-3rp-Arg-3hr-er

Threonine

Histidine

Phenylalanine

Met-)ys-Arg-/le-er-3hr-3hr-/le-3hr-3hr-3hr-/le-3hr-

/le-3hr-3hr-ly-Asn-ly-Ala-ly

Met-3hr-Arg-5al-ln-Phe-)ys-(is-(is-(is-(is-(is-(is-(is-Pro-Asp

Met-)ys-(is-/le-Pro-Phe-Phe-Phe-Ala-Phe-Phe-

Phe-3hr-Phe-Pro

Figure 7.0

Excess tryptophan, )eader se6uence

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Excess tryptophan,

transcription

terminated !A

m"!A

!A

Limiting tryptophan,

transcription

proceeds

)eader se6uence

&irection of

transcription

Ribosoe

#ase

pairing

3rp-rich

leader

peptide &irection of

translation

R:A

polyerase

terinates

)E

)E

&irection of

translation

R:A

polyerase

continues

&irection of

transcription3ranslation

stalled

)eader

peptide

'

+ *

!r

#E

!r#

E

'

+

*

)eader se6uence

3ranscription

terinated and

tryptophan

structural

genes not

transcribed

3ranscription

continues and

tryptophan

structural genes

transcribed

Figure 7.00

:I Regulation of En@%mes and 4ther Proteins

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:I. Regulation of En@%mes and 4ther Proteins

7.17 )eed/ac Inhi/ition

7.18 Post#'ranslational Regulation

7 17 )eed/ac Inhi/ition

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Feedback inhibition mechanism for turning off the

reactions in a /ios%nthetic $ath"a% ()igure 7.Aa+ End $roduct of the $ath"a% /inds to the first en@%me in

the $ath"a%, thus inhi/iting its acti3it%

Inhi/ited en@%me is an allostericen@%me ()igure 7.A/+

'"o /inding sites acti3e and allosteric

Re3ersi/le reaction

3he

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3he

allosteric

enyeStarting su#strate

.eed#ac/ inhi#ition

En0yme 1

En0yme 2

En0yme

End product

/nterediate /

/nterediate //

/nterediate ///

Feedbac2

inhibition

of first

enye

shuts

do%n

path%ay.

En0yme A

Figure 7.0;a

4nd product

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Allosteric site

Acti%e site

Allosteric inhi#ition

3!H313T34!,

ubstrate

cannot bind=no reaction.

A2T3V3T5,

4nyereaction

proceeds.

4nd product

'allosteric

effector*

ubstrate

4nye

Figure 7.0;b

7 17 )eed/ac Inhi/ition

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&ome $ath"a%s controlled /% feed/ac inhi/ition

use isoen@%mes ,soenymes

ifferent en@%mes that catal%@e the same reaction /ut

are su/Bect to different regulator% controls ()igure 7.Ac+

Phosphoenol 4rythrose 3nitial

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Phosphoenol-

pyru+ate

4rythrose

;-phosphate8

3nitial

su#strates

AHP

synthases

6isoen0ymes'7 +7 *8

Acti+ity ofpath%ay is

partiallyreducedby e!cessof anyone endproduct.

.inal

products

1 0

&A(P

Chorisate

3yrosine

Phenylalanine

3ryptophan

3soen0yme inhi#ition Figure 7.0;c

7 18 Post 'ranslational !odification

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7.18 Post#'ranslational !odification

ios%nthetic en@%mes can also /e regulated /%

co3alent modifications Regulation in3ol3es a small molecule attached to or

remo3ed from the $rotein ()igure 7.5+

Results in conformational change that inhi/its acti3it%

Common modifiers include adenosine mono$hos$hate

(-!P+, adenosine di$hos$hate (-P+, inorganic

$hos$hate (P4A2#+, and meth%l grou$s (C9+

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lutaine

concentration

9S 9S-A:P; 9S-A:P'+

AMP.ully acti%e Half acti%e 3nacti%e

4nye

acti+ity

lutaine

Documents

Ch 07 Lecture 12