7/23/2019 Ch 07 Lecture 12
1/49
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
7/23/2019 Ch 07 Lecture 12
2/49
2015 Pearson Education, Inc.
7.8 Regulation of Chemotais
&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 $rotein
Che results in countercloc"ise rotation and runs
Che#P results in cloc"ise rotation and tum/ling
7/23/2019 Ch 07 Lecture 12
3/49
2015 Pearson Education, Inc.
7.8 Regulation of Chemotais
&te$ -da$tation Feedback loop
-llo"s the s%stem to reset itself to continue to sense the
$resence of a signal
In3ol3es modification of !CPs
7/23/2019 Ch 07 Lecture 12
4/49
2015 Pearson Education, Inc. Figure 7.19
Repellents bind to MCP and
trigger phosphorylation of
CheA-CheW cople!.
CheA-CheW
phosphorylate
Che" and Che#.MCP is both
ethylated
and
deethylated.
Che$ 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$
7/23/2019 Ch 07 Lecture 12
5/49
2015 Pearson Education, Inc.
7.8 Regulation of Chemotais
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 $rotein monitors o%gen le3el
7/23/2019 Ch 07 Lecture 12
6/49
2015 Pearson Education, Inc.
7.* 6uorum &ensing
Proar%otes can res$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
$athogenic /acterium+
7/23/2019 Ch 07 Lecture 12
7/49 2015 Pearson Education, Inc.
7.* 6uorum &ensing
Each s$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
7/23/2019 Ch 07 Lecture 12
8/49 2015 Pearson Education, Inc.
Acyl hooserine lactone 'A()*
A()Acti+ator protein
A()
Chroosoe A() synthase
,ther cells
of the sae
species
Quorum-
specific
proteins
Figure 7.
7/23/2019 Ch 07 Lecture 12
9/49
2015 Pearson Education, Inc.
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 $roduction in /acteria includingAliivibrio ischeri ()igure 7.21+ !ux operonencodes /ioluminescence
7/23/2019 Ch 07 Lecture 12
10/49
2015 Pearson Education, Inc. Figure 7.1
7/23/2019 Ch 07 Lecture 12
11/49
2015 Pearson Education, Inc.
7.* 6uorum &ensing
Eam$les of uorum sensing :irulence factors
&"itching from free#li3ing to gro"ing as a /iofilm
6uorum sensing is $resent in some micro/ial
euar%otes 6uorum sensing liel% eists inArchaea
7/23/2019 Ch 07 Lecture 12
12/49
2015 Pearson Education, Inc.
7.* 6uorum &ensing
:irulence factors "scherichia coli 45797
&higa toin;$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+
7/23/2019 Ch 07 Lecture 12
13/49
2015 Pearson Education, Inc.
/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
7/23/2019 Ch 07 Lecture 12
14/49
2015 Pearson Education, Inc.
7.* 6uorum &ensing
:irulence factors (cont
7/23/2019 Ch 07 Lecture 12
15/49
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
7/23/2019 Ch 07 Lecture 12
16/49
2015 Pearson Education, Inc.
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 $roduction and flagella
s%nthesis ()igure 7.2+
7/23/2019 Ch 07 Lecture 12
17/49
2015 Pearson Education, Inc.
Production
of A()s and
c-di-MP
4!opolysaccharide
production and
flagella synthesis
/ncreasingcell
population AttachentMature
biofil
Figure 7.0
7/23/2019 Ch 07 Lecture 12
18/49
2015 Pearson Education, Inc.
7.10 4ther >lo/al Control ?et"ors
&e3eral other glo/al control s%stems -ero/ic and anaero/ic res$iration
Cata/olite re$ression
?itrogen utili@ation
4idati3e stress &4& res$onse
$eat shock response
7/23/2019 Ch 07 Lecture 12
19/49
2015 Pearson Education, Inc.
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
$eat shock responsealso occurs inArchaea
7/23/2019 Ch 07 Lecture 12
20/49
2015 Pearson Education, Inc.
Rpo(
&na :oral
protein
&enatured
protein
&egradation of
Rpo( by protease
Rpo(
Proteins unfold at
high teperature.
Rpo( is
released.
&na binds
and refolds
proteins.
Rpo( is free
to transcribe
heat shoc2
genes.
Hightemperature
Low
tem
perature
Figure 7.;
7/23/2019 Ch 07 Lecture 12
21/49
2015 Pearson Education, Inc.
I:. Regulation of e3elo$ment in !odel
%acteria 7.11 &$orulation in %acillus
7.12 Caulo/acter ifferentiation
7.1 ?itrogen )iation, ?itrogenase, and
9eteroc%st )ormation
7/23/2019 Ch 07 Lecture 12
22/49
2015 Pearson Education, Inc.
7.11 &$orulation in %acillus
Regulation of de3elo$ment in model /acteria &ome $roar%otes dis$la% the /asic $rinci$le of
differentiation
Endos$ore formation in %acillus()igure 7.25+
Controlled /% four sigma factors )orms inside mother cell
'riggered /% ad3erse eternal conditions (i.e., star3ation
or desiccation+
7/23/2019 Ch 07 Lecture 12
23/49
2015 Pearson Education, Inc.
External signals for sporulation
desiccationcell densitystar+ation
poA
po//4
po//A#
7/23/2019 Ch 07 Lecture 12
24/49
2015 Pearson Education, Inc.
7.12 Caulobacterifferentiation
Caulobacter$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
7/23/2019 Ch 07 Lecture 12
25/49
2015 Pearson Education, Inc. Figure 7.?
7/23/2019 Ch 07 Lecture 12
26/49
2015 Pearson Education, Inc.
7.1 ?itrogen )iation, ?itrogenase, and
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
7/23/2019 Ch 07 Lecture 12
27/49
2015 Pearson Education, Inc.
7.1 ?itrogen )iation, ?itrogenase, and
9eteroc%st )ormation 9ighl% regulated $rocess /ecause it is such an
energ%#demanding $rocess
'i reguloncoordinates regulation of genes
essential to nitrogen fiation ()igure 7.27+
4%gen and ammonia are the t"o main regulator%effectors
7/23/2019 Ch 07 Lecture 12
28/49
2015 Pearson Education, Inc.
FeMo-co
synthesis
Regulators
FeMo-cosynthesis
Mo
process-
ing
(oocitratesynthesis
Metal center
biosynthesis
FeMo-co
insertion into
dinitrogenase
:egati+ePositi+e
&initro-
genasereductase
processing
Fla+odo!in
FeMo-co
synthesis
:itrogenase
proteins
&initrogenase
reductase
&initro-
genase
4lectrontransport
Pyru+ate
fla+odo!in
o!ido-
reductase
!A
"!A
Q B A L F M Z W V S U X N E Y T K D H J
nif
@
Figure 7.7
7/23/2019 Ch 07 Lecture 12
29/49
2015 Pearson Education, Inc.
7.1 ?itrogen )iation, ?itrogenase, and
9eteroc%st )ormation 9eteroc%st formation ()igure 7.28+
Reuires meta/olic and mor$hological changes
)ormation of thicened en3elo$e
Inacti3ation of $hotos%stem II
E$ression of nitrogenase
Patterning of heteroc%st differentiation
7/23/2019 Ch 07 Lecture 12
30/49
2015 Pearson Education, Inc.
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
7/23/2019 Ch 07 Lecture 12
31/49
2015 Pearson Education, Inc.
:. 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
7/23/2019 Ch 07 Lecture 12
32/49
2015 Pearson Education, Inc.
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?-
7/23/2019 Ch 07 Lecture 12
33/49
2015 Pearson Education, Inc.
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
7/23/2019 Ch 07 Lecture 12
34/49
2015 Pearson Education, Inc.
7.1A Regulator% R?- &mall R?-s and
-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
7/23/2019 Ch 07 Lecture 12
35/49
2015 Pearson Education, Inc.
7.1A Regulator% R?- &mall R?-s and
-ntisense R?- '%$es of small R?-s (cont
7/23/2019 Ch 07 Lecture 12
36/49
2015 Pearson Education, Inc.
all regulatory
R:A
all regulatory
R:A recognition se6uence
(f6
protein
)E*E
m"!A
Figure 7.0
7 15 Ri/ it h
7/23/2019 Ch 07 Lecture 12
37/49
2015 Pearson Education, Inc.
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 $lants
7/23/2019 Ch 07 Lecture 12
38/49
2015 Pearson Education, Inc. Figure 7.01
7 1 -tt ti
7/23/2019 Ch 07 Lecture 12
39/49
2015 Pearson Education, Inc.
7.1 -ttenuation
'ranscri$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
7/23/2019 Ch 07 Lecture 12
40/49
2015 Pearson Education, Inc.
!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
7/23/2019 Ch 07 Lecture 12
41/49
2015 Pearson Education, Inc.
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
7/23/2019 Ch 07 Lecture 12
42/49
2015 Pearson Education, Inc.
: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
7/23/2019 Ch 07 Lecture 12
43/49
2015 Pearson Education, Inc.
7.17 )eed/ac Inhi/ition
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
7/23/2019 Ch 07 Lecture 12
44/49
2015 Pearson Education, Inc.
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
7/23/2019 Ch 07 Lecture 12
45/49
2015 Pearson Education, Inc.
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
7/23/2019 Ch 07 Lecture 12
46/49
2015 Pearson Education, Inc.
7.17 )eed/ac Inhi/ition
&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
7/23/2019 Ch 07 Lecture 12
47/49
2015 Pearson Education, Inc.
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
7/23/2019 Ch 07 Lecture 12
48/49
2015 Pearson Education, Inc.
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+
7/23/2019 Ch 07 Lecture 12
49/49
lutaine
concentration
9S 9S-A:P; 9S-A:P'+
AMP.ully acti%e Half acti%e 3nacti%e
4nye
acti+ity
lutaine
Recommended