LuxR

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Quorum Sensing
LuxR
LuxR
target gene
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Acyl-Homoserine Lactone Autoinducers
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LuxI-LuxR Quorum Sensing Systems
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Quorum Sensing in V. harveyi
AI-2
LuxQ
H
D
H
D
HTH
LuxU
LuxO
D
H
LuxN
AI-1
LuxCDABE
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Quorum Sensing in E. coli and Salmonella
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Bacteria That Contain luxS
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Page 544
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SAM Utilization
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SAM Utilization
Met
MetK
SAM
SAH
MTA
Pfs
Pfs
SRH
MTR
LuxS?
4,5-Dihydroxy- 2,3-pentanedione HC
?
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SAM Utilization
Met
MetK
SAM
SAH
MTA
Pfs
Pfs
SRH
MTR
LuxS
AI-2 HC
?
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The LuxS Reaction
4,5-Dihydroxy- 2,3-pentanedione
SRH
Homocysteine

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AI-2 Could be a Furanone
MHF
DMHF
HF
DHCP
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Quorum Sensing in V. harveyi
AI-2
LuxQ
H
D
H
D
HTH
LuxU
LuxO
D
H
LuxN
AI-1
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Holo-LuxP
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Boron is ubiquitous in the biosphere
Sea water 0.4 mM (primarily boric acid) L.A. tap
water 40 µM Soils 2-100 ppm Marine plants 120
ppm Land plants 50 ppm Marine animals 20-50
ppm Land animals 0.5 ppm
Boron is required by a number of organisms,
but for poorly characterized reasons
Vascular plants cell wall? pollination? Diatoms Cy
anobacteria heterocyst formation Zebrafish embry
ogenesis
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11B NMR
holo-LuxP
filtered
apo-LuxP
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Synthesis of AI-2
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Boric Acid Induces Lux in V. harveyi
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Synthesis of AI-2
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Targets of AI-2
Vibrio harveyi Bioluminescence, Biofilms Vibrio
cholerae Virulence, Biofilms Salmonella
typhimurium ABC
transporter Salmonella typhi Biofilms Escherichi
a coli O157H7 Type III Secretion
(virulence) Porphyromonas gingivalis Hemin
acquisition genes, virulence factors Shigella
flexneri VirB (virulence factor) Streptococcu
s pyogenes Secreted
protease Actinobacillus actinomycetemcomitans
Periodontal virulence, Mixed-species
biofilms Photorhabdus luminescens Antibiotic
production Neisseria meningitidis
Virulence/bacteremia Borrelia burgdorferi
Virulence Clostridium
perfringens Virulence Campylobacter
jejuni Motility Microarrays Escherichi
a coli K12 300 genes Escherichia
coli O157H7 400 genes Vibrio cholerae El
Tor 70 genes (virulence regulon)
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Biosynthesis of AI-1 and AI-2
Met
MetK
LuxI
SAM
LuxLM
AI-1
SAH
MTA
Pfs
Pfs
SRH
MTR
LuxS
AI-2 HC
?
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Quorum Sensing in V. harveyi
AI-2
LuxQ
H
D
H
D
HTH
LuxU
LuxO
D
H
LuxN
AI-1