&
"#
+
•%!&%*
•%)!($*
•
'
"#
LasI
LasR
LasI
Signal diffuses
Cells and signal
accumulate
Signal binds and
activate LasR, a
transcriptional
regulator
Virulence gene
expression
LasR
LasI
Signal synthase
LasR
Signal receptor
LasI
QteE
LasR
LasR
LasI
QteE
LasR
Signal produced
QteE inhibits the
binding of the signal
and LasR
Signal accumulates
Signal binds with
and activates LasR,
the transcriptional
regulator
Virulence gene
expression
LasR
LasI
Signal synthase
LasR
Signal receptor
Microscopy Image
The green fluorescent
protein is controlled
by a QS promoter
The cells will
fluoresce green when
LasR binds the signal
and induces
transcription of QS
genes
GFP
plasmid
Strain 2
Name
Strain 2 Function
Predicted
Results
Initial
Predicted
Results
Final
WT
lasI
Doesn’t produce
LasI signal
synthase, QS can
only respond to
WT-produced
signal
Neither
strain
green
Both turn
green at the
same time
Double mutant,
requires signal
from qteE-,
depends on
diffusion for
signal and QS
qteE- is
green,
lasIqteE- is
not
Both green
Control
Strain 1 Strain 1
Name
Function
(red)
Test
qteEQteE
Produces all
proteins, QS
proceeds as
normal
LasI
Doesn’t
lasIqteEproduce QteE,
can “shortLasI
circuit”
QteE