Chemosensing in Escherichia coli: two regimes of two-state receptors.
The chemotaxis network in Escherichia coli is remarkable for its sensitivity to small relative changes in the concentrations of multiple chemical signals. We present a model for signal integration by mixed clusters of interacting two-state chemoreceptors. Our model results compare favorably to the results obtained by Sourjik and Berg with in vivo fluorescence resonance energy transfer. Importantly, we identify two distinct regimes of behavior, depending on the relative energies of the two states of the receptors. In regime I, coupling of receptors leads to high sensitivity, while in regime II, coupling of receptors leads to high cooperativity, i.e., high Hill coefficient. For homogeneous receptors, we predict an observable transition between regime I and regime II with increasing receptor methylation or amidation.
Keymer
Juan E
JE
Department of Molecular Biology, Princeton University, Princeton, NJ 08544-1014, USA.
Endres
Robert G
RG
Skoge
Monica
M
Meir
Yigal
Y
Wingreen
Ned S
NS
D002633:Chemotaxis; D004926:Escherichia coli / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D008024:Ligands; D008954:Models, Biological; D013816:Thermodynamics
D029968:Escherichia coli Proteins; D008024:Ligands