Quantitative measurement of signal processing by the chemosensory system of Escherichia coli

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Chemotaxis in Escherichia coli is one of the most-studied model systems for signal transduction. The signalling pathway in chemotaxis is relatively simple but noted for its high sensitivity, integration of multiple stimuli, wide dynamic range, and robustness. Stimuli in chemotaxis are processed by sensory complexes that are organized in tight clusters on the cell poles. Signalling involves stimulus-dependent autophosphorylation of histidine kinase CheA and subsequent phosphorylation of response regulator protein CheY. To complement existing genetic and biochemical data and to better understand the working of a pathway as a whole system, we want to analyze on a quantitative level signal processing in chemotaxis in vivo. We are going to use a recently developed approach based on fluorescence resonance energy transfer (FRET) which allows us to quantify changes in intracellular protein interactions upon stimulation with chemoeffectors. Using FRET we can study protein binding and reaction kinetics in cells, as well as analyze integration and amplification of different stimuli by sensory complexes. These quantitative data can be used directly for computer modelling of chemotaxis.