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

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Chemotaxis allows bacteria to sense their environment and find conditions that are optimal for growth and cell function, including formation of bacterial communities and virulence. Chemotaxis of Escherichia coli has developed over the years into one of the most thoroughly studied model systems for signal transduction and simple behaviour, and for understanding the evolutionary network optimization. It yielded many general insights into such properties of cellular networks as signal amplification and robustness. However, despite large variety of known environmental stimuli that can be sensed by the chemotaxis pathway of E. coli, detailed studies of chemotactic signalling have been largely limited to few chemical ligands. The goals of this project are therefore to better understand the sensory spectrum of the chemotaxis pathway in its relation to cell physiology. We will systematically quantify chemotactic responses to key metabolites and known substrates of E. coli transporter systems, and analyze the relation between chemotaxis, uptake and metabolism. Furthermore, we will investigate modes of signalling by a number of environmental stimuli, including pH, aromatic compounds, alcohols, osmolarity, salts, and quorum-sensing signals, and study the integration of these stimuli by the pathway.