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

大肠杆菌中的趋化作用是目前研究最多的信号转导模型系统之一。趋化作用中的信号通路相对简单，但以其高敏感性、多刺激整合、宽动态范围和稳健性而闻名。趋化作用中的刺激是由感觉复合体处理的，这些复合体在细胞极点上排列成紧密的簇。信号涉及刺激依赖的组氨酸激酶CHEA的自动磷酸化，以及随后反应调节蛋白Chey的磷酸化。为了补充现有的遗传和生化数据，并更好地了解作为一个整体系统的通路的工作，我们想要在定量水平上分析体内趋化作用的信号处理。我们将使用最近开发的一种基于荧光共振能量转移(FRET)的方法，该方法允许我们量化化学效应器刺激时细胞内蛋白质相互作用的变化。利用FRET，我们可以研究细胞内蛋白质的结合和反应动力学，以及分析不同刺激通过感觉复合体的整合和放大。这些定量数据可直接用于趋化性的计算机模拟。

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.