Taga Michiko E, Xavier Karina B
Department of Plant and Microbial Biology, University of California, Berkeley, California, USA.
Curr Protoc Microbiol. 2011 Nov;Chapter 1:Unit1C.1. doi: 10.1002/9780471729259.mc01c01s23.
Quorum sensing is a cell-cell signaling process that many bacteria use to regulate gene expression as a function of the density of the population. This phenomenon involves the production, release, and response to small chemical molecules termed autoinducers. Most autoinducers are species-specific; however, one autoinducer called autoinducer-2 (AI-2) is produced and detected by many species of bacteria and thus can foster inter-species communication. This unit describes two assays to detect and quantify AI-2 from biological samples. The first uses a bacterial reporter strain, which produces bioluminescence in response to AI-2. The second is an in vitro assay based on a modified version of an AI-2 receptor fused to a cyan fluorescent protein and a yellow fluorescent protein. Binding of AI-2 to this fusion protein induces a dose-dependent decrease in fluorescence resonance energy transfer (FRET), enabling quantification of the AI-2 concentration in the samples.
群体感应是一种细胞间信号传导过程，许多细菌利用它根据群体密度来调节基因表达。这种现象涉及到被称为自诱导物的小分子化学物质的产生、释放和响应。大多数自诱导物具有物种特异性；然而，一种名为自诱导物-2（AI-2）的自诱导物被许多细菌物种产生和检测到，因此可以促进种间交流。本单元描述了两种从生物样品中检测和定量AI-2的测定方法。第一种方法使用一种细菌报告菌株，该菌株会因AI-2产生生物发光。第二种是基于与青色荧光蛋白和黄色荧光蛋白融合的AI-2受体的改良版本的体外测定方法。AI-2与这种融合蛋白的结合会导致荧光共振能量转移（FRET）呈剂量依赖性降低，从而能够对样品中的AI-2浓度进行定量。
