Long Tao, Tu Kimberly C, Wang Yufang, Mehta Pankaj, Ong N P, Bassler Bonnie L, Wingreen Ned S
Department of Physics, Princeton University, Princeton, NJ, USA.
PLoS Biol. 2009 Mar 24;7(3):e68. doi: 10.1371/journal.pbio.1000068.
Cell-to-cell communication in bacteria is a process known as quorum sensing that relies on the production, detection, and response to the extracellular accumulation of signaling molecules called autoinducers. Often, bacteria use multiple autoinducers to obtain information about the vicinal cell density. However, how cells integrate and interpret the information contained within multiple autoinducers remains a mystery. Using single-cell fluorescence microscopy, we quantified the signaling responses to and analyzed the integration of multiple autoinducers by the model quorum-sensing bacterium Vibrio harveyi. Our results revealed that signals from two distinct autoinducers, AI-1 and AI-2, are combined strictly additively in a shared phosphorelay pathway, with each autoinducer contributing nearly equally to the total response. We found a coherent response across the population with little cell-to-cell variation, indicating that the entire population of cells can reliably distinguish several distinct conditions of external autoinducer concentration. We speculate that the use of multiple autoinducers allows a growing population of cells to synchronize gene expression during a series of distinct developmental stages.
细菌中的细胞间通讯是一个被称为群体感应的过程，它依赖于对称为自诱导物的信号分子在细胞外积累的产生、检测和响应。通常，细菌使用多种自诱导物来获取有关邻近细胞密度的信息。然而，细胞如何整合和解读多种自诱导物中包含的信息仍然是个谜。我们使用单细胞荧光显微镜，对模式群体感应细菌哈氏弧菌对多种自诱导物的信号响应进行了定量，并分析了其整合情况。我们的结果表明，来自两种不同自诱导物AI-1和AI-2的信号在一条共享的磷酸化信号转导途径中严格以相加的方式组合，每种自诱导物对总响应的贡献几乎相等。我们发现群体中的响应具有一致性，细胞间差异很小，这表明整个细胞群体能够可靠地区分外部自诱导物浓度的几种不同情况。我们推测，使用多种自诱导物可使不断增长的细胞群体在一系列不同的发育阶段同步基因表达。
