Role of Quorum Sensing in Sinorhizobium meliloti-Alfalfa Symbiosis
Role of Quorum Sensing in Sinorhizobium meliloti-Alfalfa Symbiosis
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DOI：
10.1128/jb.00376-09
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发表时间：
2009-07-01
影响因子：
3.2
通讯作者：
Gonzalez, Juan E.
中科院分区：
文献类型：
--
作者：
Gurich, Nataliya;Gonzalez, Juan E.
革兰氏阴性土壤细菌紫花苜蓿的ExpR/Sin群体感应系统在与其寄主紫花苜蓿建立共生关系中起着重要作用。不能产生自诱导信号分子(SINI)的突变体缺乏入侵宿主的能力，但矛盾的是，缺乏群体感应转录调控因子ExpR的菌株与野生型一样有效。我们比较了野生型菌株和缺失群体感应调控元件之一的菌株的全基因组表达谱，以确定在细菌生长周期的不同阶段以及在植物中受ExpR/Sin系统控制的基因。我们的分析表明，ExpR是一种高度通用的调节因子，具有独特的能力，可以在存在或不存在自动诱导子的情况下显示不同的调节能力。此外，本研究还为我们深入了解自身诱变突变体所表现出的植物入侵缺陷提供了依据。我们还发现，Expr/Sin群体感应系统在植物入侵后受到抑制。因此，群体感应在许多细胞功能的调节中起着至关重要的作用，这些功能确保了宿主的成功入侵，并在共生关系建立后被灭活。
The ExpR/Sin quorum-sensing system of the gram-negative soil bacterium Sinorhizobium meliloti plays an important role in the establishment of symbiosis with its host plant Medicago sativa. A mutant unable to produce autoinducer signal molecules (sinI) is deficient in its ability to invade the host, but paradoxically, a strain lacking the quorum-sensing transcriptional regulator ExpR is as efficient as the wild type. We compared the whole-genome expression profile of the wild-type strain with strains missing one of the quorum-sensing regulatory components to identify genes controlled by the ExpR/Sin system throughout the different phases of the bacterial growth cycle, as well as in planta. Our analyses revealed that ExpR is a highly versatile regulator with a unique ability to show different regulatory capabilities in the presence or absence of an autoinducer. In addition, this study provided us with insight into the plant invasion defect displayed by the autoinducer mutant. We also discovered that the ExpR/Sin quorum-sensing system is repressed after plant invasion. Therefore, quorum sensing plays a crucial role in the regulation of many cell functions that ensures the successful invasion of the host and is inactivated once symbiosis is established.