Quorum sensing and policing of Pseudomonas aeruginosa social cheaters
Quorum sensing and policing of Pseudomonas aeruginosa social cheaters
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DOI：
10.1073/pnas.1500704112
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发表时间：
2015-02
期刊：
影响因子：
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通讯作者：
Meizhen Wang;A. Schaefer;A. Dandekar;E. Greenberg
中科院分区：
文献类型：
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作者：
Meizhen Wang;A. Schaefer;A. Dandekar;E. Greenberg
重要性合作是受社会欺骗。作弊者从合作者的活动中获益，并获得适应度优势。高等生物防止作弊渗透的一种方法是监管：合作者以一定的代价惩罚作弊者。合作的细菌群体容易受到社会欺骗的影响，但对细菌监管知之甚少。我们已经建立了一个理解的群体感应调节铜绿假单胞菌的合作活动，表明群体感应控制和抗氰化物生产作为一个骗子警务机制。了解细菌如何合作以及它们如何控制社交欺骗具有进化意义，为控制细菌种群的方法提供了重要的见解，并对合成系统设计产生了影响。铜绿假单胞菌是一种机会性人类病原体，当达到足够的人口密度时，它使用群体感应信号级联来激活数十个基因的表达。群体感应控制几个关键毒力因子的产生，包括分泌的蛋白酶如弹性蛋白酶。在蛋白质上生长的细菌的合作群体容易受到群体感应缺陷突变体的社会欺骗。一个可能的限制作弊者出现的方法是通过监管合作者生产昂贵商品的地方来制裁或惩罚作弊者。铜绿假单胞菌LasR-LasI群体感应系统控制基因，包括编码蛋白酶的基因以及编码第二群体感应系统RhlR-RhlI系统的基因，该系统控制许多基因，包括用于氰化物产生的基因。通过使用RhlR群体感应突变体和氰化物合成突变体，我们表明，氰化物的生产是昂贵的和氰化物生产的合作者使用氰化物来惩罚LasR无效的社会骗子。合作者比LasR突变体更不容易受到氰化物的影响。这些实验证明了铜绿假单胞菌中的警务，提供了对警务的机械理解，并表明警务涉及该细菌中两个群体感应系统的级联组织。
Significance Cooperation is subject to social cheating. Cheats benefit from the activity of cooperators and gain a fitness advantage. One way higher organisms prevent infiltration by cheats is policing: Cooperators penalize cheats at some cost to themselves. Cooperating groups of bacteria are susceptible to social cheating, but little is known about bacterial policing. We have built on an understanding a quorum-sensing regulated cooperative activity in Pseudomonas aeruginosa to show that quorum sensing control of and resistance to cyanide production serves as a cheater policing mechanism. Understanding how bacteria cooperate and how they control social cheats has evolutionary implications, provides important insights about ways to control bacterial populations, and has ramifications with respect to synthetic system design. The bacterium Pseudomonas aeruginosa is an opportunistic human pathogen that uses a quorum sensing signal cascade to activate expression of dozens of genes when sufficient population densities have been reached. Quorum sensing controls production of several key virulence factors, including secreted proteases such as elastase. Cooperating groups of bacteria growing on protein are susceptible to social cheating by quorum-sensing defective mutants. A possible way to restrict cheater emergence is by policing where cooperators produce costly goods to sanction or punish cheats. The P. aeruginosa LasR-LasI quorum sensing system controls genes including those encoding proteases and also those encoding a second quorum-sensing system, the RhlR-RhlI system, which controls numerous genes including those for cyanide production. By using RhlR quorum sensing mutants and cyanide synthesis mutants, we show that cyanide production is costly and cyanide-producing cooperators use cyanide to punish LasR-null social cheaters. Cooperators are less susceptible to cyanide than are LasR mutants. These experiments demonstrate policing in P. aeruginosa, provide a mechanistic understanding of policing, and show policing involves the cascade organization of the two quorum sensing systems in this bacterium.