AinS quorum sensing regulates the Vibrio fischeri acetate switch
AinS quorum sensing regulates the Vibrio fischeri acetate switch
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DOI：
10.1128/jb.00148-08
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发表时间：
2008-09-01
影响因子：
3.2
通讯作者：
Ruby, Edward G.
中科院分区：
文献类型：
--
作者：
Studer, Sarah V.;Mandel, Mark J.;Ruby, Edward G.
海洋细菌费氏弧菌使用两个酰基高丝氨酸内酯（酰基HSL）群体感应系统。较早的信号，辛酰-HSL，产生的AinS，是所需的正常殖民化的鱿鱼Euprymna candiopes，在文化中，是必要的正常生长产量。在检查后者的要求，我们发现，在甘油/胰蛋白胨为基础的培养基中的生长过程中，野生型V. fischeri细胞最初分泌乙酸，但在代谢转变称为乙酸开关，他们随后利用乙酸，将其从培养基中去除。相比之下，在该培养基中生长的ainS突变株不去除排泄的乙酸盐，其累积至致死水平。乙酸转换的特征在于诱导acs（编码乙酰辅酶A（乙酰辅酶A）合成酶的基因），导致排泄的乙酸的摄取。野生型细胞诱导ACS转录报告25倍，与细胞外乙酸酯的消失相一致;相反，ainS突变体没有显示出ACS报告的显着诱导。用辛酰-HSL补充ainS突变体的培养基恢复了正常水平的acs诱导和乙酸盐摄取。额外的突变体分析表明，acs调节是通过调节LitR，但独立的LuxIR群体信号通路。重要的是，V. fischeri的acs突变体在定殖鱿鱼时具有竞争缺陷，表明根据器官共生适当控制乙酸盐代谢的重要性。这是第一个报告的群体感应控制的乙酸开关，它表明乙酸利用和细胞密度之间的代谢联系。
The marine bacterium Vibrio fischeri uses two acyl-homoserine lactone (acyl-HSL) quorum-sensing systems. The earlier signal, octanoyl-HSL, produced by AinS, is required for normal colonization of the squid Euprymna scolopes and, in culture, is necessary for a normal growth yield. In examining the latter requirement, we found that during growth in a glycerol/tryptone-based medium, wild-type V. fischeri cells initially excrete acetate but, in a metabolic shift termed the acetate switch, they subsequently utilize the acetate, removing it from the medium. In contrast, an ainS mutant strain grown in this medium does not remove the excreted acetate, which accumulates to lethal levels. The acetate switch is characterized by the induction of acs, the gene encoding acetyl coenzyme A (acetyl-CoA) synthetase, leading to uptake of the excreted acetate. Wild-type cells induce an acs transcriptional reporter 25-fold, coincident with the disappearance of the extracellular acetate; in contrast, the ainS mutant did not display significant induction of the acs reporter. Supplementation of the medium of an ainS mutant with octanoyl-HSL restored normal levels of acs induction and acetate uptake. Additional mutant analyses indicated that acs regulation was accomplished through the regulator LitR but was independent of the LuxIR quorum-signaling pathway. Importantly, the acs mutant of V. fischeri has a competitive defect when colonizing the squid, indicating the importance of proper control of acetate metabolism in the light of organ symbiosis. This is the first report of quorum-sensing control of the acetate switch, and it indicates a metabolic connection between acetate utilization and cell density.