Cell-to-cell communication across the prokaryote-eukaryote boundary
Cell-to-cell communication across the prokaryote-eukaryote boundary
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DOI：
10.1126/science.1077075
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发表时间：
2002-11-08
期刊：
影响因子：
56.9
通讯作者：
Cámara, M
中科院分区：
文献类型：
--
作者：
Joint, I;Tait, K;Cámara, M
细菌能够通过细胞间的通讯进行复杂的组合行为，利用可扩散的化学信号分子，这些分子积累到激活靶基因的阈值浓度(1)。这个过程，被称为“群体感应”，尚未被证明跨越原核-真核生物的界限。在这里，我们展示了细菌生物膜产生的可扩散信号分子被海洋真核生物——绿海藻肠胚藻的浮游阶段利用。Enteromorpha产生可移动的游动孢子，它们探索并暂时停留在表面(2)，但如果表面不理想，就会分离；也就是说，合适的表面似乎被选择用于永久附着。许多因素影响附着，但我们之前已经证明游动孢子附着在生物膜中的细菌细胞上(3)，这表明游动孢子可能感知到细菌产生的化学信号。多种革兰氏阴性菌产生n -酰基高丝氨酸内酯（AHL）群体感应信号分子(4)。一旦达到阈值浓度，AHL通常会激活转录调节蛋白LuxR家族的成员，LuxR/AHL复合体驱动多个靶基因的表达，包括AHL合成所需的基因。当Enteromorpha游动孢子附着在海洋生物膜中的单个细菌细胞上时（图S1），我们研究了Enteromorpha游动孢子是否通过检测ahl来感知细菌的存在。我们采用了三种方法，分别对产生AHL缺陷的鳗弧菌突变体、从重组质粒中表达AHL合成酶的大肠杆菌菌株和人工合成AHL(5)。鳗弧菌是一种革兰氏阴性的海鱼病原体，可形成可繁殖的、吸引虫孢子的生物膜。这种细菌含有两个连接的AHL依赖群体感应电路（VanIR和VanMN），并且已经构建了AHL产生缺陷的突变体(6)。与对照相比，野生型V. anguillarum生物膜强烈增强了游动孢子的沉降（图1A）。然而，在不产生N-己基高丝氨酸内酯（C6-HSL）和N-（3-羟基己基）高丝氨酸内酯（3-OH, C6-HSL）并且也缺乏N-（3-氧癸基）高丝氨酸内酯（30,C10-）的vanM突变体中，没有观察到密度依赖性的附着刺激
Bacteria are capable of complex assemblage behavior through cell-to-cell communication using diffusible chemical signal molecules that accumulate to a threshold concentration that activates target genes (1). This process, termed “quorum sensing,” has not been shown to cross the prokaryote-eukaryote boundary. Here, we show that diffusible signal molecules produced by bacterial biofilms are exploited by the planktonic phase of a marine eukaryotic organism—the green seaweed Enteromorpha.Enteromorpha produces motile zoospores that explore and settle temporarily on a surface (2) but will detach if it is suboptimal; ie, suitable surfaces appear to be selected for permanent attachment. Many factors influence attachment, but we have previously shown that zoospores attach to bacterial cells in biofilms (3), suggesting that zoospores may sense a chemical signal produced by the bacteria. Diverse Gram-negative bacteria produce N-acylhomoserine lactone (AHL) quorum sensing signal molecules (4). Once they reach a threshold concentration, AHLs usually activate members of the LuxR family of transcriptional regulator proteins, and the LuxR/AHL complex drives the expression of multiple target genes, including those required for AHL synthesis. As Enteromorpha zoospores attach to individual bacterial cells in marine biofilms (fig. S1), we investigated whether Enteromorpha zoospores sense the presence of bacteria by detecting AHLs. Three approaches were taken with Vibrio anguillarum mutants defective in AHL production, Escherichia coli strains expressing AHL synthases from recombinant plasmids, and synthetic AHLs (5). V. anguillarum is a Gram-negative marine fish pathogen that forms reproducible, zoospore-attracting biofilms. This bacterium contains two linked AHL-dependent quorum sensing circuits (VanIR and VanMN), and mutants defective in AHL production have been constructed (6). Wild-type V. anguillarum biofilms strongly enhanced zoospore settlement compared with controls (Fig. 1A). However, no density-dependent stimulation of attachment was observed with a vanM mutant that does not produce N-hexanoylhomoserine lactone (C6-HSL) and N-(3-hydroxyhexanoyl) homoserine lactone (3-OH, C6-HSL) and is also deficient for N-(3-oxodecanoyl) homoserine lactone (3O, C10-