Production of acyl-homoserine lactone quorum-sensing signals by gram-negative plant-associated bacteria
Production of acyl-homoserine lactone quorum-sensing signals by gram-negative plant-associated bacteria
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DOI：
10.1094/mpmi.1998.11.11.1119
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发表时间：
1998-11-01
影响因子：
3.5
通讯作者：
Farrand, SK
中科院分区：
文献类型：
--
作者：
Cha, C;Gao, P;Farrand, SK
许多革兰氏阴性细菌根据种群密度调节特定基因组的表达。这种被称为自体诱导或群体感应的调节机制是基于细菌产生一种称为自体诱导剂的小的、可扩散的信号分子。在大多数已研究的体系中，自动诱导剂是L-高丝氨酸内酯的N-酰化衍生物(酰基-HSL)。信号的特异性是由酰基侧链的长度和C-3取代的性质决定的。我们基于根癌农杆菌的tra、鱼腥弧菌的lux、铜绿假单胞菌的LAS和紫罗兰色杆菌的色素生产来评价四种酰基-HSL生物记者对链长从C-4到C-12的3-氧-酰基-HSL、3-羟基酰基-HSL和烷基-HSL的检测能力。来自根癌农杆菌Ti质粒的Trag：：LacZ融合报告是四个检测器中最灵敏和最通用的一个。利用这位记者，我们筛选了106株与植物相关的细菌，分别代表7个属。大多数农杆菌、根瘤菌和泛酸杆菌菌株以及大约一半的欧文氏杆菌和假单胞菌菌株呈阳性反应。只有少数Xanthomonas菌株产生了可检测到的信号。我们用薄层层析法对部分分离株产生的酰基-HSL进行了表征。在假单胞菌和欧文氏杆菌中，大多数产生单一显性活性层析，具有N-(3-氧基己酰基)-L-HSL的性质。然而，少数欧文氏杆菌以及荧光假单胞菌和青枯雷尔氏菌产生了截然不同的信号，包括3-羟基形式，以及活性化合物，其层析性质与我们的任何标准都不同。少数阳性黄单胞菌和几乎所有的农杆菌都能产生少量具有N-(3-氧-辛酰基)-L-HSL层析性质的化合物。根瘤菌属的成员表现出最大的多样性，一些人产生的信号最少，只有一个，另一些人产生的信号多达七个。有几个分离物产生极非极性的化合物，表明有很长的酰基侧链。这些化合物的产生表明，群体感应作为一种基因调控机制在革兰氏阴性植物相关细菌中很常见。
Many gram-negative bacteria regulate expression of specialized gene sets in response to population density. This regulatory mechanism, called autoinduction or quorum-sensing, is based on the production by the bacteria of a small, diffusible signal molecule called the autoinducer. In the most well-studied systems the autoinducers are N-acylated derivatives of L-homoserine lactone (acyl-HSL). Signal specificity is conferred by the length, and the nature of the substitution at C-3, of the acyl side-chain. We evaluated four acyl-HSL bioreporters, based on tra of Agrobacterium tumefaciens, lux of Vibrio fischeri, las of Pseudomonas aeruginosa, and pigment production by Chromobacterium violaceum, for their ability to detect sets of 3-oxo acyl-HSLs, 3-hydroxy acyl-HSLs, and alkanoyl-HSLs with chain lengths ranging from C-4 to C-12. The traG::lacZ fusion reporter from the A. tumefaciens Ti plasmid was the single most sensitive and versatile detector of the four. Using this reporter, we screened 106 isolates representing seven genera of bacteria that associate with plants. Most of the Agrobacterium, Rhizobium, and Pantoea isolates and about half of the Erwinia and Pseudomonas isolates gave positive reactions. Only a few isolates of Xanthomonas produced a detectable signal. We characterized the acyl-HSLs produced by a subset of the isolates by thin-layer chromatography. Among the pseudomonads and erwinias, most produced a single dominant activity chromatographing with the properties of N-(3-oxo-hexanoyl)-L-HSL. However, a few of the erwinias, and the P. fluorescens and Ralstonia solanacearum isolates, produced quite different signals, including 3-hydroxy forms, as well as active compounds that chromatographed with properties unlike any of our standards. The few positive xanthomonads, and almost all of the agrobacteria, produced small amounts of a compound with the chromatographic properties of N-(3-oxo-octanoyl)-L-HSL. Members of the genus Rhizobium showed the greatest diversity, with some producing as few as one and others producing as many as seven detectable signals. Several isolates produced extremely nonpolar compounds indicative of very long acyl side-chains. Production of these compounds suggests that quorum-sensing is common as a gene regulatory mechanism among gram-negative plant-associated bacteria.