Phylogenetically Novel LuxI/LuxR-Type Quorum Sensing Systems Isolated Using a Metagenomic Approach
Phylogenetically Novel LuxI/LuxR-Type Quorum Sensing Systems Isolated Using a Metagenomic Approach
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DOI：
10.1128/aem.01442-12
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发表时间：
2012-09
影响因子：
4.4
通讯作者：
E. Nasuno;N. Kimura;M. Fujita;C. Nakatsu;Y. Kamagata;S. Hanada
中科院分区：
文献类型：
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作者：
E. Nasuno;N. Kimura;M. Fujita;C. Nakatsu;Y. Kamagata;S. Hanada
为了了解细菌的细胞间信号系统，已经进行了大量的研究，但由于自然环境中的大多数微生物没有培养的代表，我们目前的知识仍然存在很大的差距。宏基因组学是从环境样品中未培养的细菌中鉴定新型群体感应系统的一种方法。本研究分别从森林土壤和焦化厂活性污泥中构建了fosmid宏基因组文库，并利用基于绿色荧光蛋白（GFP）的大肠杆菌生物传感器菌株进行了靶基因的检测。DNA序列分析发现了2对新的luxxi家族n -酰基-l-同源丝氨酸内酯（AHL）合成酶和LuxR家族转录调控因子（克隆N16和N52，分别命名为AubI/AubR和AusI/AusR）。通过核磁共振（NMR）和质谱测定，AubI和AusI各自产生相同的AHL， n -十二烷基-l-高丝氨酸内酯（C12-HSL）。基于氨基酸序列的系统发育分析表明，AusI/AusR来自一个未培养的Betaproteobacteria成员，而AubI/AubR与先前在Proteobacteria分离株中描述的LuxI/LuxR同源物有着非常深的分支。AubI/AubR的系统发育位置表明它们不是最近通过水平基因转移从变形菌门获得的QS系统，而是具有更古老的祖先。通过从未培养的细菌中描述两个新的LuxI/ luxr型QS系统，我们证明了宏基因组筛选有助于进一步了解细菌QS系统的系统发育多样性。
ABSTRACT A great deal of research has been done to understand bacterial cell-to-cell signaling systems, but there is still a large gap in our current knowledge because the majority of microorganisms in natural environments do not have cultivated representatives. Metagenomics is one approach to identify novel quorum sensing (QS) systems from uncultured bacteria in environmental samples. In this study, fosmid metagenomic libraries were constructed from a forest soil and an activated sludge from a coke plant, and the target genes were detected using a green fluorescent protein (GFP)-based Escherichia coli biosensor strain whose fluorescence was screened by spectrophotometry. DNA sequence analysis revealed two pairs of new LuxI family N-acyl-l-homoserine lactone (AHL) synthases and LuxR family transcriptional regulators (clones N16 and N52, designated AubI/AubR and AusI/AusR, respectively). AubI and AusI each produced an identical AHL, N-dodecanoyl-l-homoserine lactone (C12-HSL), as determined by nuclear magnetic resonance (NMR) and mass spectrometry. Phylogenetic analysis based on amino acid sequences suggested that AusI/AusR was from an uncultured member of the Betaproteobacteria and AubI/AubR was very deeply branched from previously described LuxI/LuxR homologues in isolates of the Proteobacteria. The phylogenetic position of AubI/AubR indicates that they represent a QS system not acquired recently from the Proteobacteria by horizontal gene transfer but share a more ancient ancestry. We demonstrated that metagenomic screening is useful to provide further insight into the phylogenetic diversity of bacterial QS systems by describing two new LuxI/LuxR-type QS systems from uncultured bacteria.