AINS AND A NEW FAMILY OF AUTOINDUCER SYNTHESIS PROTEINS
AINS AND A NEW FAMILY OF AUTOINDUCER SYNTHESIS PROTEINS
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DOI：
10.1128/jb.177.23.6946-6951.1995
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发表时间：
1995-12-01
影响因子：
3.2
通讯作者：
DUNLAP, PV
中科院分区：
文献类型：
--
作者：
GILSON, L;KUO, A;DUNLAP, PV
在费氏弧菌（Vibrio fischeri）中，自身诱导物N-3-氧代己酰-L-高丝氨酸内酯（AI-1）通过LuxR转录激活因子控制发光操纵子的细胞密度依赖性诱导。最近，我们在大肠杆菌中发现了第二个费氏弧菌自诱导分子，N-辛酰基-L-高丝氨酸内酯（AI-2）。大肠杆菌也通过LuxR激活发光操纵子。这2.7 kb的ain（autoinducer）位点的特点是转座子插入突变，缺失和互补分析，和DNA测序，ii单一的1,185 bp的基因，ainS，被认为是唯一的外源基因所必需的AI-2在大肠杆菌中的合成。此外，费氏弧菌ainS突变体产生AI-1但不产生AI-2，证实在其天然物种中ainS对AI-2的合成是特异性的，预测ainS编码45，580-Da蛋白质，该蛋白质与LuxI或在多种其它细菌中负责合成N-酰基-L-高丝氨酸内酯的任何LuxI同源物都没有相似性，两个不同且不相关的自诱导物合成基因的存在表明在高丝氨酸内酯信号传导分子的合成中发生趋同进化。AinS的C-末端一半显示与哈氏弧菌中推定的蛋白质LuxM同源，LuxM是合成哈氏弧菌生物发光自诱导物所需的。AinS和LuxM定义了一个新的自诱导物合成蛋白家族。此外，另一个基因的预测产物ainR，编码紧接ainS的下游，显示出与LuxN的同源性，LuxN类似地编码在哈维氏弧菌中的luxM的下游，并提出在对哈维氏弧菌自诱导物的生物发光响应中具有传感器/调节器功能。除了与LuxR相互作用外，还在目前未知的条件下与AinR相互作用。
In Vibrio fischeri, the autoinducer N-3-oxohexanoyl-L-homoserine lactone (AI-1) governs the cell density-dependent induction of the luminescence operon via the LuxR transcriptional activator, The synthesis of AI-1 from bacterial metabolic intermediates is dependent on luxI. Recently, we found a second V. fischeri autoinducer molecule, N-octanoyl-L-homoserine lactone (AI-2), that in E. coli also activates the luminescence operon via LuxR, A locus independent of luxI was identified as being required for AI-2 synthesis. This 2.7-kb ain (autoinducer) locus was characterized by transposon insertion mutagenesis, deletion and complementation analysis, and DNA sequencing, ii single 1,185-bp gene, ainS, was found to be the sole exogenous gene necessary for the synthesis of AI-2 in Escherichia coli. In addition, a V. fischeri ainS mutant produced AI-1 but not AI-2, confirming that in its native species ainS is specific for the synthesis of AI-2, ainS is predicted to encode a 45,580-Da protein which exhibits no similarity to LuxI or to any of the LuxI homologs responsible for the synthesis of N-acyl-L-homoserine lactones in a variety of other bacteria, The existence of two different and unrelated autoinducer synthesis genes suggests the occurrence of convergent evolution in the synthesis of homoserine lactone signaling molecules, The C-terminal half of AinS shows homolog to a putative protein in Vibrio harveyi, LuxM, which is required for the synthesis of a V. harveyi bioluminescence autoinducer, Together, AinS and LuxM define a new family of autoinducer synthesis proteins, Furthermore, the predicted product of another gene, ainR, encoded immediately downstream of ainS, shows homology to LuxN, which is similarly encoded downstream of luxM in V. harveyi and proposed to have sensor/regulator functions in the bioluminescence response to the V. harveyi autoinducer, This similarity presents the possibility that AI-2, besides interacting with LuxR, also interacts with AinR under presently unknown conditions.