AUTOINDUCER-MEDIATED REGULATION OF RHAMNOLIPID BIOSURFACTANT SYNTHESIS IN PSEUDOMONAS-AERUGINOSA
AUTOINDUCER-MEDIATED REGULATION OF RHAMNOLIPID BIOSURFACTANT SYNTHESIS IN PSEUDOMONAS-AERUGINOSA
复制标题
DOI：
10.1073/pnas.92.14.6424
复制
发表时间：
1995-07-03
影响因子：
11.1
通讯作者：
REISER, J
中科院分区：
文献类型：
--
作者：
OCHSNER, UA;REISER, J
铜绿假单胞菌是一种重要的致病菌，它能产生多种毒力因子，包括外毒素A、弹性蛋白酶、碱性蛋白酶、藻酸盐、磷脂酶和胞外鼠李糖脂。rhlABR基因簇编码一种调节蛋白（RhlR）和一种鼠李糖基转移酶（RhlAB），这两种蛋白都是合成鼠李糖脂所必需的。另一个基因，rhlI，现已确定下游的rhLABR基因簇。推定的RhlI蛋白与LuxI型细菌自诱导物合成酶具有显著的序列相似性。携带破坏的rhlI基因的铜绿假单胞菌rhlI突变株不能产生鼠李糖脂并且缺乏鼠李糖基转移酶活性。通过将野生型rhlI基因引入到这些菌株中，或者通过添加来自铜绿假单胞菌野生型菌株的无细胞用过的上清液或合成的N-酰基高丝氨酸内酯来恢复鼠李糖脂合成。在rhlI突变株的鼠李糖脂合成的半数最大诱导需要0.5 μ M N-丁酰高丝氨酸内酯或10 μ M N-（3-oxohexanoyl）高丝氨酸内酯。铜绿假单胞菌rhlA启动子在异源宿主恶臭假单胞菌中当rhlR和rhlI基因都存在时或当rhlR基因单独与合成的N-酰基高丝氨酸内酯一起提供时有活性。RhlR-RhlI调节系统被发现是必不可少的弹性蛋白酶的生产，以及和交叉通信之间的RhlR-RhlI鼠李糖脂调节系统和LasR-LasI弹性蛋白酶调节系统被证明。
The opportunistic human pathogen Pseudomonas aeruginosa produces a variety of virulence factors, including exotoxin A, elastase, alkaline protease, alginate, phospholipases, and extracellular rhamnolipids, The previously characterized rhlABR gene cluster encodes a regulatory protein (RhlR) and a rhamnosyltransferase (RhlAB), both of which are required for rhamnolipid synthesis. Another gene, rhlI, has now been identified downstream of the rhLABR gene cluster. The putative RhlI protein shares significant sequence similarity with bacterial autoinducer synthetases of the LuxI type, A P. aeruginosa rhlI mutant strain carrying a disrupted rhlI gene was unable to produce rhamnolipids and lacked rhamnosyltransferase activity. Rhamnolipid synthesis was restored by introducing a wild-type rhlI gene into such strains or, alternatively, by adding either the cell-free spent supernatant from a P. aeruginosa wild-type strain or synthetic N-acylhomoserine lactones. Half-maximal induction of rhamnolipid synthesis in the rhlI mutant strain required 0.5 mu M N-butyrylhomoserine factone or 10 mu M N-(3-oxohexanoyl)homoserine lactone. The P. aeruginosa rhlA promoter was active in the heterologous host Pseudomonas putida when both the rhlR and rhlI genes were present or when the rhlR gene alone was supplied together with synthetic N-acylhomoserine lactones. The RhlR-RhlI regulatory system was found to be essential for the production of elastase as well, and cross-communication between the RhlR-RhlI rhamnolipid regulatory system and the LasR-LasI elastase regulatory system was demonstrated.