Inhibition of quorum sensing by a Pseudomonas aeruginosa dksA homologue
Inhibition of quorum sensing by a Pseudomonas aeruginosa dksA homologue
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DOI：
10.1128/jb.183.5.1531-1539.2001
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发表时间：
2001-03-01
影响因子：
3.2
通讯作者：
Van Delden, C
中科院分区：
文献类型：
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作者：
Branny, P;Pearson, JP;Van Delden, C
铜绿假单胞菌las（lasR-lasI）和rhl（rhlR-rhlI）群体感应系统调节几种毒力因子的表达，包括弹性蛋白酶和鼠李糖脂。铜绿假单胞菌菌株PR 1-E4是lasR缺失突变体，其含有第二个未定义的突变，尽管las系统无功能，但该突变允许产生弹性蛋白酶和鼠李糖脂。我们以前已经表明，该菌株通过增加自诱导物合酶基因rhlI的表达来实现这一点。在本报告中，我们表明，突变体PR 1-E4的弹性蛋白溶解表型可以与大肠杆菌dnaK突变抑制基因dksA的铜绿假单胞菌同源物互补。当在多拷贝质粒上以反式提供时，该基因完全抑制突变体PR 1-E4的弹性蛋白酶产生。克隆和北方印迹分析表明，dksA既不突变，也不减少转录突变体PR 1-E4。当过表达时，dksA也减少了突变体PR 1-E4和野生型PAO 1的鼠李糖脂产生。使用北方印迹分析和lacZ报告融合，我们表明，dksA抑制rhlI，rhlAB和lasB转录。外源性N-丁酰-L-高丝氨酸内酯克服了rhlI的表达减少，恢复了rhlAB和lasB的表达，以及弹性蛋白酶的产生。我们的研究结果表明，铜绿假单胞菌DksA同源物的过度生产抑制群体感应依赖性毒力因子的生产下调自诱导合成酶基因rhlI的转录。
The Pseudomonas aeruginosa las (lasR-lasI) and rhl (rhlR-rhlI) quorum-sensing systems regulate the expression of several virulence factors, including elastase and rhamnolipid. P. aeruginosa strain PR1-E4 is a lasR deletion mutant that contains a second, undefined mutation which allows production of elastase and rhamnolipid despite a nonfunctional las system. We have previously shown that this strain accomplishes this by increasing the expression of the autoinducer synthase gene rhlI In this report, we show that the elastolytic phenotype of mutant PR1-E4 can be complemented with a P. aeruginosa homologue of the Escherichia coli dnaK mutation suppressor gene dksA. When supplied in trans on a multicopy plasmid, this gene completely suppressed elastase production by mutant PR1-E4. Cloning and Northern blot analysis revealed that dksA was neither mutated nor less transcribed in mutant PR1-E4. When overexpressed, dksA also reduced rhamnolipid production by both mutant PR1-E4 and the wild type, PAO1. Using Northern blot analysis and lacZ reporter fusions, we show that dksA inhibits rhlI, rhlAB, and lasB transcription. Exogenous N-butyryl-L-homoserine lactone overcame the reduced expression of rhlI and restored rhlAB and lasB expression, as well as elastase production. Our results suggest that the overproduction of the P. aeruginosa DksA homologue inhibits quorum-sensing-dependent virulence factor production by downregulating the transcription of the autoinducer synthase gene rhlI.