Glessner A, Smith R S, Iglewski B H, Robinson J B
Department of Biology, University of Dayton, Dayton, Ohio 45469, USA.
J Bacteriol. 1999 Mar;181(5):1623-9. doi: 10.1128/JB.181.5.1623-1629.1999.
Pseudomonas aeruginosa is a ubiquitous environmental bacterium and an important human pathogen. The production of several virulence factors by P. aeruginosa is controlled through two quorum-sensing systems, las and rhl. We have obtained evidence that both the las and rhl quorum-sensing systems are also required for type 4 pilus-dependent twitching motility and infection by the pilus-specific phage D3112cts. Mutants which lack the ability to synthesize PAI-1, PAI-2, or both autoinducers were significantly or greatly impaired in twitching motility and in susceptibility to D3112cts. Twitching motility and phage susceptibility in the autoinducer-deficient mutants were partially restored by exposure to exogenous PAI-1 and PAI-2. Both twitching motility and infection by pilus-specific phage are believed to be dependent on the extension and retraction of polar type 4 pili. Western blot analysis of whole-cell lysates and enzyme-linked immunosorbent assays of intact cells were used to measure the amounts of pilin on the cell surfaces of las and rhl mutants relative to that of the wild type. It appears that PAI-2 plays a crucial role in twitching motility and phage infection by affecting the export and assembly of surface type 4 pili. The ability of P. aeruginosa cells to adhere to human bronchial epithelial cells was also found to be dependent on the rhl quorum-sensing system. Microscopic analysis of twitching motility indicated that mutants which were unable to synthesize PAI-1 were defective in the maintenance of cellular monolayers and migrating packs of cells. Thus, PAI-1 appears to have an essential role in maintaining cell-cell spacing and associations required for effective twitching motility.
铜绿假单胞菌是一种广泛存在于环境中的细菌，也是一种重要的人类病原体。铜绿假单胞菌几种毒力因子的产生是通过两个群体感应系统las和rhl来控制的。我们已经获得证据表明，las和rhl群体感应系统对于4型菌毛依赖性的颤动运动以及菌毛特异性噬菌体D3112cts的感染也是必需的。缺乏合成PAI-1、PAI-2或两种自诱导物能力的突变体在颤动运动和对D3112cts的敏感性方面显著或严重受损。通过暴露于外源性PAI-1和PAI-2，自诱导物缺陷型突变体的颤动运动和噬菌体敏感性得到部分恢复。颤动运动和菌毛特异性噬菌体感染都被认为依赖于极性4型菌毛的伸展和收缩。使用全细胞裂解物的蛋白质印迹分析和完整细胞的酶联免疫吸附测定来测量las和rhl突变体细胞表面菌毛蛋白的量相对于野生型的量。似乎PAI-2通过影响表面4型菌毛的输出和组装在颤动运动和噬菌体感染中起关键作用。还发现铜绿假单胞菌细胞粘附于人支气管上皮细胞的能力依赖于rhl群体感应系统。对颤动运动的显微镜分析表明，无法合成PAI-1的突变体在维持细胞单层和细胞迁移群方面存在缺陷。因此，PAI-1似乎在维持有效颤动运动所需的细胞间间距和关联中起重要作用。
