Stress-Induced Outer Membrane Vesicle Production by Pseudomonas aeruginosa
Stress-Induced Outer Membrane Vesicle Production by Pseudomonas aeruginosa
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DOI：
10.1128/jb.02267-12
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发表时间：
2013-07-01
影响因子：
3.2
通讯作者：
Kuehn, Meta J.
中科院分区：
文献类型：
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作者：
MacDonald, Ian A.;Kuehn, Meta J.
铜绿假单胞菌作为一种机会性革兰氏阴性病原菌，在感染过程中必须能够适应和生存环境的变化和压力。为了帮助在敌对的宿主环境中生存，铜绿假单胞菌已经进化出防御机制，包括产生胞外多糖胶囊和分泌无数降解蛋白酶和脂肪酶。外膜衍生囊泡（OMV）的产生是毒力因子的分泌机制，也是细菌对毒力作用应激因子的一般反应。本研究调查了亚致死生理应激对铜绿假单胞菌OMV生产的影响，以及假单胞菌喹诺酮信号（PQS）和MucD周质蛋白酶是否是这种反应的关键机制因素。暴露于一些环境应激因素被确定为增加OMV产生的水平以及AlgU（控制MucD表达的σ因子）的活性。AlgU的过表达被证明是足以诱导OMV的生产，但是，应力诱导的OMV的生产是不依赖于激活的AlgU，因为应力导致增加的囊泡形成缺乏algU的菌株。我们进一步确定MucD水平不是急性应激下OMV产生的指标，并且PQS不是应激或非应激条件下OMV产生所需的。最后，铜绿假单胞菌对氧化应激反应的研究表明，过氧化物诱导的OMV产生需要B带而不是A带脂多糖的存在。总之，这些结果表明，铜绿假单胞菌中存在不同的应激诱导OMV产生机制。
As an opportunistic Gram-negative pathogen, Pseudomonas aeruginosa must be able to adapt and survive changes and stressors in its environment during the course of infection. To aid survival in the hostile host environment, P. aeruginosa has evolved defense mechanisms, including the production of an exopolysaccharide capsule and the secretion of a myriad of degradative proteases and lipases. The production of outer membrane-derived vesicles (OMVs) serves as a secretion mechanism for virulence factors as well as a general bacterial response to envelope-acting stressors. This study investigated the effect of sublethal physiological stressors on OMV production by P. aeruginosa and whether the Pseudomonas quinolone signal (PQS) and the MucD periplasmic protease are critical mechanistic factors in this response. Exposure to some environmental stressors was determined to increase the level of OMV production as well as the activity of AlgU, the sigma factor that controls MucD expression. Overexpression of AlgU was shown to be sufficient to induce OMV production; however, stress-induced OMV production was not dependent on activation of AlgU, since stress caused increased vesiculation in strains lacking algU. We further determined that MucD levels were not an indicator of OMV production under acute stress, and PQS was not required for OMV production under stress or unstressed conditions. Finally, an investigation of the response of P. aeruginosa to oxidative stress revealed that peroxide-induced OMV production requires the presence of B-band but not A-band lipopolysaccharide. Together, these results demonstrate that distinct mechanisms exist for stress-induced OMV production in P. aeruginosa.