Effects of Signal Disruption Depends on the Substrate Preference of the Lactonase
Effects of Signal Disruption Depends on the Substrate Preference of the Lactonase
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DOI：
10.3389/fmicb.2019.03003
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发表时间：
2020-01-14
影响因子：
5.2
通讯作者：
Elias, Mikael
中科院分区：
文献类型：
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作者：
Mahan, Kathleen;Martinmaki, Ryan;Elias, Mikael
许多细菌产生和使用细胞外信号分子，如酰基高丝氨酸内酯(AHLS)，通过一种称为群体感应(QS)的通信系统，以细胞密度依赖的方式进行沟通和协调行为。该系统调节行为，包括但不限于毒力和生物膜的形成。我们专注于铜绿假单胞菌，这是一种人类机会病原体，与急性和慢性肺部感染有关，对囊性纤维化患者的影响不成比例。随着抗生素耐药性的传播，铜绿假单胞菌感染的治疗变得越来越困难。因此，被称为群体猝灭的QS中断方法因其控制耐药菌株毒力的潜力而受到人们的青睐。有趣的是，已知铜绿假单胞菌同时利用两个主要的QS回路，一个基于C4-AHL，另一个基于3-oxo-C12-AHL。在这里，我们评估了信号干扰对39株囊性纤维化铜绿假单胞菌临床分离株的影响，包括耐药菌株。我们使用了两种能够降解AHL的酶，称为内酯酶，具有不同的底物偏好：一种降解3-oxo-C12-AHL，另一种同时降解C4-AHL和3-oxo-C12-AHL。两种内酰胺酶被用来确定信号干扰对临床分离株的影响，并通过测量对毒力因子(弹性酶、蛋白酶和绿青素)和生物被膜形成的影响来评估QS回路的重要性。信号中断导致大多数分离物(92%)至少其中一个因子被抑制。毒力因子活性或产量被抑制高达100%，生物被膜平均被抑制2.3倍。值得注意的是，这些处理导致了不同的菌株的抑制谱；用降解两个信号分子的乳糖酶处理导致了更高比例的抑制菌株(77%比67%)，并同时抑制了每个菌株更多的毒力因子(2vs.1.5)。这一发现表明，乳糖酶AHL的偏好是其抑制谱的关键，也是改进群体猝灭策略的关键参数。
Many bacteria produce and use extracellular signaling molecules such as acyl homoserine lactones (AHLs) to communicate and coordinate behavior in a cell-density dependent manner, via a communication system called quorum sensing (QS). This system regulates behaviors including but not limited to virulence and biofilm formation. We focused on Pseudomonas aeruginosa, a human opportunistic pathogen that is involved in acute and chronic lung infections and which disproportionately affects people with cystic fibrosis. P. aeruginosa infections are becoming increasingly challenging to treat with the spread of antibiotic resistance. Therefore, QS disruption approaches, known as quorum quenching, are appealing due to their potential to control the virulence of resistant strains. Interestingly, P. aeruginosa is known to simultaneously utilize two main QS circuits, one based on C4-AHL, the other with 3-oxo-C12-AHL. Here, we evaluated the effects of signal disruption on 39 cystic fibrosis clinical isolates of P. aeruginosa, including drug resistant strains. We used two enzymes capable of degrading AHLs, known as lactonases, with distinct substrate preference: one degrading 3-oxo-C12-AHL, the other degrading both C4-AHL and 3-oxo-C12-AHL. Two lactonases were used to determine the effects of signal disruption on the clinical isolates, and to evaluate the importance of the QS circuits by measuring effects on virulence factors (elastase, protease, and pyocyanin) and biofilm formation. Signal disruption results in at least one of these factors being inhibited for most isolates (92%). Virulence factor activity or production were inhibited by up to 100% and biofilm was inhibited by an average of 2.3 fold. Remarkably, the treatments led to distinct inhibition profiles of the isolates; the treatment with the lactonase degrading both signaling molecules resulted in a higher fraction of inhibited isolates (77% vs. 67%), and the simultaneous inhibition of more virulence factors per strain (2 vs. 1.5). This finding suggests that the lactonase AHL preference is key to its inhibitory spectrum and is an essential parameter to improve quorum quenching strategies.