Brackman Gilles, Defoirdt Tom, Miyamoto Carol, Bossier Peter, Van Calenbergh Serge, Nelis Hans, Coenye Tom
Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium.
BMC Microbiol. 2008 Sep 16;8:149. doi: 10.1186/1471-2180-8-149.
To date, only few compounds targeting the AI-2 based quorum sensing (QS) system are known. In the present study, we screened cinnamaldehyde and substituted cinnamaldehydes for their ability to interfere with AI-2 based QS. The mechanism of QS inhibition was elucidated by measuring the effect on bioluminescence in several Vibrio harveyi mutants. We also studied in vitro the ability of these compounds to interfere with biofilm formation, stress response and virulence of Vibrio spp. The compounds were also evaluated in an in vivo assay measuring the reduction of Vibrio harveyi virulence towards Artemia shrimp.
Our results indicate that cinnamaldehyde and several substituted derivatives interfere with AI-2 based QS without inhibiting bacterial growth. The active compounds neither interfered with the bioluminescence system as such, nor with the production of AI-2. Study of the effect in various mutants suggested that the target protein is LuxR. Mobility shift assays revealed a decreased DNA-binding ability of LuxR. The compounds were further shown to (i) inhibit biofilm formation in several Vibrio spp., (ii) result in a reduced ability to survive starvation and antibiotic treatment, (iii) reduce pigment and protease production in Vibrio anguillarum and (iv) protect gnotobiotic Artemia shrimp against virulent Vibrio harveyi BB120.
Cinnamaldehyde and cinnamaldehyde derivatives interfere with AI-2 based QS in various Vibrio spp. by decreasing the DNA-binding ability of LuxR. The use of these compounds resulted in several marked phenotypic changes, including reduced virulence and increased susceptibility to stress. Since inhibitors of AI-2 based quorum sensing are rare, and considering the role of AI-2 in several processes these compounds may be useful leads towards antipathogenic drugs.
迄今为止，已知仅有少数几种化合物可靶向基于自诱导物-2（AI-2）的群体感应（QS）系统。在本研究中，我们筛选了肉桂醛及取代肉桂醛干扰基于AI-2的QS的能力。通过测定对几种哈维氏弧菌突变体生物发光的影响，阐明了QS抑制机制。我们还在体外研究了这些化合物干扰弧菌属生物膜形成、应激反应和毒力的能力。这些化合物还通过体内试验进行评估，该试验测定哈维氏弧菌对卤虫虾毒力的降低情况。
我们的结果表明，肉桂醛和几种取代衍生物可干扰基于AI-2的QS，而不抑制细菌生长。活性化合物既不干扰生物发光系统本身，也不干扰AI-2的产生。对各种突变体的效应研究表明，靶蛋白是LuxR。迁移率变动分析显示LuxR的DNA结合能力降低。这些化合物还进一步显示出：（i）抑制几种弧菌属的生物膜形成；（ii）导致饥饿和抗生素处理下的存活能力降低；（iii）减少鳗弧菌中色素和蛋白酶的产生；（iv）保护无菌卤虫虾免受强毒哈维氏弧菌BB120的侵害。
肉桂醛和肉桂醛衍生物通过降低LuxR的DNA结合能力，干扰各种弧菌属中基于AI-2的QS。这些化合物的使用导致了几种显著的表型变化，包括毒力降低和应激敏感性增加。由于基于AI-2的群体感应抑制剂很少见，并且考虑到AI-2在多个过程中的作用，这些化合物可能是开发抗病原体药物的有用先导物。
