Wang Huanhuan, Kraus Frank, Popella Peter, Baykal Aslihan, Guttroff Claudia, François Patrice, Sass Peter, Plietker Bernd, Götz Friedrich
Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), University of Tübingen, Tübingen, Germany.
Institut für Organische Chemie, Universität Stuttgart, Stuttgart, Germany.
Front Microbiol. 2019 Jan 22;10:14. doi: 10.3389/fmicb.2019.00014. eCollection 2019.
Recently, a series of endo-type B polycyclic polyprenylated acylphloroglucinols (PPAP) derivatives with high antimicrobial activities were chemically synthesized. One of the derivatives, PPAP 23, which showed high antimicrobial activity and low cytotoxicity, was chosen for further investigation of its bactericidal profiles and mode of action. PPAP 23 showed a better efficacy in killing methicillin resistant (MRSA) and decreasing the metabolic activity of 5-day-old biofilm cells than vancomycin. Moreover, did not appear to develop resistance against PPAP 23. The antimicrobial mechanism of PPAP 23 was investigated by RNA-seq combined with phenotypic and biochemical approaches. RNA-seq suggested that PPAP 23 signaled iron overload to the bacterial cells because genes involved in iron transport were downregulated and iron storage gene was upregulated by PPAP 23. PPAP 23 affected the membrane integrity but did not induce pore formation; it inhibited bacterial respiration. PPAP 23 preferentially inhibited Fe-S cluster enzymes; it has a mild iron chelating activity and supplementation of exogenous iron attenuated its antimicrobial activity. PPAP 23 was more effective in inhibiting the growth of under iron-restricted condition. The crystal structure of a benzylated analog of PPAP 23 showed a highly defined octahedral coordination of three PPAP ligands around a Fe (3+) core. This suggests that PPAPs are generally capable of iron chelation and are able to form defined stable complexes. PPAP 23 was found to induce reactive oxygen species (ROS) and oxidative stress. Fluorescence microscopic analysis showed that PPAP 23 caused an enlargement of the bacterial cells, perturbed the membrane, and dislocated the nucleoid. Taken together, we postulate that PPAP 23 interacts with the cytoplasmic membrane with its hydrophobic pocket and interferes with the iron metabolism to exert its antimicrobial activity in .
最近，一系列具有高抗菌活性的内型B多环多异戊烯基酰基间苯三酚（PPAP）衍生物被化学合成出来。其中一种衍生物PPAP 23表现出高抗菌活性和低细胞毒性，因此被选来进一步研究其杀菌谱和作用方式。与万古霉素相比，PPAP 23在杀死耐甲氧西林金黄色葡萄球菌（MRSA）以及降低5日龄生物膜细胞的代谢活性方面表现出更好的效果。此外，似乎没有对PPAP 23产生抗性。通过RNA测序结合表型和生化方法研究了PPAP 23的抗菌机制。RNA测序表明，PPAP 23向细菌细胞发出铁过载信号，因为参与铁转运的基因被PPAP 23下调，而铁储存基因被上调。PPAP 23影响膜的完整性，但不诱导孔形成；它抑制细菌呼吸。PPAP 23优先抑制铁硫簇酶；它具有温和的铁螯合活性，补充外源铁会减弱其抗菌活性。PPAP 23在铁限制条件下更有效地抑制细菌生长。PPAP 23的一种苄基化类似物的晶体结构显示，在Fe（3+）核心周围有三个PPAP配体形成高度明确的八面体配位。这表明PPAP通常能够进行铁螯合并能够形成明确的稳定复合物。发现PPAP 23会诱导活性氧（ROS）和氧化应激。荧光显微镜分析表明，PPAP 23导致细菌细胞肿大、扰乱膜结构并使类核移位。综上所述，我们推测PPAP 23通过其疏水口袋与细胞质膜相互作用，并干扰铁代谢以在细菌中发挥其抗菌活性。
