Rahnamaeian Mohammad, Cytryńska Małgorzata, Zdybicka-Barabas Agnieszka, Dobslaff Kristin, Wiesner Jochen, Twyman Richard M, Zuchner Thole, Sadd Ben M, Regoes Roland R, Schmid-Hempel Paul, Vilcinskas Andreas
Department of Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology, Winchester Strasse 2, Giessen 35394, Germany.
Department of Immunobiology, Institute of Biology and Biochemistry, Maria Curie-Sklodowska University, Akademicka Street 19, Lublin 20-033, Poland.
Proc Biol Sci. 2015 May 7;282(1806):20150293. doi: 10.1098/rspb.2015.0293.
Antimicrobial peptides (AMPs) and proteins are important components of innate immunity against pathogens in insects. The production of AMPs is costly owing to resource-based trade-offs, and strategies maximizing the efficacy of AMPs at low concentrations are therefore likely to be advantageous. Here, we show the potentiating functional interaction of co-occurring insect AMPs (the bumblebee linear peptides hymenoptaecin and abaecin) resulting in more potent antimicrobial effects at low concentrations. Abaecin displayed no detectable activity against Escherichia coli when tested alone at concentrations of up to 200 μM, whereas hymenoptaecin affected bacterial cell growth and viability but only at concentrations greater than 2 μM. In combination, as little as 1.25 μM abaecin enhanced the bactericidal effects of hymenoptaecin. To understand these potentiating functional interactions, we investigated their mechanisms of action using atomic force microscopy and fluorescence resonance energy transfer-based quenching assays. Abaecin was found to reduce the minimal inhibitory concentration of hymenoptaecin and to interact with the bacterial chaperone DnaK (an evolutionarily conserved central organizer of the bacterial chaperone network) when the membrane was compromised by hymenoptaecin. These naturally occurring potentiating interactions suggest that combinations of AMPs could be used therapeutically against Gram-negative bacterial pathogens that have acquired resistance to common antibiotics.
抗菌肽（AMPs）和蛋白质是昆虫抵御病原体的固有免疫的重要组成部分。由于基于资源的权衡，AMPs的产生成本高昂，因此在低浓度下最大化AMPs功效的策略可能具有优势。在这里，我们展示了同时存在的昆虫AMPs（大黄蜂线性肽膜翅目杀菌肽和阿贝辛）之间的增强功能相互作用，从而在低浓度下产生更强的抗菌效果。单独测试时，浓度高达200μM的阿贝辛对大肠杆菌没有可检测到的活性，而膜翅目杀菌肽仅在浓度大于2μM时才会影响细菌细胞的生长和活力。两者结合时，低至1.25μM的阿贝辛就能增强膜翅目杀菌肽的杀菌效果。为了理解这些增强功能的相互作用，我们使用原子力显微镜和基于荧光共振能量转移的猝灭分析来研究它们的作用机制。当膜被膜翅目杀菌肽破坏时，发现阿贝辛会降低膜翅目杀菌肽的最低抑菌浓度，并与细菌伴侣蛋白DnaK（细菌伴侣蛋白网络中进化保守的核心组织者）相互作用。这些天然存在的增强相互作用表明，AMPs的组合可用于治疗已对常用抗生素产生耐药性的革兰氏阴性细菌病原体。
