Abstract：
Lugdunin is a microbiome-derived antibacterial agent with good activity against Gram-positive pathogens in vitro and in animal models of nose colonization and skin infection. We have previously shown that lugdunin depletes bacterial energy resources by dissipating the membrane potential of Staphylococcus aureus. Here, we explored the mechanism of action of lugdunin in more detail and show that lugdunin quickly depolarizes cytoplasmic membranes of different bacterial species and acidifies the cytoplasm of S. aureus within minutes due to protonophore activity. Varying the salt species and concentrations in buffers revealed that not only protons are transported, and we demonstrate the binding of the monovalent cations K+, Na+, and Li+ to lugdunin. By comparing known ionophores with various ion transport mechanisms, we conclude that the ion selectivity of lugdunin largely resembles that of 15-mer linear peptide gramicidin A. Direct interference with the main bacterial metabolic pathways including DNA, RNA, protein, and cell wall biosyntheses can be excluded. The previously observed synergism of lugdunin with dermcidin-derived peptides such as DCD-1 in killing S. aureus is mechanistically based on potentiated membrane depolarization. We also found that lugdunin was active against certain eukaryotic cells, however strongly depending on the cell line and growth conditions. While adherent lung epithelial cell lines were almost unaffected, more sensitive cells showed dissipation of the mitochondrial membrane potential. Lugdunin seems specifically adapted to its natural environment in the respiratory tract. The ionophore mechanism is refractory to resistance development and benefits from synergy with host-derived antimicrobial peptides.
OBJECTIVE: The vast majority of antimicrobial peptides produced by members of the microbiome target the bacterial cell envelope by many different mechanisms. These compounds and their producers have evolved side-by-side with their host and were constantly challenged by the host\'s immune system. These molecules are optimized to be well tolerated at their physiological site of production, and their modes of action have proven efficient in vivo. Imbalancing the cellular ion homeostasis is a prominent mechanism among antibacterial natural products. For instance, over 120 naturally occurring polyether ionophores are known to date, and antimicrobial peptides with ionophore activity have also been detected in microbiomes. In this study, we elucidated the mechanism underlying the membrane potential-dissipating activity of the thiazolidine-containing cycloheptapeptide lugdunin, the first member of the fibupeptides discovered in a commensal bacterium from the human nose, which is a promising future probiotic candidate that is not prone to resistance development.
OBJECTIVE: The vast majority of antimicrobial peptides produced by members of the microbiome target the bacterial cell envelope by many different mechanisms. These compounds and their producers have evolved side-by-side with their host and were constantly challenged by the host\'s immune system. These molecules are optimized to be well tolerated at their physiological site of production, and their modes of action have proven efficient in vivo. Imbalancing the cellular ion homeostasis is a prominent mechanism among antibacterial natural products. For instance, over 120 naturally occurring polyether ionophores are known to date, and antimicrobial peptides with ionophore activity have also been detected in microbiomes. In this study, we elucidated the mechanism underlying the membrane potential-dissipating activity of the thiazolidine-containing cycloheptapeptide lugdunin, the first member of the fibupeptides discovered in a commensal bacterium from the human nose, which is a promising future probiotic candidate that is not prone to resistance development.
摘要：
Lugdunin是一种微生物组来源的抗菌剂，在体外和鼻子定植和皮肤感染的动物模型中具有良好的抗革兰氏阳性病原体活性。我们先前已经表明，lugdunin通过消散金黄色葡萄球菌的膜电位来消耗细菌能量资源。这里,我们更详细地探索了lugdunin的作用机理，并表明lugdunin迅速去极化不同细菌物种的细胞质膜，并由于质子载体活性在几分钟内酸化金黄色葡萄球菌的细胞质。改变缓冲液中的盐种类和浓度表明，不仅质子被运输，我们证明了单价阳离子K+的结合，Na+,和Li+到Lugdunin。通过将已知的离子载体与各种离子传输机制进行比较，我们得出的结论是，lugdunin的离子选择性在很大程度上类似于15-mer线性肽magicidinA的离子选择性。直接干扰主要的细菌代谢途径，包括DNA，RNA,蛋白质，和细胞壁生物合成可以排除。先前观察到的lugdunin与dermcidin衍生的肽如DCD-1在杀死金黄色葡萄球菌中的协同作用在机械上是基于增强的膜去极化。我们还发现lugdunin对某些真核细胞有活性，然而强烈依赖于细胞系和生长条件。虽然粘附的肺上皮细胞系几乎不受影响，更敏感的细胞显示线粒体膜电位的耗散。Lugdunin似乎特别适应其呼吸道的自然环境。离子载体机制难以产生抗性,并且受益于与宿主衍生的抗微生物肽的协同作用。
目的：微生物组成员产生的绝大多数抗菌肽通过许多不同的机制靶向细菌细胞包膜。这些化合物和它们的生产者已经与宿主并行进化，并不断受到宿主免疫系统的挑战。这些分子被优化为在其生理生产部位具有良好的耐受性，和它们的作用模式已被证明在体内是有效的。细胞离子稳态失衡是抗菌天然产物中的突出机制。例如,迄今为止，已知有超过120种天然存在的聚醚离子载体，在微生物组中也检测到具有离子载体活性的抗菌肽。在这项研究中,我们阐明了含噻唑烷的环七肽lugdunin的膜电位消散活性的潜在机制，在人类鼻子的共生细菌中发现的第一个纤维肽成员，这是一个有希望的未来益生菌候选，不容易产生耐药性。
目的：微生物组成员产生的绝大多数抗菌肽通过许多不同的机制靶向细菌细胞包膜。这些化合物和它们的生产者已经与宿主并行进化，并不断受到宿主免疫系统的挑战。这些分子被优化为在其生理生产部位具有良好的耐受性，和它们的作用模式已被证明在体内是有效的。细胞离子稳态失衡是抗菌天然产物中的突出机制。例如,迄今为止，已知有超过120种天然存在的聚醚离子载体，在微生物组中也检测到具有离子载体活性的抗菌肽。在这项研究中,我们阐明了含噻唑烷的环七肽lugdunin的膜电位消散活性的潜在机制，在人类鼻子的共生细菌中发现的第一个纤维肽成员，这是一个有希望的未来益生菌候选，不容易产生耐药性。
