Antimicrobial peptides (AMPs) appear as chemical compounds of increasing interest for their role in killing bacteria and, more recently, for their ability to bind endotoxin (lipopolysaccharide, LPS) that is released during bacterial infection and that may lead to septic shock. This dual role in the mechanism of action can further be enhanced in a synergistic way when two or more AMPs are combined together. Not all AMPs are able to bind LPS, suggesting that several modes of binding to the bacterial surface may exist. Here we analyze a natural AMP, crabrolin, and two mutated forms, one with increased positive charge (Crabrolin Plus) and the other with null charge (Crabrolin Minus), and compare their binding abilities to LPS. While Crabrolin WT as well Crabrolin Minus do not show binding to LPS, the mutated Crabrolin Plus exhibits binding and forms a well defined structure in the presence of LPS. The results strengthen the importance of positive charges for the binding to LPS and suggest the mutated form with increased positive charge as a promising candidate for antimicrobial and antiseptic activity.

中文翻译：

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正电荷对卡布罗林同工型与脂多糖的结构相互作用的影响。

抗菌肽（AMPs）以其在杀死细菌中的作用以及最近与细菌结合细菌感染期间释放的内毒素（脂多糖，LPS）的能力而引起越来越多的关注，它们可能导致败血性休克。当两个或多个AMP组合在一起时，可以以协同方式进一步增强作用机制中的双重作用。并非所有的AMP都能结合LPS，这表明可能存在与细菌表面结合的几种模式。在这里，我们分析了天然AMP，crabrolin和两种突变形式，一种具有增加的正电荷（Crabrolin Plus），另一种具有零电荷（Crabrolin Minus），并比较了它们与LPS的结合能力。尽管Crabrolin WT和Crabrolin Minus均未显示与LPS的结合，在LPS存在的情况下，突变的Crabrolin Plus表现出结合力，并形成了定义明确的结构。结果加强了正电荷对于与LPS结合的重要性，并表明具有增加的正电荷的突变形式是抗微生物和抗菌活性的有希望的候选者。