Antimicrobial peptides are a large group of natural compounds which present promising properties for the pharmaceutical and food industries, such as broad-spectrum activity, potential for use as natural preservatives, and reduced propensity for development of bacterial resistance. Plantaricin 149 (Pln149), isolated from Lactobacillus plantarum NRIC 149, is an intrinsically disordered peptide with the ability to inhibit bacteria from the Listeria and Staphylococcus genera, and which is capable of promoting inhibition and disruption of yeast cells. In this study, the interactions of Pln149 with model membranes composed of zwitterionic and/or anionic phospholipids were investigated using a range of biophysical techniques, including isothermal titration calorimetry, surface tension measurements, synchrotron radiation circular dichroism spectroscopy, oriented circular dichroism spectroscopy, and optical microscopy, to elucidate these peptides' mode of interactions and provide insight into their functional roles. In anionic model membranes, the binding of Pln149 to lipid bilayers is an endothermic process and induces a helical secondary structure in the peptide. The helices bind parallel to the surfaces of lipid bilayers and can promote vesicle disruption, depending on peptide concentration. Although Pln149 has relatively low affinity for zwitterionic liposomes, it is able to adsorb at their lipid interfaces, disturbing the lipid packing, assuming a similar parallel helix structure with a surface-bound orientation, and promoting an increase in the membrane surface area. Such findings can explain the intriguing inhibitory action of Pln149 in yeast cells whose cell membranes have a significant zwitterionic lipid composition.

中文翻译：

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在两性离子和带负电荷的膜中揭示抗菌肽Plantaricin 149的结合和方向。

抗菌肽是一大类天然化合物，它们在制药和食品工业中展现出令人鼓舞的特性，例如广谱活性，用作天然防腐剂的潜力以及降低的细菌抗药性。从植物乳杆菌NRIC 149中分离出来的Plantaricin 149（Pln149）是一种内在失调的肽，具有抑制利斯特氏菌和葡萄球菌属细菌的能力，并且能够促进酵母细胞的抑制和破坏。在这项研究中，Pln149与由两性离子和/或阴离子磷脂组成的模型膜的相互作用已通过一系列生物物理技术进行了研究，包括等温滴定量热法，表面张力测量，同步辐射圆二色谱，定向圆二色光谱和光学显微镜，以阐明这些肽的相互作用方式，并深入了解其功能作用。在阴离子模型膜中，Pln149与脂质双层的结合是一个吸热过程，并在肽中诱导出螺旋二级结构。螺旋与脂双层的表面平行结合，并可以根据肽浓度促进囊泡破坏。尽管Pln149对两性离子脂质体的亲和力较低，但它能够吸附在其脂质界面上，从而破坏脂质堆积，并假定具有表面结合方向的类似平行螺旋结构并促进膜表面积的增加。