Edwards-Gayle Charlotte J C, Barrett Glyn, Roy Shyamali, Castelletto Valeria, Seitsonen Jani, Ruokolainen Janne, Hamley Ian W
School of Chemistry, Pharmacy and Food Biosciences, University of Reading, Whiteknights, Reading RG6 6AD, U.K.
School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6AD, U.K.
ACS Appl Bio Mater. 2020 Feb 17;3(2):1165-1175. doi: 10.1021/acsabm.9b00894. Epub 2020 Jan 21.
The self-assembly behavior and antimicrobial activity of two designed amphiphilic peptides, RF and RF, containing short hydrophobic phenylalanine (F) and cationic arginine (R) sequences, are investigated. The conformation of the peptides was examined using circular dichroism and FTIR spectroscopy, which show that they have a disordered secondary structure. Concentration-dependent fluorescence assays show the presence of a critical aggregation concentration (cac) for each peptide. Above the cac, small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) reveal a population of twisted tapes for RF and nanosheets for RF. The interaction of the peptides with model bacterial membranes comprising mixtures of the lipids DPPG [1,2-dipalmitoyl--glycero-3-phosphoglycerol] and DPPE [1,2-dipalmitoyl--glycero-3-phosphoethanolamine], was studied using SAXS and cryogenic-TEM. Analysis of the SAXS structure factor indicates that RF interacts with lipid bilayers by inducing correlation between bilayers, whereas RF interacts with the bilayers causing an increase in polydispersity of the vesicle wall thickness. Both peptides break vesicles with a 1:3 DPPG:DPPE composition, which is close to the ratio of PG and PE lipids observed in the lipid membrane of , a pathogen responsible for serious infections and which has developed antimicrobial resistant strains. Both peptides show activity against this bacterium in planktonic form. Peptide RF shows particularly strong bioactivity against this microbe, with a minimum inhibitory concentration (MIC) value in the range of concentrations where the peptide is cytocompatible. It was further shown to have activity against other s species including the common plant pathogen . Finally, we show that RF inhibits the development of biofilms. This was examined in detail and a proposed mechanism involving binding of the signaling molecule c-di-GMP is suggested, based on circular dichroism spectroscopy studies and Congo red assays of extracellular polysaccharides produced by the stressed bacteria. Thus, RF is a promising candidate antimicrobial peptide with activity against species.
研究了两种设计的两亲性肽RF和RF的自组装行为及抗菌活性，这两种肽含有短的疏水性苯丙氨酸（F）和阳离子精氨酸（R）序列。使用圆二色性和傅里叶变换红外光谱对肽的构象进行了检测，结果表明它们具有无序的二级结构。浓度依赖性荧光测定表明每种肽都存在临界聚集浓度（cac）。高于cac时，小角X射线散射（SAXS）和透射电子显微镜（TEM）显示RF形成扭曲带，RF形成纳米片。使用SAXS和低温TEM研究了肽与由脂质DPPG [1,2 - 二棕榈酰 - sn -甘油 - 3 - 磷酸甘油]和DPPE [1,2 - 二棕榈酰 - sn -甘油 - 3 - 磷酸乙醇胺]混合物组成的模型细菌膜的相互作用。对SAXS结构因子的分析表明，RF通过诱导双层之间的相关性与脂质双层相互作用，而RF与双层相互作用导致囊泡壁厚度的多分散性增加。两种肽都能破坏具有1:3 DPPG:DPPE组成的囊泡，该比例接近在一种导致严重感染且已产生抗菌耐药菌株的病原体的脂质膜中观察到的PG和PE脂质的比例。两种肽对这种浮游形式的细菌都有活性。肽RF对这种微生物表现出特别强的生物活性，其最小抑菌浓度（MIC）值处于该肽具有细胞相容性的浓度范围内。进一步表明它对包括常见植物病原体在内的其他物种也有活性。最后，我们表明RF抑制生物膜的形成。对此进行了详细研究，并基于圆二色性光谱研究和对受胁迫细菌产生的细胞外多糖的刚果红测定，提出了一种涉及信号分子c - 二鸟苷酸结合的机制。因此，RF是一种有前景的抗微生物肽，对物种具有活性。
