Chrom Christina L, Renn Lindsay M, Caputo Gregory A
Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA.
Department of Molecular and Cellular Biosciences, Rowan University, Glassboro, NJ 08028, USA.
Antibiotics (Basel). 2019 Mar 6;8(1):20. doi: 10.3390/antibiotics8010020.
The continued emergence of new antibiotic resistant bacterial strains has resulted in great interest in the development of new antimicrobial treatments. Antimicrobial peptides (AMPs) are one of many potential classes of molecules to help meet this emerging need. AMPs are naturally derived sequences, which act as part of the innate immune system of organisms ranging from insects through humans. We investigated the antimicrobial peptide AP3, which is originally isolated from the winter flounder . This peptide is of specific interest because it does not exhibit the canonical facially amphiphilic orientation of side chains when in a helical orientation. Different analogs of AP3 were synthesized in which length, charge identity, and Trp position were varied to investigate the sequence-structure and activity relationship. We performed biophysical and microbiological characterization using fluorescence spectroscopy, CD spectroscopy, vesicle leakage assays, bacterial membrane permeabilization assays, and minimal inhibitory concentration (MIC) assays. Fluorescence spectroscopy showed that the peptides bind to lipid bilayers to similar extents, while CD spectra show the peptides adopt helical conformations. All five peptides tested in this study exhibited binding to model lipid membranes, while the truncated peptides showed no measurable antimicrobial activity. The most active peptide proved to be the parent peptide AP3 with the highest degree of leakage and bacterial membrane permeabilization. Moreover, it was found that the ability to permeabilize model and bacterial membranes correlated most closely with the ability to predict antimicrobial activity.
新的抗生素耐药细菌菌株不断出现，这引发了人们对开发新型抗菌治疗方法的极大兴趣。抗菌肽（AMPs）是众多有望满足这一新兴需求的潜在分子类别之一。AMPs是天然衍生的序列，作为从昆虫到人类等生物体固有免疫系统的一部分发挥作用。我们研究了最初从冬季比目鱼中分离出的抗菌肽AP3。这种肽特别令人感兴趣，因为它在呈螺旋取向时不表现出典型的侧链表面两亲性取向。合成了AP3的不同类似物，其中长度、电荷特性和色氨酸位置各不相同，以研究序列 - 结构与活性的关系。我们使用荧光光谱、圆二色光谱、囊泡泄漏测定、细菌膜通透性测定和最低抑菌浓度（MIC）测定进行了生物物理和微生物学表征。荧光光谱表明，这些肽与脂质双层的结合程度相似，而圆二色光谱显示这些肽呈现螺旋构象。本研究中测试的所有五种肽都表现出与模型脂质膜的结合，而截短的肽没有可测量的抗菌活性。活性最高的肽被证明是母肽AP3，其具有最高程度的泄漏和细菌膜通透性。此外，发现通透模型膜和细菌膜的能力与预测抗菌活性的能力最密切相关。
