Sani Marc-Antoine, Carne Siobhan, Overall Sarah A, Poulhazan Alexandre, Separovic Frances
School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia.
Universite Pierre et Marie Curie (Paris VI), 4 Place Jussieu, 75252, Paris Cedex 5, France.
Eur Biophys J. 2017 Oct;46(7):639-646. doi: 10.1007/s00249-017-1215-9. Epub 2017 May 6.
Antimicrobial peptides (AMPs) may act by targeting the lipid membranes and disrupting the bilayer structure. In this study, three AMPs from the skin of Australian tree frogs, aurein 1.2, maculatin 1.1 and caerin 1.1, were investigated against Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and vesicles that mimic their lipid compositions. Furthermore, equimolar mixtures of the peptides were tested to identify any synergistic interactions in antimicrobial activity. Minimum inhibition concentration and minimum bactericidal concentration assays showed significant activity against S. aureus but not against E. coli. Aurein was the least active while maculatin was the most active peptide and some synergistic effects were observed against S. aureus. Circular dichroism experiments showed that, in the presence of phospholipid vesicles, the peptides transitioned from an unstructured to a predominantly helical conformation (>50%), with greater helicity for POPG/TOCL compared to POPE/POPG vesicles. The helical content, however, was less in the presence of live E. coli and S. aureus, 25 and 5%, respectively. Equimolar concentrations of the peptides did not appear to form greater supramolecular structures. Dye release assays showed that aurein required greater concentration than caerin and maculatin to disrupt the lipid bilayers, and mixtures of the peptides did not cooperate to enhance their lytic activity. Overall, aurein, maculatin, and caerin showed moderate synergy in antimicrobial activity against S. aureus without becoming more structured or enhancement of their membrane-disrupting activity in phospholipid vesicles.
抗菌肽（AMPs）可能通过靶向脂质膜并破坏双层结构来发挥作用。在本研究中，对来自澳大利亚树蛙皮肤的三种抗菌肽——奥瑞因1.2、黄斑蛙素1.1和凯林1.1，针对革兰氏阴性大肠杆菌、革兰氏阳性金黄色葡萄球菌以及模拟其脂质组成的囊泡进行了研究。此外，还测试了这些肽的等摩尔混合物，以确定抗菌活性中是否存在任何协同相互作用。最低抑菌浓度和最低杀菌浓度测定表明，这些肽对金黄色葡萄球菌具有显著活性，但对大肠杆菌没有活性。奥瑞因活性最低，而黄斑蛙素是活性最高的肽，并且观察到对金黄色葡萄球菌有一些协同作用。圆二色性实验表明，在磷脂囊泡存在的情况下，这些肽从无结构转变为主要呈螺旋构象（>50%），与磷脂酰乙醇胺/磷脂酰甘油（POPE/POPG）囊泡相比，在1-棕榈酰-2-油酰-sn-甘油-3-磷酸甘油/氯化十八烷基三甲基铵（POPG/TOCL）囊泡中螺旋度更高。然而，在活的大肠杆菌和金黄色葡萄球菌存在的情况下，螺旋含量分别较低，为25%和5%。等摩尔浓度的肽似乎没有形成更大的超分子结构。染料释放试验表明，与凯林和黄斑蛙素相比，奥瑞因需要更高的浓度才能破坏脂质双层，并且肽的混合物没有协同增强它们的裂解活性。总体而言，奥瑞因、黄斑蛙素和凯林在对金黄色葡萄球菌的抗菌活性方面表现出适度的协同作用，在磷脂囊泡中没有变得更有结构或增强其膜破坏活性。
