Differential Interactions of Piscidins with Phospholipids and Lipopolysaccharides at Membrane Interfaces
Differential Interactions of Piscidins with Phospholipids and Lipopolysaccharides at Membrane Interfaces
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DOI：
10.1021/acs.langmuir.0c00017
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发表时间：
2020-05-12
期刊：
影响因子：
3.9
通讯作者：
Sukharev, Sergei
中科院分区：
文献类型：
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作者：
Cetuk, Hannah;Maramba, Joseph;Sukharev, Sergei
鱼素1和3（P1和P3）是从条纹鲈鱼中分离的有效抗菌肽。它们的作用机制涉及在与磷脂接触时形成两亲性α-螺旋和使微生物细胞质膜不稳定。这些肽对革兰氏阳性和革兰氏阴性细菌都有活性，表明易于穿过外膜。在这里，我们进行了比较研究，这两个piscidin在空气-水界面上的脂多糖（LPS）单层建模外细菌表面的革兰氏阴性菌和磷脂单层，它模仿内膜。结果表明，P1和P3具有高度的表面活性（log K-AW近似为6.8），并与磷脂单层具有相似的亲和力（log K-lip近似为7.7）。P1对革兰氏阴性菌更有效，表现出更强的LPS单层分配（log K-LPS = 8.3）。压力-面积等温线表明，在侧压力增加的情况下，插入的P1从磷脂单层重新分配回到亚相或更浅的位置，平面内面积类似于170埃（2）/肽，对应于完全折叠的两亲性α-螺旋。相比之下，肽从LPS中排出的区域类似于35埃（2），这表明当肽贪婪地插入LPS分子之间时，它们可能不会形成类似取向的刚性二级结构。在大肠杆菌原生质球上的膜片钳实验表明，当P1和P3到达细菌细胞质膜的外表面时，它们在80 mV以上的电压下产生波动的导电结构。数据表明，这些piscidin对革兰氏阴性细菌的强活性始于肽在外LPS层中的优先积累，然后渗透到周质中，在周质中它们在与磷脂接触时形成稳定的两亲性α-螺旋并攻击通电的内膜。
Piscidins 1 and 3 (P1 and P3) are potent antimicrobial peptides isolated from striped bass. Their mechanism of action involves formation of amphipathic alpha-helices on contact with phospholipids and destabilization of the microbial cytoplasmic membrane. The peptides are active against both Gram-positive and Gram-negative bacteria, suggesting easy passage across the outer membrane. Here, we performed a comparative study of these two piscidins at the air-water interface on lipopolysaccharide (LPS) monolayers modeling the outer bacterial surface of Gram-negative organisms and on phospholipid monolayers, which mimic the inner membrane. The results show that P1 and P3 are highly surface active (log K-AW similar to 6.8) and have similar affinities to phospholipid monolayers (log K-lip approximate to 7.7). P1, which is more potent against Gram negatives, exhibits a much stronger partitioning into LPS monolayers (log K-LPS = 8.3). Pressure-area isotherms indicate that under increasing lateral pressures, inserted P1 repartitions from phospholipid monolayers back to the subphase or to a more shallow position with in-plane areas of similar to 170 angstrom(2) per peptide, corresponding to fully folded amphipathic alpha-helices. In contrast, peptide expulsion from LPS occurs with areas of similar to 35 angstrom(2), suggesting that the peptides may not form the similarly oriented, rigid secondary structures when they avidly intercalate between LPS molecules. Patch-clamp experiments on Escherichia coli spheroplasts show that when P1 and P3 reach the outer surface of the bacterial cytoplasmic membrane, they produce fluctuating conductive structures at voltages above 80 mV. The data suggests that the strong activity of these piscidins against Gram-negative bacteria begins with the preferential accumulation of peptides in the outer LPS layer followed by penetration into the periplasm, where they form stable amphipathic alpha-helices upon contact with phospholipids and attack the energized inner membrane.