Selective lysis of bacteria but not mammalian cells by diastereomers of melittin: Structure-function study
Selective lysis of bacteria but not mammalian cells by diastereomers of melittin: Structure-function study
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DOI：
10.1021/bi962507l
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发表时间：
1997-02-18
期刊：
影响因子：
2.9
通讯作者：
Shai, Y
中科院分区：
文献类型：
--
作者：
Oren, Z;Shai, Y
对溶细胞多肽的脂肽相互作用的研究倾向于强调两亲性α-螺旋结构对其溶细胞活性的重要性。在这项研究中，蜂毒蜂毒肽（26 a.a.），合成了一种非细胞选择性溶细胞素，并研究了其结构和对细菌和哺乳动物细胞的溶细胞活性。类似于对较小细胞溶解肽帕达辛（33 a.a.）(Shai& Oren，1996），蜂毒肽非对映异构体失去了它们的α-螺旋结构，这消除了它们对人红细胞的溶血活性。然而，它们保留了它们的抗菌活性，并完全裂解革兰氏阳性和革兰氏阴性细菌，如透射电子显微镜所示。为了理解这种选择性的分子机制，结合实验利用蜂毒素的固有色氨酸，色氨酸淬灭实验，使用溴化磷脂，和膜去稳定化的研究。数据显示，蜂毒肽的非对映异构体绑定到和不稳定的只有带负电荷的磷脂囊泡，与天然蜂毒肽，强烈结合到带负电荷的和两性离子的磷脂。然而，分配系数，渗透到膜的深度，和膜渗透活性的非对映体与带负电荷的磷脂是类似的蜂毒肽。所获得的结果不支持跨膜孔的形成作为非对映异构体的作用模式，而是表明这些肽结合到细菌膜的表面，以“地毯样”方式覆盖它，并像洗涤剂一样溶解它。这里呈现的结果连同用溶细胞肽pardaxin获得的那些结果表明，疏水性和净正电荷的组合可能足以设计用于治疗感染性疾病的抗菌多肽的有效非对映体。
Studies on lipid-peptide interactions of cytolytic polypeptides tend to emphasize the importance of the amphipathic alpha-helical structure for their cytolytic activity. In this study, diasetereomers of the bee venom melittin (26 a.a.), a non-cell-selective cytolysin, were synthesized and investigated for their structure and cytolytic activity toward bacteria and mammalian cells. Similarly to the findings with the diastereomers of the less cytolytic peptide pardaxin (33 a.a.) (Shai & Oren, 1996), the melittin diastereomers lost their alpha-helical structure, which abrogated their hemolytic activity toward human erythrocytes. However, they retained their antibacterial activity and completely lysed both Gram-positive and Gram-negative bacteria, as revealed by transmission electron microscopy. To understand the molecular mechanism underlying this selectivity, binding experiments utilizing the intrinsic tryptophan of melittin, tryptophan quenching experiments using brominated phospholipids, and membrane destabilization studies were done. The data revealed that the melittin diastereomers bound to and destabilized only negatively-charged phospholipid vesicles, in contrast to native melittin, which binds strongly to both negatively-charged and zwitterionic phospholipids. However, the partition coefficient, the depth of penetration into the membrane, and the membrane-permeating activity of the diastereomers with negatively-charged phospholipids were similar to those obtained with melittin. The results obtained do not support the formation of transmembrane pores as the mode of action of the diastereomers, but rather suggest that these peptides bind to the surface of the bacterial membrane, cover it in a ''carpet-like'' manner, and dissolve it like a detergent. The results presented here together with those obtained with the cytolytic peptide pardaxin suggest that the combination of hydrophobicity and net positive charge may be sufficient in the design of potent diastereomers of antibacterial polypeptides for the treatment of infectious diseases.