Structure and organization of hemolytic and nonhemolytic diastereomers of antimicrobial peptides in membranes
Structure and organization of hemolytic and nonhemolytic diastereomers of antimicrobial peptides in membranes
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DOI：
10.1021/bi991850y
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发表时间：
1999-12-21
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：
Hong, J;Oren, Z;Shai, Y
最近，我们报道了一组新的由不同比例的亮氨酸和赖氨酸组成的短模式多肽(12个氨基酸长)的非对映异构体，它们具有一些性质，使它们有可能比天然或新设计的所有L氨基酸抗菌肽更好。初步研究表明，调节这些非对映异构体的疏水性和正电荷足以赋予抗菌活性和细胞选择性。然而，它们的生物学功能、结构和作用方式之间的关系还没有被研究。在这里，我们合成并研究了三种线性模型非对映异构体(12个氨基酸长)，它们具有不同的赖氨酸：亮氨酸(或色氨酸)比例(即K3L8W、K5L6W和K7L4W)，它们具有不同水平的裂解活性。对于每个K：L比，色氨酸被引入到多肽的中间或N-端或C-端，作为本征荧光探针。只有溶血肽K3L8W与带负电荷和两性离子的磷脂膜结合。K5L6W和K7L4W类似，但只与带负电的膜结合，尽管K5L6W比K7L4W对细菌的裂解能力要强得多。有趣的是，虽然K3L8W含有33%的D-氨基酸，但ATR-FTIR光谱显示两种膜的结构都类似于90%的α-螺旋。此外，K5L6W含有类似于40%的3(10)-螺旋，而K7L4W主要是膜中的无规卷曲。用溴化磷脂进行的极化ATR-FTIR和色氨酸猝灭实验表明，所有多肽的穿透深度和取向都是平行于膜表面的，但K3L8W对脂质顺序的影响比其他多肽更大。这些结果为深入了解这组非对映异构体多肽的作用方式，以及疏水性和正电荷对其膜结构、功能和细胞选择性的影响提供了深入的了解。此外，这项研究应该有助于开发合适的非对映异构体多肽抗生素用于治疗，以克服细菌对常规抗生素耐药性增加的问题。
Recently, we reported on a new group of diastereomers of short-model peptides (12 amino acids long) composed of leucine and lysine with varying ratios, possessing several properties that make them potentially better than native or de novo-designed all L-amino acid antimicrobial peptides. Preliminary studies have revealed that modulating the hydrophobicity and positive charges of these diastereomers is sufficient to confer antibacterial activity and cell selectivity. However, the relationship between their biological function, structure, and mode of action was not investigated. Here we synthesized and investigated three types of linear model diastereomers (12 amino acids long) with varying lysine:leucine (or tryptophan) ratios (i.e., K3L8W, K5L6W, and K7L4W), which confer different levels of lytic activities. For each K:L ratio, tryptophan was introduced in the middle or the N- or C-terminus of the peptides, as an intrinsic fluorescent probe. Only the hemolytic peptide K3L8W binds to both negatively charged and zwitterionic phospholipid membranes. K5L6W and K7L4W bind similarly, but only to negatively charged membranes, despite the fact that K5L6W is substantially more lytic to bacteria than K7L4W. Interestingly, although K3L8W contains 33% D-amino acids, ATR-FTIR spectroscopy revealed a structure of similar to 90% alpha-helix in both types of membranes. In addition, K5L6W contains similar to 40% 3(10)-helix and K7L4W is predominantly a random coil in membranes. Polarized ATR-FTIR and tryptophan-quenching experiments, using brominated phospholipids, revealed a similar depth of penetration and an orientation that was parallel to the membrane surface for all the peptides, but with K3L8W affecting the lipid order more than the others. The results provide insight into the mode of action of this group of diastereomeric peptides, and the effect of hydrophobicity and positive charges on their membrane structure, function, and cell selectivity. Moreover, this research should assist in the development of suitable diastereomeric peptide antibiotics for therapeutic use that would overcame the problem the increasing resistance of bacteria to conventional antibiotics.