Peptide Chemistry Laboratory, Institute of Biochemistry and Biophysics, University of Tehran, 16 Azar Street, 14176-14335 Tehran, Iran.
Peptide-Lipid Interaction, Department of Chemical Biology, Leibniz Institute of Molecular Pharmacology, Robert-Roessle-Strasse 10, 13125 Berlin, Germany.
ACS Appl Mater Interfaces. 2020 Jun 17;12(24):26852-26867. doi: 10.1021/acsami.0c04336. Epub 2020 Jun 5.
The influence of side chain residue and phospholipid characteristics of the cytoplasmic membrane upon the fibrillation and bacterial aggregation of arginine (Arg) and tryptophan (Trp) rich antimicrobial peptides (AMPs) has not been well described to date. Here, we utilized the structural advantages of HHC-10 and HHC-10 (Har, l-homoarginine) that are highly active Trp-rich AMPs and investigated their fibril formation and activity behavior against bacteria. The peptides revealed time-dependent self-assembly of polyproline II (PPII) α-helices, but by comparison, HHC-10 tended to form higher ordered fibrils due to relatively strong cation-π stacking of Trp with Har residue. Both peptides rapidly killed and at their MICs and caused aggregation of bacteria at higher concentrations. This bacterial aggregation was accompanied by the formation of morphologically distinct electron-dense nanostructures, likely including but not limited to peptides alone. Both HHC-10-derived peptides caused blebs and buds in the membrane that are rich in POPE phospholipid that promotes negative curvature. However, the main population of cells retained their cocci structure upon treatment with HHC peptides even at concentration higher than the MICs. In contrast, the cell aggregation was not induced by HHC fibrils that were most likely stabilized through intra-/intermolecular cation-π stacking. It is proposed that masking of these interactions might have resulted in diminished membrane association/insertion of the HHC nanostructures. The peptides caused aggregation of POPC/POPG (1/3) and POPE/POPG (3/1) liposomes. Nonetheless, disaggregation of the former vesicles was observed at ratios of lipid to peptide of greater than 6 and 24 for HHC-10 and HHC-10, respectively. Collectively, our results revealed dose-dependent bacterial aggregation mediated by Trp-rich AMPs that was profoundly influenced by the degree of peptide's self-association and the composition and intrinsic curvature of the cytoplasmic membrane lipids.
迄今为止，尚未很好地描述细胞质膜中侧链残基和磷脂特性对精氨酸（Arg）和色氨酸（Trp）丰富的抗菌肽（AMP）的纤维化和细菌聚集的影响。在这里，我们利用 HHC-10 和 HHC-10（Har，l-高精氨酸）的结构优势，它们是高度活跃的 Trp 丰富的 AMP，并研究了它们的纤维形成和针对细菌的活性行为。这些肽显示出聚脯氨酸 II（PPII）α-螺旋的时间依赖性自组装，但相比之下，由于 Har 残基与 Trp 之间相对较强的阳离子-π 堆积，HHC-10 往往会形成更高阶的纤维。两种肽都以其 MIC 迅速杀死 和 ，并在更高浓度下引起细菌聚集。这种细菌聚集伴随着形态独特的电子致密纳米结构的形成，可能包括但不限于单独的肽。两种 HHC-10 衍生肽都导致富含促进负曲率的 POPE 磷脂的 膜出现泡和芽。然而，在用 HHC 肽处理时，即使在高于 MIC 的浓度下， 细胞的主要群体仍保留其球菌结构。相比之下，HHC 纤维未诱导细胞聚集，这很可能是通过分子内/分子间阳离子-π 堆积稳定的。据推测，这些相互作用的掩盖可能导致 HHC 纳米结构与膜的结合/插入减少。肽引起 POPC/POPG（1/3）和 POPE/POPG（3/1）脂质体的聚集。尽管如此，在 HHC-10 和 HHC-10 分别为 6 和 24 以上的脂质与肽比的情况下，观察到前者囊泡的解聚集。总的来说，我们的结果显示了 Trp 丰富的 AMP 介导的剂量依赖性细菌聚集，该聚集受肽自组装程度以及细胞质膜脂质的组成和固有曲率的深刻影响。
