Zweytick Dagmar, Japelj Bostjan, Mileykovskaya Eugenia, Zorko Mateja, Dowhan William, Blondelle Sylvie E, Riedl Sabrina, Jerala Roman, Lohner Karl
Institute of Molecular Biosciences, Biophysics Division, University of Graz, Graz, Austria.
Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia.
PLoS One. 2014 Mar 3;9(3):e90228. doi: 10.1371/journal.pone.0090228. eCollection 2014.
Two types of recently described antibacterial peptides derived from human lactoferricin, either nonacylated or N-acylated, were studied for their different interaction with membranes of Escherichia coli in vivo and in model systems. Electron microscopy revealed striking effects on the bacterial membrane as both peptide types induced formation of large membrane blebs. Electron and fluorescence microscopy, however demonstrated that only the N-acylated peptides partially induced the generation of oversized cells, which might reflect defects in cell-division. Further a different distribution of cardiolipin domains on the E. coli membrane was shown only in the presence of the N-acylated peptides. The lipid was distributed over the whole bacterial cell surface, whereas cardiolipin in untreated and nonacylated peptide-treated cells was mainly located at the septum and poles. Studies with bacterial membrane mimics, such as cardiolipin or phosphatidylethanolamine revealed that both types of peptides interacted with the negatively charged lipid cardiolipin. The nonacylated peptides however induced segregation of cardiolipin into peptide-enriched and peptide-poor lipid domains, while the N-acylated peptides promoted formation of many small heterogeneous domains. Only N-acylated peptides caused additional severe effects on the main phase transition of liposomes composed of pure phosphatidylethanolamine, while both peptide types inhibited the lamellar to hexagonal phase transition. Lipid mixtures of phosphatidylethanolamine and cardiolipin revealed anionic clustering by all peptide types. However additional strong perturbation of the neutral lipids was only seen with the N-acylated peptides. Nuclear magnetic resonance demonstrated different conformational arrangement of the N-acylated peptide in anionic and zwitterionic micelles revealing possible mechanistic differences in their action on different membrane lipids. We hypothesized that both peptides kill bacteria by interacting with bacterial membrane lipids but only N-acylated peptides interact with both charged cardiolipin and zwitterionic phosphatidylethanolamine resulting in remodeling of the natural phospholipid domains in the E. coli membrane that leads to defects in cell division.
对最近描述的两种源自人乳铁蛋白的抗菌肽进行了研究，这两种抗菌肽一种是非酰化的，另一种是N - 酰化的，研究了它们在体内和模型系统中与大肠杆菌膜的不同相互作用。电子显微镜显示，这两种肽对细菌膜都有显著影响，因为它们都会诱导大的膜泡形成。然而，电子显微镜和荧光显微镜表明，只有N - 酰化肽会部分诱导超大细胞的产生，这可能反映了细胞分裂中的缺陷。此外，仅在存在N - 酰化肽的情况下，才显示出大肠杆菌膜上心磷脂结构域的不同分布。脂质分布在整个细菌细胞表面，而未处理和非酰化肽处理细胞中的心磷脂主要位于隔膜和两极。使用细菌膜模拟物（如心磷脂或磷脂酰乙醇胺）进行的研究表明，这两种肽都与带负电荷的心磷脂相互作用。然而，非酰化肽会诱导心磷脂分离成富含肽和贫肽的脂质结构域，而N - 酰化肽则促进形成许多小的异质结构域。只有N - 酰化肽对由纯磷脂酰乙醇胺组成的脂质体的主要相变产生额外的严重影响，而两种肽都抑制层状到六方相的转变。磷脂酰乙醇胺和心磷脂的脂质混合物显示所有肽类型都会引起阴离子聚集。然而，只有N - 酰化肽对中性脂质有额外的强烈扰动。核磁共振表明，N - 酰化肽在阴离子和两性离子胶束中的构象排列不同，揭示了它们对不同膜脂质作用的可能机制差异。我们推测，这两种肽都通过与细菌膜脂质相互作用来杀死细菌，但只有N - 酰化肽与带电荷的心磷脂和两性离子磷脂酰乙醇胺都相互作用，导致大肠杆菌膜中天然磷脂结构域的重塑，从而导致细胞分裂缺陷。
