Gehman John D, Luc Fiona, Hall Kristopher, Lee Tzong-Hsien, Boland Martin P, Pukala Tara L, Bowie John H, Aguilar Marie-Isabel, Separovic Frances
School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia.
Biochemistry. 2008 Aug 19;47(33):8557-65. doi: 10.1021/bi800320v. Epub 2008 Jul 25.
Skin secretions of numerous Australian tree frogs contain antimicrobial peptides that form part of the host defense mechanism against bacterial infection. The mode of action of these antibiotics is thought to be lysis of infectious organisms via cell membrane disruption, on the basis of vesicle-encapsulated dye leakage data [Ambroggio et al. (2005) Biophys. J. 89, 1874-1881]. A detailed understanding of the interaction of these peptides with bacterial membranes at a molecular level, however, is critical to their development as novel antibacterial therapeutics. We focus on four of these peptides, aurein 1.2, citropin 1.1, maculatin 1.1, and caerin 1.1, which exist as random coil in aqueous solution but have alpha-helical secondary structure in membrane mimetic environments. In our earlier solid-state NMR studies, only neutral bilayers of the zwitterionic phospholipid dimyristoylphosphatidylcholine (DMPC) were used. Deuterated DMPC ( d 54-DMPC) was used to probe the effect of the peptides on the order of the lipid acyl chains and dynamics of the phospholipid headgroups by deuterium and (31)P NMR, respectively. In this report we demonstrate several important differences when anionic phospholipid is included in model membranes. Peptide-membrane interactions were characterized using surface plasmon resonance (SPR) spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy. Changes in phospholipid motions and membrane binding information provided additional insight into the action of these antimicrobial peptides. While this set of peptides has significant C- and N-terminal sequence homology, they vary in their mode of membrane interaction. The longer peptides caerin and maculatin exhibited properties that were consistent with transmembrane insertion while citropin and aurein demonstrated membrane disruptive mechanisms. Moreover, aurein was unique with greater perturbation of neutral versus anionic membranes. The results are consistent with a surface interaction for aurein 1.2 and pore formation rather than membrane lysis by the longer peptides.
许多澳大利亚树蛙的皮肤分泌物含有抗菌肽，这些抗菌肽是宿主抵御细菌感染防御机制的一部分。基于囊泡包裹染料泄漏数据[安布罗吉奥等人（2005年）《生物物理杂志》89卷，1874 - 1881页]，这些抗生素的作用方式被认为是通过破坏细胞膜来裂解感染性生物体。然而，在分子水平上详细了解这些肽与细菌膜的相互作用，对于将它们开发为新型抗菌治疗药物至关重要。我们聚焦于其中四种肽，即奥瑞因1.2、柠檬素1.1、黄斑蛙素1.1和凯林1.1，它们在水溶液中以无规卷曲形式存在，但在模拟膜环境中具有α - 螺旋二级结构。在我们早期的固态核磁共振研究中，仅使用了两性离子磷脂二肉豆蔻酰磷脂酰胆碱（DMPC）的中性双层膜。分别使用氘代DMPC（d54 - DMPC）通过氘核磁共振和磷 - 31核磁共振来探究肽对脂质酰链有序性和磷脂头部基团动力学的影响。在本报告中，我们展示了在模型膜中包含阴离子磷脂时的几个重要差异。使用表面等离子体共振（SPR）光谱和固态核磁共振（NMR）光谱对肽 - 膜相互作用进行了表征。磷脂运动和膜结合信息的变化为这些抗菌肽的作用提供了额外的见解。虽然这组肽在C端和N端序列上有显著的同源性，但它们的膜相互作用模式各不相同。较长的肽凯林和黄斑蛙素表现出与跨膜插入一致的特性，而柠檬素和奥瑞因则展示出膜破坏机制。此外，奥瑞因独特之处在于对中性膜与阴离子膜的扰动更大。结果与奥瑞因1.2的表面相互作用以及较长肽形成孔道而非膜裂解一致。
