Schaefer K G, Pittman A E, Barrera F N, King G M
Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO 65211, USA.
Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
Methods. 2022 Jan;197:20-29. doi: 10.1016/j.ymeth.2020.10.014. Epub 2020 Oct 24.
A number of peptides are known to bind lipid bilayer membranes and cause these natural barriers to leak in an uncontrolled manner. Though membrane permeabilizing peptides play critical roles in cellular activity and may have promising future applications in the therapeutic arena, significant questions remain about their mechanisms of action. The atomic force microscope (AFM) is a single molecule imaging tool capable of addressing lipid bilayers in near-native fluid conditions. The apparatus complements traditional assays by providing local topographic maps of bilayer remodeling induced by membrane permeabilizing peptides. The information garnered from the AFM includes direct visualization and statistical analyses of distinct bilayer remodeling modes such as highly localized pore-like voids in the bilayer and dispersed thinned membrane regions. Colocalization of distinct remodeling modes can be studied. Here we examine recent work in the field and outline methods used to achieve precise AFM image data. Experimental challenges and common pitfalls are discussed as well as techniques for unbiased analysis including the Hessian blob detection algorithm, bootstrapping, and the Bayesian information criterion. When coupled with robust statistical analyses, high precision AFM data is poised to advance understanding of an important family of peptides that cause poration of membrane bilayers.
已知许多肽能结合脂质双分子层膜,并导致这些天然屏障以不受控制的方式泄漏。尽管膜通透肽在细胞活动中发挥着关键作用,并且在治疗领域可能有广阔的应用前景,但关于它们的作用机制仍存在重大问题。原子力显微镜(AFM)是一种单分子成像工具,能够在接近天然的流体条件下研究脂质双分子层。该仪器通过提供膜通透肽诱导的双分子层重塑的局部地形图来补充传统检测方法。从原子力显微镜获得的信息包括对不同双分子层重塑模式的直接可视化和统计分析,如双分子层中高度局部化的孔状空隙和分散的变薄膜区域。可以研究不同重塑模式的共定位。在这里,我们研究了该领域的最新工作,并概述了用于获取精确原子力显微镜图像数据的方法。讨论了实验挑战和常见陷阱,以及包括黑塞斑点检测算法、自举法和贝叶斯信息准则在内的无偏分析技术。当与强大的统计分析相结合时,高精度的原子力显微镜数据有望推动对导致膜双分子层形成孔道的重要肽家族的理解。