Dynamics of bacteriorhodopsin in solid-supported purple membranes studied with tapping-mode atomic force microscopy.
Dynamics of bacteriorhodopsin in solid-supported purple membranes studied with tapping-mode atomic force microscopy.
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用敲击模式原子力显微镜研究固相紫色膜中细菌视紫红质的动力学
DOI：
10.1021/jp102377c
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
N. Hampp
中科院分区：
文献类型：
--
作者：
M. Schranz;R.-P. Baumann;D. Rhinow;N. Hampp
盐生盐杆菌的紫膜（PM）是一种由细菌视紫红质（BR）和脂质组成的膜蛋白，已被许多研究小组用作研究膜蛋白结构和动力学的模型系统。虽然BR在PM内的构象动力学已被广泛分析与亚纳米分辨率的衍射实验和光谱方法的手段，以及，结构研究的动态转换在单个PM是罕见的。在这项工作中，我们表明，扫描模式原子力显微镜（TM-AFM）是非常适合于研究在纳米级的固体支持PM内的动态转变。时间依赖的AFM分析固体支持的PM显示，再分配过程之间发生的结晶核心区域，具有高度为1.5 nm，和高度移动的边缘区域（高度为1.4 nm）。讨论了温度和衬底对平衡的影响。实验的补充静电力显微镜（EFM）的PM云母。除了它们对许多生理过程的重要性之外，如在这项工作中观察到的，生物膜中的动态转变对于利用固体支撑膜组件的所有方法（无论是分析工具还是应用）都至关重要。
Purple membrane (PM) from Halobacterium salinarum, which comprises bacteriorhodopsin (BR) and lipids only, has been employed by many groups as a model system to study the structure and dynamics of membrane proteins. Although the conformational dynamics of BR within PM has been extensively analyzed with subnanometer resolution by means of diffraction experiments and spectroscopic methods, as well, structural studies of dynamical transitions within single PMs are rare. In this work, we show that tapping-mode atomic force microscopy (TM-AFM) is ideally suited to study dynamical transitions within solid-supported PMs at the nanoscale. Time-dependent AFM analysis of solid-supported PMs shows that redistribution processes take place between a crystalline core region, featuring a height of ∼5 nm, and a highly mobile rim region (∼4 nm in height). Furthermore, we discuss the influence of temperature and substrate on the equilibrium. The experiments are complemented by electrostatic force microscopy (EFM) of PM on mica. Beyond their importance for many physiological processes, dynamical transitions in biological membranes, as observed in this work, are of critical importance for all methods that make use of solid-supported membrane assemblies, either analytical tools or applications.