Mechanical Properties of Nanoscopic Lipid Domains
Mechanical Properties of Nanoscopic Lipid Domains
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DOI：
10.1021/jacs.5b08894
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发表时间：
2015-12-23
影响因子：
15
通讯作者：
Katsaras, John
中科院分区：
文献类型：
--
作者：
Nickels, Jonathan D.;Cheng, Xiaolin;Katsaras, John
脂筏假说对细胞膜如何组织蛋白质和脂类以完成其许多重要功能提出了见解。然而，对于导致脂筏的形成、稳定性和大小的物理机制，基本的问题仍然存在。因此，人们对包含相似横向非均质性或区域的系统的研究产生了极大的兴趣。在目前的工作中，我们提出了一种实验方法，能够分离脂类结构域的弯曲模数。这是利用中子散射及其对氢的同位素的独特敏感性来实现的。结合对比度匹配方法和非弹性中子散射，我们分离出位于60 nm单层囊泡中的直径类似13 nm的结构域的弯曲模数，其脂质成分模拟哺乳动物的质膜外叶。重要的是，纳米域的弯曲模数不同于其周围连续相的模数。通过额外的结构测量和全原子模拟，我们还确定了纳米结构域在整个双层小叶中的注册。综上所述，这些结果提供了一些结构域/RAFT形成的理论模型，并强调了这样一个事实，即在解释脂质系统和生物膜中出现横向异质性时，必须考虑弯曲模数的失配。
The lipid raft hypothesis presents insights into how the cell membrane organizes proteins and lipids to accomplish its many vital functions. Yet basic questions remain about the physical mechanisms that lead to the formation, stability, and size of lipid rafts. As a result, much interest has been generated in the study of systems that contain similar lateral heterogeneities, or domains. In the current work we present an experimental approach that is capable of isolating the bending moduli of lipid domains. This is accomplished using neutron scattering and its unique sensitivity to the isotopes of hydrogen. Combining contrast matching approaches with inelastic neutron scattering, we isolate the bending modulus of similar to 13 nm diameter domains residing in 60 nm unilamellar vesicles, whose lipid composition mimics the mammalian plasma membrane outer leaflet. Importantly, the bending modulus of the nanoscopic domains differs from the modulus of the continuous phase surrounding them. From additional structural measurements and all-atom simulations, we also determine that nanoscopic domains are in-register across the bilayer leaflets. Taken together, these results inform a number of theoretical models of domain/raft formation and highlight the fact that mismatches in bending modulus must be accounted for when explaining the emergence of lateral heterogeneities in lipid systems and biological membranes.