1Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Plaza de Ciencias, 1, 28040 Madrid, Spain.
2Departamento de Química Física, Universidad Complutense de Madrid, Avda. Complutense, s/n, 28040 Madrid, Spain.
Commun Biol. 2019 Jun 20;2:225. doi: 10.1038/s42003-019-0471-x. eCollection 2019.
Cardiolipin is a cone-shaped lipid predominantly localized in curved membrane sites of bacteria and in the mitochondrial cristae. This specific localization has been argued to be geometry-driven, since the CL's conical shape relaxes curvature frustration. Although previous evidence suggests a coupling between CL concentration and membrane shape in vivo, no precise experimental data are available for curvature-based CL sorting in vitro. Here, we test this hypothesis in experiments that isolate the effects of membrane curvature in lipid-bilayer nanotubes. CL sorting is observed with increasing tube curvature, reaching a maximum at optimal CL concentrations, a fact compatible with self-associative clustering. Observations are compatible with a model of membrane elasticity including van der Waals entropy, from which a negative intrinsic curvature of -1.1 nm is predicted for CL. The results contribute to understanding the physicochemical interplay between membrane curvature and composition, providing key insights into mitochondrial and bacterial membrane organization and dynamics.
心磷脂是一种锥形脂质，主要定位于细菌的弯曲膜位点和线粒体嵴中。这种特定的定位被认为是几何驱动的，因为 CL 的锥形形状缓解了曲率的挫败感。尽管先前的证据表明 CL 浓度与体内膜形状之间存在耦合，但目前还没有关于体外基于曲率的 CL 分类的精确实验数据。在这里，我们在分离脂质双层纳米管中膜曲率影响的实验中测试了这一假设。随着管曲率的增加，观察到 CL 分类，在最佳 CL 浓度下达到最大值，这一事实与自缔合聚类兼容。观察结果与包括范德华熵在内的膜弹性模型兼容，根据该模型，CL 的固有曲率预测为-1.1nm。该结果有助于理解膜曲率和组成之间的物理化学相互作用，为线粒体和细菌膜的组织和动力学提供了关键的见解。
