Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, UPR 9080, Centre National de la Recherche Scientifique, Paris, France.
Institut de Biologie Physico-Chimique, Laboratoire de Biologie Cellulaire et Moléculaire des Eucaryotes, UMR 8226, Centre National de la Recherche Scientifique, Sorbonne Universités, UPMC University of Paris 06, Paris, France.
Sci Rep. 2017 Aug 31;7(1):10217. doi: 10.1038/s41598-017-10687-2.
Mitofusins are large transmembrane GTPases of the dynamin-related protein family, and are required for the tethering and fusion of mitochondrial outer membranes. Their full-length structures remain unknown, which is a limiting factor in the study of outer membrane fusion. We investigated the structure and dynamics of the yeast mitofusin Fzo1 through a hybrid computational and experimental approach, combining molecular modelling and all-atom molecular dynamics simulations in a lipid bilayer with site-directed mutagenesis and in vivo functional assays. The predicted architecture of Fzo1 improves upon the current domain annotation, with a precise description of the helical spans linked by flexible hinges, which are likely of functional significance. In vivo site-directed mutagenesis validates salient aspects of this model, notably, the long-distance contacts and residues participating in hinges. GDP is predicted to interact with Fzo1 through the G1 and G4 motifs of the GTPase domain. The model reveals structural determinants critical for protein function, including regions that may be involved in GTPase domain-dependent rearrangements.
线粒体融合蛋白是动力蛋白相关蛋白家族中的大型跨膜 GTPase，对于线粒体外膜的连接和融合是必需的。它们的全长结构仍然未知，这是外膜融合研究的一个限制因素。我们通过一种混合计算和实验方法研究了酵母线粒体融合蛋白 Fzo1 的结构和动力学，该方法结合了分子建模和在脂质双层中的全原子分子动力学模拟，以及定点突变和体内功能测定。Fzo1 的预测结构改进了当前的结构域注释，更精确地描述了由柔性铰链连接的螺旋跨度，这些铰链很可能具有功能意义。体内定点突变验证了该模型的重要方面，特别是长距离接触和参与铰链的残基。预测 GDP 通过 GTP 酶结构域的 G1 和 G4 基序与 Fzo1 相互作用。该模型揭示了对蛋白质功能至关重要的结构决定因素，包括可能参与 GTP 酶结构域依赖性重排的区域。
