Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, South Kensington, London, SW7 2AZ, UK.
Max-Planck-Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931, Cologne, Germany.
Nat Commun. 2019 Mar 8;10(1):1130. doi: 10.1038/s41467-019-09089-x.
Conserved lipid transfer proteins of the Ups/PRELI family regulate lipid accumulation in mitochondria by shuttling phospholipids in a lipid-specific manner across the intermembrane space. Here, we combine structural analysis, unbiased genetic approaches in yeast and molecular dynamics simulations to unravel determinants of lipid specificity within the conserved Ups/PRELI family. We present structures of human PRELID1-TRIAP1 and PRELID3b-TRIAP1 complexes, which exert lipid transfer activity for phosphatidic acid and phosphatidylserine, respectively. Reverse yeast genetic screens identify critical amino acid exchanges that broaden and swap their lipid specificities. We find that amino acids involved in head group recognition and the hydrophobicity of flexible loops regulate lipid entry into the binding cavity. Molecular dynamics simulations reveal different membrane orientations of PRELID1 and PRELID3b during the stepwise release of lipids. Our experiments thus define the structural determinants of lipid specificity and the dynamics of lipid interactions by Ups/PRELI proteins.
Ups/PRELI 家族的保守脂质转移蛋白通过以脂质特异性的方式在跨膜间隙中穿梭磷脂，从而调节线粒体中的脂质积累。在这里，我们结合结构分析、酵母中的无偏遗传方法和分子动力学模拟，揭示了保守的 Ups/PRELI 家族中脂质特异性的决定因素。我们展示了人 PRELID1-TRIAP1 和 PRELID3b-TRIAP1 复合物的结构，它们分别对磷脂酸和磷脂酰丝氨酸具有脂质转移活性。反向酵母遗传筛选确定了关键性氨基酸交换，从而拓宽并交换了它们的脂质特异性。我们发现，参与头部基团识别和柔性环疏水性的氨基酸调节脂质进入结合腔。分子动力学模拟揭示了 PRELID1 和 PRELID3b 在逐步释放脂质过程中的不同膜取向。因此，我们的实验定义了 Ups/PRELI 蛋白的脂质特异性和脂质相互作用动力学的结构决定因素。
