State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
Cell Rep. 2022 Mar 15;38(11):110518. doi: 10.1016/j.celrep.2022.110518.
Type 4 P-type ATPases (P4-ATPases) actively and selectively translocate phospholipids across membrane bilayers. Driven by ATP hydrolysis, P4-ATPases undergo conformational changes during lipid flipping. It is unclear how the active flipping states of P4-ATPases are regulated in the lipid membranes, especially for phosphatidylcholine (PC)-flipping P4-ATPases whose substrate, PC, is a substantial component of membranes. Here, we report the cryoelectron microscopy structures of a yeast PC-flipping P4-ATPase, Dnf1, in lipid environments. In native yeast lipids, Dnf1 adopts a conformation in which the lipid flipping pathway is disrupted. Only when the lipid composition is changed can Dnf1 be captured in the active conformations that enable lipid flipping. These results suggest that, in the native membrane, Dnf1 may stay in an idle conformation that is unable to support the trans-membrane movement of lipids. Dnf1 may have altered conformational preferences in membranes with different lipid compositions.
4 型 P 型 ATP 酶（P4-ATPases）在跨膜双层中主动且选择性地转运磷脂。在 ATP 水解的驱动下，P4-ATPase 在脂质翻转过程中经历构象变化。目前尚不清楚 P4-ATPase 的活性翻转状态如何在脂质膜中受到调节，特别是对于磷脂酰胆碱（PC）翻转 P4-ATPase，其底物 PC 是膜的主要成分之一。在这里，我们报告了酵母 PC 翻转 P4-ATPase Dnf1 在脂质环境中的冷冻电镜结构。在天然酵母脂质中，Dnf1 采用了一种阻断脂质翻转途径的构象。只有当脂质组成发生变化时，Dnf1 才能被捕获到能够进行脂质翻转的活性构象中。这些结果表明，在天然膜中，Dnf1 可能处于一种无法支持脂质跨膜运动的空闲构象。Dnf1 在具有不同脂质组成的膜中可能具有改变的构象偏好。
