Mahato Dhani Ram, Andersson Magnus
Department of Chemistry, Umeå University, Umeå, Sweden; Institut de Química Computacional i Catàlisi, Universitat de Girona, Girona, 17003, Spain.
Department of Chemistry, Umeå University, Umeå, Sweden.
Biochim Biophys Acta Mol Cell Res. 2023 Oct;1870(7):119545. doi: 10.1016/j.bbamcr.2023.119545. Epub 2023 Jul 20.
The function of ion-transporting Na,K-ATPases depends on the surrounding lipid environment in biological membranes. Two established lipid-interaction sites A and B within the transmembrane domain have been observed to induce protein activation and stabilization, respectively. In addition, lipid-mediated inhibition has been assigned to a site C, but with the exact location not experimentally confirmed. Also, possible effects on lipid interactions by disease mutants dwelling in the membrane-protein interface remain relatively uncharacterized. We simulated human Na,K-ATPase αβFXYD homology models in E1 and E2 states in an asymmetric, multicomponent plasma membrane to determine both wild-type and disease mutant lipid-protein interactions. The simulated wild-type lipid interactions at the established sites A and B were in agreement with experimental results thereby confirming the membrane-protein model system. The less well-characterized, proposed inhibitory site C was dominated by lipids lacking inhibitory properties. Instead, two sites hosting inhibitory lipids were identified at the extracellular side and also a cytoplasmic CHL-binding site that provide putative alternative locations of Na,K-ATPase inhibition. Three disease mutations, Leu302Arg, Glu840Arg and Met859Arg resided in the lipid-protein interface and caused drastic changes in the lipid interactions. The simulation results show that lipid interactions to the human Na,K-ATPase αβFXYD protein in the plasma membrane are highly state-dependent and can be disturbed by disease mutations located in the lipid interface, which can open up for new venues to understand genetic disorders.
离子转运钠钾ATP酶的功能取决于生物膜中周围的脂质环境。已观察到跨膜结构域内两个已确定的脂质相互作用位点A和B分别诱导蛋白质激活和稳定。此外，脂质介导的抑制作用已归因于位点C，但确切位置尚未通过实验证实。同样，位于膜 - 蛋白界面的疾病突变体对脂质相互作用的可能影响仍相对未被表征。我们在不对称的多组分质膜中模拟了处于E1和E2状态的人钠钾ATP酶αβFXYD同源模型，以确定野生型和疾病突变体的脂质 - 蛋白相互作用。在已确定的位点A和B处模拟的野生型脂质相互作用与实验结果一致，从而证实了膜 - 蛋白模型系统。表征较少的推测抑制位点C主要由缺乏抑制特性的脂质主导。相反，在细胞外侧鉴定出两个含有抑制性脂质的位点，以及一个细胞质CHL结合位点，它们提供了钠钾ATP酶抑制的假定替代位置。三个疾病突变Leu302Arg、Glu840Arg和Met859Arg位于脂质 - 蛋白界面，导致脂质相互作用发生剧烈变化。模拟结果表明，质膜中脂质与人钠钾ATP酶αβFXYD蛋白的相互作用高度依赖于状态，并且可能被位于脂质界面的疾病突变所干扰，这为理解遗传疾病开辟了新途径。
