Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan.
Nat Commun. 2022 Sep 9;13(1):5270. doi: 10.1038/s41467-022-32793-0.
Ion-transport mechanisms evolve by changing ion-selectivity, such as switching from Na to H selectivity in secondary-active transporters or P-type-ATPases. Here we study primary-active transport via P-type ATPases using functional and structural analyses to demonstrate that four simultaneous residue substitutions transform the non-gastric H/K pump, a strict H-dependent electroneutral P-type ATPase, into a bona fide Na-dependent electrogenic Na/K pump. Conversion of a H-dependent primary-active transporter into a Na-dependent one provides a prototype for similar studies of ion-transport proteins. Moreover, we solve the structures of the wild-type non-gastric H/K pump, a suitable drug target to treat cystic fibrosis, and of its Na/K pump-mimicking mutant in two major conformations, providing insight on how Na binding drives a concerted mechanism leading to Na/K pump phosphorylation.
离子转运机制通过改变离子选择性而进化，例如在次级主动转运体或 P 型-ATP 酶中将钠选择性转变为氢选择性。在这里，我们通过功能和结构分析研究了通过 P 型 ATP 酶的主动转运，以证明四个同时的残基取代将非胃 H/K 泵（一种严格依赖 H 的电中性 P 型 ATP 酶）转变为真正的 Na 依赖性电活性 Na/K 泵。将依赖 H 的主动转运体转化为依赖 Na 的转运体为离子转运蛋白的类似研究提供了原型。此外，我们解决了非胃 H/K 泵的野生型结构及其 Na/K 泵模拟突变体的两种主要构象，为 Na 结合如何驱动协同机制导致 Na/K 泵磷酸化提供了深入了解。
