From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia,
From the Research School of Biology, Australian National University, Canberra, ACT 2601, Australia.
J Biol Chem. 2019 Apr 5;294(14):5720-5734. doi: 10.1074/jbc.RA118.006706. Epub 2019 Feb 5.
The ATPase ATP4 is the target of a diverse range of antimalarial compounds, including the clinical drug candidate cipargamin. ATP4 was originally annotated as a Ca transporter, but recent evidence suggests that it is a Na efflux pump, extruding Na in exchange for H Here we demonstrate that ATP4 proteins belong to a clade of P-type ATPases that are restricted to apicomplexans and their closest relatives. We employed a variety of genetic and physiological approaches to investigate the ATP4 protein of the apicomplexan , ATP4. We show that ATP4 is a plasma membrane protein. Knockdown of ATP4 had no effect on resting pH or Ca but rendered parasites unable to regulate their cytosolic Na concentration ([Na]). ATP4 inhibitors caused an increase in [Na] and a cytosolic alkalinization in WT but not ATP4 knockdown parasites. Parasites in which ATP4 was knocked down or disrupted exhibited a growth defect, attributable to reduced viability of extracellular parasites. Parasites in which ATP4 had been disrupted showed reduced virulence in mice. These results provide evidence for ATP4 proteins playing a key conserved role in Na regulation in apicomplexan parasites.
ATP4 是多种抗疟化合物的作用靶点，包括临床候选药物西泊加明。ATP4 最初被注释为钙转运体，但最近的证据表明它是一种 Na 外排泵，通过排出 Na 来交换 H。在这里，我们证明 ATP4 蛋白属于 P 型 ATP 酶的一个分支，该分支仅限于顶复门生物及其最亲近的亲属。我们采用了多种遗传和生理方法来研究顶复门生物的 ATP4 蛋白。我们发现 ATP4 是一种质膜蛋白。敲低 ATP4 对静息 pH 或 Ca 没有影响，但使寄生虫无法调节其细胞内 Na 浓度([Na])。ATP4 抑制剂在 WT 但不是 ATP4 敲低寄生虫中引起 [Na]增加和细胞内碱化。敲低或破坏 ATP4 的寄生虫表现出生长缺陷，这归因于细胞外寄生虫的生存能力降低。破坏 ATP4 的寄生虫在小鼠中的毒力降低。这些结果为 ATP4 蛋白在顶复门寄生虫的 Na 调节中发挥关键保守作用提供了证据。
