Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
Nat Commun. 2020 Aug 6;11(1):3921. doi: 10.1038/s41467-020-17762-9.
The vacuolar-type H-ATPases (V-ATPase) hydrolyze ATP to pump protons across the plasma or intracellular membrane, secreting acids to the lumen or acidifying intracellular compartments. It has been implicated in tumor metastasis, renal tubular acidosis, and osteoporosis. Here, we report two cryo-EM structures of the intact V-ATPase from bovine brain with all the subunits including the subunit H, which is essential for ATPase activity. Two type-I transmembrane proteins, Ac45 and (pro)renin receptor, along with subunit c", constitute the core of the c-ring. Three different conformations of A/B heterodimers suggest a mechanism for ATP hydrolysis that triggers a rotation of subunits DF, inducing spinning of subunit d with respect to the entire c-ring. Moreover, many lipid molecules have been observed in the Vo domain to mediate the interactions between subunit c, c", (pro)renin receptor, and Ac45. These two structures reveal unique features of mammalian V-ATPase and suggest a mechanism of V1-Vo torque transmission.
液泡型 H+-ATP 酶（V-ATPase）通过水解 ATP 将质子从质膜或细胞内膜泵出，将酸分泌到腔室或酸化细胞内隔室。它与肿瘤转移、肾小管酸中毒和骨质疏松症有关。在这里，我们报告了来自牛脑的完整 V-ATPase 的两个冷冻电镜结构，其中包含对 ATP 酶活性至关重要的亚基 H。两种 I 型跨膜蛋白 Ac45 和（前）肾素受体以及亚基 c"，构成了 c 环的核心。A/B 异二聚体的三种不同构象表明了 ATP 水解的机制，该机制触发了亚基 DF 的旋转，从而引起亚基 d 相对于整个 c 环的旋转。此外，在 Vo 结构域中观察到许多脂质分子，以介导亚基 c、c"、（前）肾素受体和 Ac45 之间的相互作用。这两个结构揭示了哺乳动物 V-ATPase 的独特特征，并提出了 V1-Vo 扭矩传递的机制。
