The membrane domain of the Na+-motive V-ATPase from Enterococcus hirae contains a heptameric rotor
The membrane domain of the Na+-motive V-ATPase from Enterococcus hirae contains a heptameric rotor
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DOI：
10.1074/jbc.m301620200
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发表时间：
2003-06-06
影响因子：
4.8
通讯作者：
Walker, JE
中科院分区：
文献类型：
--
作者：
Murata, T;Arechaga, I;Walker, JE
在F-ATP酶中，ATP水解通过膜中c亚基环的旋转与离子穿过膜的移位偶联。该环连接到穿透催化域的中心轴，其具有伪3重对称性。离子移位途径位于环的外周和另一个疏水蛋白之间。H+或Na+：ATP的比例取决于环原体的数量，每个环原体都有一个直接参与离子移位的必需羧酸根。这个数字和比率根据来源而不同，在各种酶中发现了10，11和14个原体，相应的计算H+或Na+：ATP比率为3.3，3.7和4.7。V-ATP酶在结构和功能上与F-ATP酶相关。来自肠球菌Na+动力V-ATP酶的K亚基的寡聚体也形成膜环，但如本文所报道的，具有7重对称性。每一个原体都有一个必需的羧酸根。因此，一个ATP的水解提供能量以挤出2.3个钠离子。催化结构域和膜结构域之间的对称性错配似乎是V-和F-ATP酶的固有特征。
In F-ATPases, ATP hydrolysis is coupled to translocation of ions through membranes by rotation of a ring of c subunits in the membrane. The ring is attached to a central shaft that penetrates the catalytic domain, which has pseudo-3-fold symmetry. The ion translocation pathway lies between the external circumference of the ring and another hydrophobic protein. The H+ or Na+: ATP ratio depends upon the number of ring protomers, each of which has an essential carboxylate involved directly in ion translocation. This number and the ratio differ according to the source, and 10, 11, and 14 protomers have been found in various enzymes, with corresponding calculated H+ or Na+: ATP ratios of 3.3, 3.7, and 4.7. V-ATPases are related in structure and function to F-ATPases. Oligomers of subunit K from the Na+-motive V-ATPase of Enterococcus hirae also form membrane rings but, as reported here, with 7-fold symmetry. Each protomer has one essential carboxylate. Thus, hydrolysis of one ATP provides energy to extrude 2.3 sodium ions. Symmetry mismatch between the catalytic and membrane domains appears to be an intrinsic feature of both V- and F-ATPases.