Inter-subunit interaction of gastric H+,K+-ATPase prevents reverse reaction of the transport cycle
Inter-subunit interaction of gastric H+,K+-ATPase prevents reverse reaction of the transport cycle
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DOI：
10.1038/emboj.2009.102
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发表时间：
2009-06-03
期刊：
影响因子：
11.4
通讯作者：
Fujiyoshi, Yoshinori
中科院分区：
文献类型：
--
作者：
Abe, Kazuhiro;Tani, Kazutoshi;Fujiyoshi, Yoshinori
胃H+，K+-ATP酶是ATP驱动的质子泵，负责产生跨胃膜的百万倍质子梯度。我们提出的结构胃H+，K+-ATP酶在6.5埃的分辨率确定的二维晶体的电子晶体学。该结构显示催化α-亚基和非催化β-亚基呈假E2 P构象。与Na+，K+-ATP酶不同，β亚基的N-末端尾与α亚基的磷酸化结构域直接接触。这种相互作用可以将磷酸化结构域保持在适当的位置，从而稳定酶的构象并防止运输循环的逆反应。事实上，β-亚基N-末端的截短允许逆反应发生。这些结果表明，β-亚基N-末端阻止了从E2 P到E1 P的逆反应，这可能与体内大H+梯度的产生有关。The EMBO Journal（2009）28，1637-1643. doi：10.1038/doj.2009.102; 2009年4月23日在线发布
The gastric H+,K+-ATPase is an ATP-driven proton pump responsible for generating a million-fold proton gradient across the gastric membrane. We present the structure of gastric H+,K+-ATPase at 6.5 angstrom resolution as determined by electron crystallography of two-dimensional crystals. The structure shows the catalytic alpha-subunit and the non-catalytic beta-subunit in a pseudo-E2P conformation. Different from Na+,K+-ATPase, the N-terminal tail of the beta-subunit is in direct contact with the phosphorylation domain of the alpha-subunit. This interaction may hold the phosphorylation domain in place, thus stabilizing the enzyme conformation and preventing the reverse reaction of the transport cycle. Indeed, truncation of the beta-subunit N-terminus allowed the reverse reaction to occur. These results suggest that the beta-subunit N-terminus prevents the reverse reaction from E2P to E1P, which is likely to be relevant for the generation of a large H+ gradient in vivo situation. The EMBO Journal (2009) 28, 1637-1643. doi:10.1038/emboj.2009.102; Published online 23 April 2009