Sodium or Lithium Ion-Binding-Induced Structural Changes in the K-Ring of V-ATPase from Enterococcus hirae Revealed by ATR-FTIR Spectroscopy
Sodium or Lithium Ion-Binding-Induced Structural Changes in the K-Ring of V-ATPase from Enterococcus hirae Revealed by ATR-FTIR Spectroscopy
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DOI：
10.1021/ja1116414
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发表时间：
2011-03-09
影响因子：
15
通讯作者：
Kandori, Hideki
中科院分区：
文献类型：
--
作者：
Furutani, Yuji;Murata, Takeshi;Kandori, Hideki
来自肠球菌的V-ATP酶形成一个大的超分子蛋白复合物（总分子量约为700000），并在生理上将Na（+）和Li（+）转运穿过疏水的脂质双层。这些阳离子在结合位点的稳定性已被讨论的基础上的X-射线晶体结构的膜嵌入域，K-环（Na（+）-和Li（+）-结合的形式）。在这里，钠或锂离子结合诱导的完整的V-ATP酶的差异红外光谱已首次在生理温度下，在足够量的水化。结果表明，钠或锂离子结合诱导Glu 139的去质子化，酪氨酸残基中的氢键变化，以及K环中的小构象变化。这些结构的变化，特别是去质子化的Glu 139，被认为是重要的减少能量障碍的阳离子通过膜的运输。
V-ATPase from Enterococcus hirae forms a large supramolecular protein complex (total molecular weight similar to 700 000) and physiologically transports Na(+) and Li(+) across a hydrophobic lipid bilayer. Stabilization of these cations in the binding site has been discussed on the basis of X-ray crystal structures of a membrane-embedded domain, the K-ring (Na(+)- and Li(+)-bound forms). Here, sodium or lithium ion-binding-induced difference IR spectra of the intact V-ATPase have for the first time been measured at physiological temperature under a sufficient amount of hydration. The results suggest that sodium or lithium ion binding induces the deprotonation of Glu139, a hydrogen-bonding change in the tyrosine residue, and a small conformational change in the K-ring. These structural changes, especially the deprotonation of Glu139, are considered to be important for reducing energetic barriers to the transport of cations through the membrane.