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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• 作者：Yuji Furutani ; Takeshi Murata ; Hideki Kandori
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：March 9, 2011
• 年：2011
• 卷：133
• 期：9
• 页码：2860-2863
• 全文大小：759K
• 年卷期：v.133,no.9(March 9, 2011)
• ISSN：1520-5126

文摘

V-ATPase from Enterococcus hirae forms a large supramolecular protein complex (total molecular weight 700鈥?00) 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.