Chemomechanical Coupling in Single-Molecule F-Type ATP Synthase

详细信息

下载全文

推荐本文 |

• 作者：Ryota Iino ; Yannick Rondelez ; Masasuke Yoshida and Hiroyuki Noji
• 关键词：F0F1 ; ATP synthase ; F1 ; ATPase ; rotary molecular motor ; single ; molecule imaging ; single ; molecule manipulation ; magnetic tweezers ; chemomechanical coupling ; microfabrication ; polydimethylsiloxane ; fluorescence resonance energy transfer
• 刊名：Journal of Bioenergetics and Biomembranes
• 出版时间：December 2005
• 出版年：2005
• 期刊代码：13_0145479X
• 类别：en
• 卷：37
• 期：6
• 页码：451-454
• 数据来源：sp

摘要

An extremely small reaction chamber with a volume of a few femtoliters was developed for a highly sensitive detection of biological reaction. By encapsulating a single F₁-ATPase (F₁) molecule with ADP and an inorganic phosphate in the chamber, the chemomechanical coupling efficiency of ATP synthesis catalyzed by reversely rotated F₁ was successfully determined (Rondelez et al., 2005a, Nature, 444, 773–777). While the α < eqid1 > β < eqid2 > γ subcomplex of F₁ generated ATP with a low efficiency (∼10%), inclusion of the ε subunit into the subcomplex enhanced the efficiency up to 77%. This raises a new question about the mechanism of F₀F₁-ATP synthase (F₀F₁): How does the ε subunit support the highly coupled ATP synthesis of F₁? To address this question, we measured the conformational dynamics of the ε subunit using fluorescence resonance energy transfer (FRET) at the single-molecule level. The experimental data revealed ε changes the conformation of its C-terminus helices in a nucleotide-dependent manner. It is plausible that the conformational change of ε switches the catalytic mode of F₀F₁ for highly coupled ATP synthesis.