Masaike Tomoko, Suzuki Toshiharu, Tsunoda Satoshi P, Konno Hiroki, Yoshida Masasuke
ATP System Project, Exploratory Research for Advanced Technology, Japan Science and Technology Corporation (JST), 5800-3 Nagatsuta, Yokohama 226-0026, Japan.
Biochem Biophys Res Commun. 2006 Apr 14;342(3):800-7. doi: 10.1016/j.bbrc.2006.02.017. Epub 2006 Feb 17.
A subcomplex of F0F1-ATP synthase (F0F1), alpha3beta3gamma, was shown to undergo the conformation(s) during ATP hydrolysis in which two of the three beta subunits have the "Closed" conformation simultaneously (CC conformation) [S.P. Tsunoda, E. Muneyuki, T. Amano, M. Yoshida, H. Noji, Cross-linking of two beta subunits in the closed conformation in F1-ATPase, J. Biol. Chem. 274 (1999) 5701-5706]. This was examined by the inter-subunit disulfide cross-linking between two mutant beta(I386C)s that was formed readily only when the enzyme was in the CC conformation. Here, we adopted the same method for the holoenzyme F0F1 from Bacillus PS3 and found that the CC conformation was generated during ATP hydrolysis but barely during ATP synthesis. The experiments using F0F1 with the epsilon subunit lacking C-terminal helices further suggest that this difference is related to dynamic nature of the epsilon subunit and that ATP synthesis is accelerated when it takes the pathway involving the CC conformation.
F0F1 - ATP合酶（F0F1）的一个亚复合体α3β3γ，已被证明在ATP水解过程中会经历某种构象，其中三个β亚基中的两个会同时处于“封闭”构象（CC构象）[S.P. 津野田、E. 宗之、T. 天野、M. 吉田、H. 野路，F1 - ATP酶中处于封闭构象的两个β亚基的交联，《生物化学杂志》274 (1999) 5701 - 5706]。这是通过两个突变β（I386C）之间的亚基间二硫键交联来检测的，只有当酶处于CC构象时，这种交联才容易形成。在这里，我们对来自芽孢杆菌PS3的全酶F0F1采用了相同的方法，发现CC构象在ATP水解过程中产生，但在ATP合成过程中几乎不产生。使用缺乏C末端螺旋的ε亚基的F0F1进行的实验进一步表明，这种差异与ε亚基的动态性质有关，并且当它采用涉及CC构象的途径时，ATP合成会加速。
