A new solution structure of ATP synthase subunit c from thermophilic Bacillus PS3, suggesting a local conformational change for H+-translocation.
A new solution structure of ATP synthase subunit c from thermophilic Bacillus PS3, suggesting a local conformational change for H+-translocation.
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DOI：
10.1016/j.jmb.2006.01.011
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发表时间：
2006-04
影响因子：
5.6
通讯作者：
Takayuki Nakano;T. Ikegami;Toshiharu Suzuki;Masasuke Yoshida;H. Akutsu
中科院分区：
文献类型：
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作者：
Takayuki Nakano;T. Ikegami;Toshiharu Suzuki;Masasuke Yoshida;H. Akutsu
在FoF1-ATP合酶中，fof1亚基的低聚物环作为fof1质子马达的旋转质子通道。在大肠杆菌Foc （EFoc）单体溶液结构的基础上，提出了c端螺旋的旋转加上Asp61侧链在去质子化过程中的重定向来驱动整个c环的旋转。我们在有机溶剂混合物（氯仿/甲醇（3:1,v/v））中测定了嗜热芽孢杆菌PS3 （TFoc）的核磁共振结构。结果表明，不受pH的影响，TFoc必需的gl56的羧基向发夹外侧突出，这是与EFoc中两个取向不同的第三个取向。因此，仅根据EFoc的构象来推断c环旋转的机理是不合适的。不同发夹结构的出现表明，发夹结构在螺旋旋转和轴向位移方面存在多个能量极小值。多重能量最小值也可以为c环结构中的不同寡聚态提供基础。根据这些结果和最近报道的酒石酸伊杆菌Na+- atp酶c环的晶体结构，讨论了与H+-易位耦合的Fomotor旋转机制。
In FoF1-ATP synthase, an oligomer ring of Foc subunits acts as a rotary proton channel of the Fo-proton motor. On the basis of the solution structure of the Escherichia coli Foc (EFoc) monomer, the rotation of the C-terminal helix coupled with the reorientation of the essential Asp61 side-chain on deprotonation was proposed to drive rotation of the whole c-ring. We have determined the NMR structure of Foc from thermophilic Bacillus PS3, TFoc, in an organic solvent mixture (chloroform/methanol (3:1, v/v)). Our results showed that, independent of pH, the carboxyl group of the essential Glu56 of TFoc protrudes toward the outside of the hairpin, a third orientation that differs from either of the two orientations in EFoc. Therefore, it would be inappropriate to draw conclusions about the mechanism of c-ring rotation on the basis of the conformations observed only for EFoc. The appearance of different hairpin structures shows that there are multiple energy minima for the hairpin structure in terms of helix rotation and axial displacement. The multiple energy minima may also provide a base for the different oligomeric states in the c-ring structure. A rotation mechanism of the Fomotor coupled with H+-translocation is discussed on the basis of these results and the recently reported crystal structure of the c-ring from Ilyobacter tartaricus Na+-ATPase.