The c-ring stoichiometry of ATP synthase is adapted to cell physiological requirements of alkaliphilic Bacillus pseudofirmus OF4
The c-ring stoichiometry of ATP synthase is adapted to cell physiological requirements of alkaliphilic Bacillus pseudofirmus OF4
复制标题
DOI：
10.1073/pnas.1303333110
复制
发表时间：
2013-05-07
影响因子：
11.1
通讯作者：
Meier, Thomas
中科院分区：
文献类型：
--
作者：
Preiss, Laura;Klyszejko, Adriana L.;Meier, Thomas
ATP酶的C环由单独的C亚基组成，所有这些C亚基都具有对于紧密跨膜α-螺旋包装重要的重复甘氨酸残基（GxGxGxG）的保守基序。C环化学计量决定了酶操作过程中转移的离子数量，并直接影响离子与ATP的比率，这是细胞生物能量学的基石参数。在极端嗜碱假坚强芽孢杆菌OF 4中，甘氨酸基序被AxAxAxA取代。我们使用原子力显微镜和X射线晶体学对两个丙氨酸变为甘氨酸的突变体进行了结构研究，发现突变体形成的c（12）环比WT c（13）环小。B的摩尔生长产率。pseudofirmus OF 4细胞在苹果酸上的生长进一步揭示了c（12）突变体在高pH下在限制苹果酸上生长的能力显著降低。我们的结果表明具有c（12）或c（13）的突变体ATP酶可以支持ATP合成，并且还强调了具有c（13）环化学计量的丙氨酸基序对于pH > 10的最佳生长的至关重要性。这些数据表明，精确适应的ATP合成酶的C-环化学计量和它的离子-ATP比对细胞生理学之间的直接联系，也证明了生物能源的挑战和极端微生物的进化适应策略。
The c-rings of ATP synthases consist of individual c-subunits, all of which harbor a conserved motif of repetitive glycine residues (GxGxGxG) important for tight transmembrane a-helix packing. The c-ring stoichiometry determines the number of ions transferred during enzyme operation and has a direct impact on the ion-to-ATP ratio, a cornerstone parameter of cell bioenergetics. In the extreme alkaliphile Bacillus pseudofirmus OF4, the glycine motif is replaced by AxAxAxA. We performed a structural study on two mutants with alanine-to-glycine changes using atomic force microscopy and X-ray crystallography, and found that mutants form smaller c(12) rings compared with the WT c(13). The molar growth yields of B. pseudofirmus OF4 cells on malate further revealed that the c(12) mutants have a considerably reduced capacity to grow on limiting malate at high pH. Our results demonstrate that the mutant ATP synthases with either c(12) or c(13) can support ATP synthesis, and also underscore the critical importance of an alanine motif with c(13) ring stoichiometry for optimal growth at pH > 10. The data indicate a direct connection between the precisely adapted ATP synthase c-ring stoichiometry and its ion-to-ATP ratio on cell physiology, and also demonstrate the bioenergetic challenges and evolutionary adaptation strategies of extremophiles.