On the Mg2+ binding site of the ε subunit from bacterial F-type ATP synthases
On the Mg2+ binding site of the ε subunit from bacterial F-type ATP synthases
复制标题
细菌 F 型 ATP 合酶 ε 亚基的 Mg2+ 结合位点
DOI：
10.1016/j.bbabio.2015.05.018
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Alexander Krah and Shoji Takada
中科院分区：
文献类型：
--
作者：
Kazuhiro Ishishita;Noriyuki Suetusgu;Yuki Hirose;Takeshi Higa;Michio Doi;Masamitsu Wada;Tomonao Matsushita;Eiji Gotoh;Alexander Krah and Shoji Takada
F型三磷酸腺苷合成酶是细胞的中心能量转换机器，利用跨膜的电化学梯度合成三磷酸腺苷(ATP)，反过来，也可以根据细胞条件(如三磷酸腺苷浓度)水解三磷酸腺苷，将离子泵过膜。为了防止浪费的ATP水解，哺乳动物和细菌的ATP合成酶具有不同的调节机制。在细菌中，低浓度的三磷酸腺苷诱导ε亚基的构象从下降状态转变为上升状态，从而抑制三磷酸腺苷的水解。此外，在枯草芽孢杆菌等细菌中，ε亚基的构象变化依赖于镁离子浓度，而在另一些细菌中则不依赖于镁离子浓度。这种多样性使ε亚单位成为抗生素的潜在靶点。在这里，通过分子动力学模拟，我们确定了ε亚基中的镁离子结合部位。枯草杆菌E59和E86。自由能分析表明，两种谷氨酸对镁离子的第一球双齿配位是最稳定的状态。通过比较，我们还阐明了嗜热芽孢杆菌PS3的ε亚基中没有镁离子依赖性的原因，尽管与B的同源性很高。枯草杆菌。序列比对表明，这个镁结合基序存在于一些病原菌的ε亚基中。此外，我们还讨论了通过定点突变来稳定携带镁离子结合基序的分离的ε亚基的策略，这也可以用于未来结晶依赖镁离子的ε亚基。
F-type ATP synthases, central energy conversion machines of the cell synthesize adenosine triphosphate (ATP) using an electrochemical gradient across the membrane and, reversely, can also hydrolyze ATP to pump ions across the membrane, depending on cellular conditions such as ATP concentration. To prevent wasteful ATP hydrolysis, mammalian and bacterial ATP synthases possess different regulatory mechanisms. In bacteria, a low ATP concentration induces a conformational change in the ε subunit from the down- to up-states, which inhibits ATP hydrolysis. Moreover, the conformational change of the ε subunit depends on Mg2+concentration in some bacteria such asBacillus subtilis, but not in others. This diversity makes the ε subunit a potential target for antibiotics. Here, performing molecular dynamics simulations, we identify the Mg2+binding site in the ε subunit fromB. subtilisas E59 and E86. The free energy analysis shows that the first-sphere bi-dentate coordination of the Mg2+ion by the two glutamates is the most stable state. In comparison, we also clarify the reason for the absence of Mg2+dependency in the ε subunit from thermophilicBacillusPS3, despite the high homology to that fromB. subtilis. Sequence alignment suggests that this Mg2+binding motif is present in the ε subunits of some pathogenic bacteria. In addition we discuss strategies to stabilize an isolated ε subunit carrying the Mg2+binding motif by site directed mutagenesis, which also can be used to crystallize Mg2+dependent ε subunits in future.