Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden.
Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology (KTH), SE-106 91, Stockholm, Sweden.
Sci Rep. 2017 Jun 7;7(1):2926. doi: 10.1038/s41598-017-02836-4.
We have investigated the effect of lipid composition on interactions between cytochrome bo and ATP-synthase, and the ATP-synthesis activity driven by proton pumping. The two proteins were labeled by fluorescent probes and co-reconstituted in large (d ≅ 100 nm) or giant (d ≅ 10 µm) unilamellar lipid vesicles. Interactions were investigated using fluorescence correlation/cross-correlation spectroscopy and the activity was determined by measuring ATP production, driven by electron-proton transfer, as a function of time. We found that conditions that promoted direct interactions between the two proteins in the membrane (higher fraction DOPC lipids or labeling by hydrophobic molecules) correlated with an increased activity. These data indicate that the ATP-synthesis rate increases with decreasing distance between cytochrome bo and the ATP-synthase, and involves proton transfer along the membrane surface. The maximum distance for lateral proton transfer along the surface was found to be ~80 nm.
我们研究了脂质组成对细胞色素 bo 与 ATP 合酶相互作用以及质子泵驱动的 ATP 合成活性的影响。这两种蛋白质用荧光探针标记，并在大（d ≅ 100nm）或巨（d ≅ 10μm）单层脂质囊泡中重新组成。使用荧光相关/交叉相关光谱法研究了相互作用，并通过测量电子质子转移驱动的 ATP 产生随时间的变化来确定活性。我们发现，促进膜中两种蛋白质直接相互作用的条件（较高的 DOPC 脂质分数或疏水分子标记）与活性增加相关。这些数据表明，ATP 合成速率随细胞色素 bo 和 ATP 合酶之间的距离减小而增加，并涉及质子沿膜表面的转移。沿表面横向质子转移的最大距离约为 80nm。
