Quinones operate as proton-collecting antennas in energy-transducing membranes.
醌类化合物在能量转换膜中发挥质子收集天线的作用。
Adel Beghiah, Niusha Bagheri, Sofia Badolato, Hyunho Kim, Timir Sil, Maximilian Pöverlein, Jerker Widengren, Ville Kaila (2026) Quinones operate as proton-collecting antennas in energy-transducing membranes. Proc Natl Acad Sci U S A (IF: 9.1) 1 区 123(16) e2534025123
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Abstract
The bioenergetic complexes of energy-transducing membranes generate a proton current that powers the synthesis of adenosine triphosphate. Yet, since the early days of the chemiosmotic theory, it has remained elusive and much debated whether the proton motive force (PMF) delocalizes into the bulk solvent surrounding the energy-transducing membrane or if the thermodynamic force is exerted as a localized proton current along the membrane surface. To elucidate the molecular principles underlying protonation dynamics at biological membranes, we combine here proteoliposome experiments with fluorescence correlation spectroscopy and multiscale molecular simulations. We show that ubiquinone (Q10), which is an essential electron carrier of inner mitochondrial membranes, interacts with protons at the membrane, and alters the rate of the protonation reactions along the surface. We find that physiological Q10 concentrations increase the integrity of the liposome membranes to sustain a PMF and enhance the rate of surface protonation reactions of lipid-conjugated pH-sensitive fluorophores, occurring on a microsecond timescale. Our multiscale simulations reveal that the quinone headgroup localizes at the membrane surface and stabilizes protonated water species by cation-π and hydrogen-bonded interactions amplifying the proton exchange on the surface relative to the bulk solvent. We suggest that in addition to the well-established role of quinones as redox mediators in energy-transducing membranes, Q10 also promotes the proton-collecting antenna effect, mediating proton exchange along the membrane and supporting a local proton circuit model. Our combined findings provide molecular insight into propagation of proton currents along biological membranes and reveal key principles underlying the energy conversion mechanisms in biology.
能量转换膜的生物能量复合物产生质子流，为三磷酸腺苷（ATP）的合成提供能量。然而，自化学渗透理论诞生之初，质子动力势（PMF）究竟是离域到能量转换膜周围的溶剂中，还是以局域质子流的形式沿膜表面发挥作用，一直是一个难以捉摸且争论不休的问题。为了阐明生物膜质子化动力学的分子机制，我们结合了蛋白脂质体实验、荧光相关光谱和多尺度分子模拟。我们发现，作为线粒体内膜重要电子载体的泛醌（Q10）能够与膜上的质子相互作用，并改变膜表面的质子化反应速率。我们发现，生理浓度的辅酶Q10能够增强脂质体膜的完整性，从而维持质子动力势（PMF），并提高脂质偶联的pH敏感荧光团的表面质子化反应速率，该反应发生在微秒时间尺度上。我们的多尺度模拟表明，醌类头基定位于膜表面，并通过阳离子-π相互作用和氢键作用稳定质子化水分子，从而增强膜表面相对于本体溶剂的质子交换。我们认为，除了醌类作为能量转换膜中氧化还原介质的既定作用外，辅酶Q10还能促进质子收集天线效应，介导膜上的质子交换，并支持局部质子回路模型。我们的综合发现为质子电流沿生物膜的传播提供了分子层面的见解，并揭示了生物能量转换机制的关键原理。
Links
http://www.ncbi.nlm.nih.gov/pubmed/41980103http://dx.doi.org/10.1073/pnas.2534025123
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