Recent advances in single-molecule spectroscopy studies on light-harvesting processes in oxygenic photosynthesis
Recent advances in single-molecule spectroscopy studies on light-harvesting processes in oxygenic photosynthesis
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DOI：
10.2142/biophysico.bppb-v19.0013
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发表时间：
2022-04-08
影响因子：
1.5
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中科院分区：
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光合作用捕光复合体(LHC)在集中来自太阳的光子能量方面发挥着关键作用，否则，这种能量只会在一秒钟内激发几次典型的色素分子，如叶绿素-a。络合物中紧密堆积的颜料确保了能量有效地传递到反应中心。同时，LHC具有转换到能量猝灭状态的能力，从而在过度光照条件下发挥光保护作用。光保护对产氧的光合作用生物尤其重要，因为在好氧条件下，有毒的活性氧物种可以通过光化学产生。由于各种类型的色素分子之间以及与周围蛋白质基质之间强烈相互作用的体系极其复杂，长期以来，人们一直难以理解在捕光和猝灭状态之间灵活切换的分子机制。单分子光谱学研究适合于揭示在普通系综测量中被遮盖的荧光性质所反映的LHC的构象动力学。最近先进的单分子光谱学研究揭示了LHC的荧光峰位、强度和寿命的动态涨落。观察到的动力学似乎与光保护能猝灭的柔性激活所需的构象可塑性有关。本文综述了近几年来氧合光合作用捕光系统的单分子光谱学研究进展。
Photosynthetic light-harvesting complexes (LHCs) play a crucial role in concentrating the photon energy from the sun that otherwise excites a typical pigment molecule, such as chlorophyll-a, only several times a second. Densely packed pigments in the complexes ensure efficient energy transfer to the reaction center. At the same time, LHCs have the ability to switch to an energy-quenching state and thus play a photoprotective role under excessive light conditions. Photoprotection is especially important for oxygenic photosynthetic organisms because toxic reactive oxygen species can be generated through photochemistry under aerobic conditions. Because of the extreme complexity of the systems in which various types of pigment molecules strongly interact with each other and with the surrounding protein matrixes, there has been long-standing difficulty in understanding the molecular mechanisms underlying the flexible switching between the light-harvesting and quenching states. Single-molecule spectroscopy studies are suitable to reveal the conformational dynamics of LHCs reflected in the fluorescence properties that are obscured in ordinary ensemble measurements. Recent advanced single-molecule spectroscopy studies have revealed the dynamical fluctuations of LHCs in their fluorescence peak position, intensity, and lifetime. The observed dynamics seem relevant to the conformational plasticity required for the flexible activations of photoprotective energy quenching. In this review, we survey recent advances in the single-molecule spectroscopy study of the light-harvesting systems of oxygenic photosynthesis.