Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Saulėtekio Av. 3, LT-10257 Vilnius, Lithuania; Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10257 Vilnius, Lithuania.
Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Saulėtekio Av. 3, LT-10257 Vilnius, Lithuania; Institute of Chemical Physics, Faculty of Physics, Vilnius University, Saulėtekio Av. 9-III, LT-10222 Vilnius, Lithuania.
J Photochem Photobiol B. 2021 May;218:112174. doi: 10.1016/j.jphotobiol.2021.112174. Epub 2021 Mar 25.
Incorporation of membrane proteins into reconstituted lipid membranes is a common approach for studying their structure and function relationship in a native-like environment. In this work, we investigated fluorescence properties of liposome-reconstituted major light-harvesting complexes of plants (LHCII). By utilizing liposome labelling with the fluorescent dye molecules and single-molecule microscopy techniques, we were able to study truly liposome-reconstituted LHCII and compare them with bulk measurements and liposome-free LHCII aggregates bound to the surface. Our results showed that fluorescence lifetime obtained in bulk and in single liposome measurements were correlated. The fluorescence lifetimes of LHCII were shorter for liposome-free LHCII than for reconstituted LHCII. In the case of liposome-reconstituted LHCII, fluorescence lifetime showed dependence on the protein density reminiscent to concentration quenching. The dependence of fluorescence lifetime of LHCII on the liposome size was not significant. Our results demonstrated that fluorescence quenching can be induced by LHCII - LHCII interactions in reconstituted membranes, most likely occurring via the same mechanism as photoprotective non-photochemical quenching in vivo.
将膜蛋白掺入重建的脂质膜中是研究其在类似天然环境下的结构和功能关系的常用方法。在这项工作中，我们研究了植物主要光捕获复合物（LHCII）重建脂质体的荧光性质。通过利用荧光染料分子标记脂质体和单分子显微镜技术，我们能够研究真正的脂质体重建 LHCII，并将其与体相测量和结合在表面的无脂质体 LHCII 聚集体进行比较。我们的结果表明，在体相和单个脂质体测量中获得的荧光寿命是相关的。无脂质体 LHCII 的荧光寿命比重建的 LHCII 短。在重建的 LHCII 的情况下，荧光寿命表现出对蛋白密度的依赖性，类似于浓度猝灭。LHCII 的荧光寿命与脂质体大小的依赖性不显著。我们的结果表明，荧光猝灭可以在重建的膜中由 LHCII-LHCII 相互作用诱导，很可能通过与体内光保护非光化学猝灭相同的机制发生。
