Integral membrane proteins are exposed to a complex and dynamic lipid environment modulated by nonbilayer lipids that can influence protein functions by lipid-protein interactions. The nonbilayer lipid monogalactosyldiacylglycerol (MGDG) is the most abundant lipid in plant photosynthetic thylakoid membranes, but its impact on the functionality of energy-converting membrane protein complexes is unknown. Here, we optimized a detergent-based reconstitution protocol to develop a proteoliposome technique that incorporates the major light-harvesting complex II (LHCII) into compositionally well-defined large unilamellar lipid bilayer vesicles to study the impact of MGDG on light harvesting by LHCII. Using steady-state fluorescence spectroscopy, CD spectroscopy, and time-correlated single-photon counting, we found that both chlorophyll fluorescence quantum yields and fluorescence lifetimes clearly indicate that the presence of MGDG in lipid bilayers switches LHCII from a light-harvesting to a more energy-quenching mode that dissipates harvested light into heat. It is hypothesized that in the in vitro system developed here, MGDG controls light harvesting of LHCII by modulating the hydrostatic lateral membrane pressure profile in the lipid bilayer sensed by LHCII-bound peripheral pigments.

中文翻译：

---

基于蛋白脂质体的系统揭示了脂质如何控制光合光的收集。

整体膜蛋白暴露于非双层脂质调节的复杂动态脂质环境中，该环境可通过脂质-蛋白质相互作用影响蛋白质功能。非双层脂质单半乳糖基二酰基甘油（MGDG）是植物光合类囊体膜中最丰富的脂质，但其对能量转换膜蛋白复合物功能的影响尚不清楚。在这里，我们优化了基于洗涤剂的重组方案，以开发一种蛋白脂质体技术，该技术将主要的采光复合物II（LHCII）结合到成分明确的大型单层脂质双层囊泡中，以研究MGDG对LHCII采光的影响。使用稳态荧光光谱，CD光谱和与时间相关的单光子计数，我们发现，叶绿素荧光量子产率和荧光寿命都清楚地表明，脂质双层中MGDG的存在将LHCII从光捕获切换为更多的能量猝灭模式，从而将收获的光耗散为热量。假设在这里开发的体外系统中，MGDG通过调节LHCII结合的外周色素在脂质双层中的静液压侧膜压力分布来控制LHCII的光收集。