Understanding the role of carotenoids in bacterial light-harvesting proteins

该项目将量化“光收集”（LH）蛋白如何保护光合生物免受强烈阳光的照射，这一过程被称为“光保护”。为此，我们将使用我们团队最近开发的LH蛋白的转基因版本和人工生物膜。这些LH蛋白自然定位于光合细菌或植物叶绿体中发现的特殊生物膜中。明亮的阳光会对植物和光合细菌造成伤害，因此，为了防止这种情况发生，它们启动了光保护过程，安全地去除多余的能量。这一过程对植物和光养细菌的适应性至关重要，但我们对它的了解还存在空白。我们知道类胡萝卜素色素参与其中，LH蛋白的聚集也增加了能量耗散，但分子细节尚不确定。该项目将通过比较光合细菌的LH蛋白和植物的LH蛋白，来确定这两个因素（类胡萝卜素和蛋白质聚类）是如何引起光保护的。样品将用世界一流的显微镜和光谱仪器进行分析。首先，在最简单的分离蛋白情况下，我们将评估LH蛋白的能量耗散与类胡萝卜素含量之间的关系。其次，我们将评估能量耗散如何与使用人工生物膜的蛋白质聚类和类胡萝卜素的双重效应相关，这为我们提供了对系统的更好控制。第三，我们将评估天然生物膜，并将其与人工生物膜进行比较，以显示更复杂的天然系统是否有其他因素改变LH蛋白的行为。揭示植物和细菌如何控制LH膜内能量分布的共同分子机制将有助于我们理解太阳能捕获的关键阶段，这是光合作用全球过程的基础。这可能会提供新的信息，帮助其他研究人员开发产量更高的改良作物。

This project will quantify how "light-harvesting" (LH) proteins can protect photosynthetic organisms from exposure to intense sunlight, in a process called "photo-protection". To do this, we will use genetically-modified versions of the LH proteins and artificial biomembranes that were recently developed by our team. These LH proteins are naturally localised within specialised biomembranes found in photosynthetic bacteria or plant chloroplasts. Bright sunlight can cause damage to plants and photosynthetic bacteria, so, to prevent this they activate photo-protective processes which safely remove the excess energy. This process is essential for fitness of plants and phototrophic bacteria but there are gaps in our knowledge of it. We know that carotenoid pigments are involved and also that the clustering of LH proteins increases energy dissipation, but the molecular details are uncertain. This project will determine how these two factors (carotenoids and protein clustering) can cause photo-protection by comparing LH proteins from photosynthetic bacteria to LH proteins from plants. Samples will be analysed with a world-class suite of microscopy and spectroscopy instruments. Firstly, we will assess how energy dissipation in the LH proteins is related to their carotenoid content for the simplest situation of isolated proteins. Secondly, we will assess how energy dissipation relates to the dual effects of protein clustering and carotenoids using artificial biomembranes which offer us greater control over the system. Thirdly, we will assess natural biomembranes and compare these to the artificial biomembranes to show whether the more complicated native system has other factors which alter the behaviour of LH proteins. Revealing the shared molecular mechanisms for how plants and bacteria control the distribution of energy within LH membranes will help us to understand the critical stages of solar energy capture which are fundamental to the global process of photosynthesis. This could provide new information that helps other researchers develop improved crops that have higher yields.