Understanding the role of carotenoids in bacterial light-harvesting proteins

点击翻译按钮获取中文摘要

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.