Revealing the mechanism of photoprotection in light-harvesting proteins using novel nanotechnology and advanced time-resolved fluorescence microscopy

The Light-Harvesting Complex II (LHCII) is the major antenna protein found in green plants and is essential for efficient photosynthesis. It has a crucial role in absorbing solar photons and channelling this energy to the next part of the system and also a secondary role in protecting the biological organism from high intensity sunlight by safely dissipating excess energy. However, the molecular mechanism for the process of photoprotective energy dissipation within LHCII is highly debated and varies between different organisms. This project will use our latest developments in membrane nanotechnology and world-class microscopy and spectroscopy to advance our understanding of the true nature of photoprotection in LHCII.

The laboratory in Leeds recently developed a new technique to control the organization of membrane proteins within a model lipid bilayer by applying electric fields. The proteins can be visualized by a specialized fluorescence microscope that also acquires fluorescence lifetimes to measure the energetic state of the LHCII. This combination of techniques provides a new way to assess protein-protein interactions and correlate them to possibility of energy dissipation in LHCII. This project will compare a systematic series of samples with these techniques: (i) comparison of different LH proteins from plants versus bacteria versus algae, (ii) effect of pH and other parameters which are known to trigger photoprotection, (iii) effect of key modulator proteins with LHCII that are known to modulate photoprotection (e.g., PsbS). The outcome of these investigations will be a quantitative model for how various LH proteins can trigger photoprotection. This project will provide a major advance in our understanding of photosynthesis with wider relevance to bioenergy and agriculture.