Assessing the Organization and Photophysics of Light-Harvesting Proteins using Model Lipid Membranes

Natural photosynthetic “thylakoid” membranes found in green plants contain a large network of photosynthetic proteins that regulate light absorption and conversion into chemical and electrical energy. The arrangement of these proteins dictates the energy flow through the membrane, and changes to protein organization can “open” or “close” energy transfer pathways between proteins. By increasing our understanding of this system, we can inform other areas of plant-based research, such as increasing crop yields, or the development of plant-based photovoltaics.

To study the relationship between protein organization and energy transfer, a new form of hybrid membranes was recently developed. These hybrid membranes self-assemble from synthetic lipids and fragmented thylakoid bio-membranes, such that a complete network of photosynthetic proteins is potentially available for analysis. A combination of fluorescence lifetime imaging, and atomic force microscopy was used to interrogate the behaviour of proteins, revealing the protein organization, photophysical state and the mechanism of protein incorporation into the membranes. In another avenue of research, we are developing methods that use electric fields to control and direct the movement of charged biomolecules within membranes. We aim to develop a complete understanding between protein organization and energy transfer by using video-speed measurements to track protein rearrangement and changes to energy transfer in real time. The ability to precisely and reversibly manipulate energy flow in photosynthetic membranes has potential applications in developing light-harvesting nanotechnologies with bespoke photophysical properties.

Video URL: https://youtu.be/3hHJm8_7pP4

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