Periodic Reporting for period 1 - OCPSTRUCTDYNAMICS (Structural dynamics essential for photosynthetic adaptation and survival of cyanobacteria in fluctuating light intensities)
Reporting period: 2020-01-08 to 2022-01-07
Photosynthesis is the primary source of energy in any ecosystem. Solar energy is renewable, non-polluting and available worldwide. Understanding and controlling photosynthetic machinery on a molecular level, in practically in response to environmental changes, is one of the “hot” topics in modern photosynthesis research due to its high potential in green solutions and sustainability.
More than half of photosynthesis occurs in the ocean in single-celled organisms. Cyanobacteria are the antient unicellular photosynthesizes which still contribute up to 50% of oxygen and primary product in the ocean. Therefore, they are excellent model organisms with which to study efficient energy harnessing and storage. Orange Carotenoid Protein (OCP) is a key element in cyanobacterial photoprotection against rapid light increases and works as a light harnessing controller. It is also a unique photoreceptor with peculiar structure: it is the only known photosensor which uses carotenoid for its light-activation. In the scope of OCPSTRUCTDYNAMICS the light-activation steps in OCP were addressed.
More than half of photosynthesis occurs in the ocean in single-celled organisms. Cyanobacteria are the antient unicellular photosynthesizes which still contribute up to 50% of oxygen and primary product in the ocean. Therefore, they are excellent model organisms with which to study efficient energy harnessing and storage. Orange Carotenoid Protein (OCP) is a key element in cyanobacterial photoprotection against rapid light increases and works as a light harnessing controller. It is also a unique photoreceptor with peculiar structure: it is the only known photosensor which uses carotenoid for its light-activation. In the scope of OCPSTRUCTDYNAMICS the light-activation steps in OCP were addressed.
To unravel the exact structural dynamics of light-activation in OCP a multidisciplinary approach was performed: molecular biology tools for creating different OCP constructs were combined with time-resolved spectroscopic studies and X-ray crystallography (static and time-resolved). As a result, spectroscopic signatures and high-resolution structures of OCP photocycle intermediates were for the first time resolved. Time-resolved serial femtosecond crystallography is a relatively new field: So far it has been applied only to understand water splitting in photosynthesis and has never been used to unravel photo switching. In the scope of OCPSTRUCTDYNAMICS this technique was for the first time applied to study OCP photocycle, broadening the horizon for such applications in the future.
This fundamental study may have a long-term impact on Sustainable Development Goals through several applications: 1) Through controlling light harvesting in cyanobacteria, cyanobacterial biofuel production could be increased similar to how it is reported for plants. 2) It will improve our understanding of carotenoid-protein interactions, which could help in understanding and controlling such vital carotenoid photochemical roles such as light-harvesters or antioxidants. Therefore the potential applications range from creating more efficient artificial photosynthesis systems to medical applications.