Dissertation defence (Molecular Plant Biology): MSc Azfar Ali Bajwa

MSc Azfar Ali Bajwa defends the dissertation in Molecular Plant Biology titled “DIVERSITY IN PHOSPHORYLATION OF THYLAKOID MEMBRANE PROTEINS IN CHLOROPLASTS” at the University of Turku on 09 April 2024 at 12.00 (University of Turku, Main building, Säästöpankki lecture hall, Turku).

Opponent: Professor Agnieszka Mostowska (University of Warsaw, Poland)
Custos: Professor Eevi Rintamäki (University of Turku)

Doctoral Dissertation at UTUPub: https://urn.fi/URN:ISBN:978-951-29-9650-6


Summary of the Doctoral Dissertation:

Photosynthesis is essential to life on Earth. It converts solar energy into chemical energy that supports our lives as food, feed and fuel, and also produces the oxygen we breathe. The efficiency of photosynthesis is therefore a key determinant for bioproduction capacity, which is highly dependent on environmental conditions that prevail in the natural habitats of plants, and can vary greatly in both the short and long term. Changing light conditions together with other environmental stresses may severely damage the photosynthetic apparatus in chloroplasts. Nevertheless, plants have developed a number of different, partially species-specific, regulation mechanisms to avoid light-induced damages to photosynthetic apparatus. My thesis explores the regulation of photosynthesis through protein phosphorylations, mainly by thylakoid-associated protein kinases, both in a moss (Physcomitrium patens, an early land plant) and in an angiosperm (Arabidopsis thaliana, a flowering plant model species).

My research on mosses elucidated several changes in regulation of photosynthesis that occurred upon transitioning of photosynthetic organisms from water to terrestrial environment. I gained evolutionary insights into kinases, such as STN7 and STN8, and their target proteins, and discovered that mosses employ a distinct strategy to avoid excessive sunlight compared to flowering plants. Notably, I found that the formation of a moss-specific PSI Large protein complex relies on the phosphorylation of specific LHCBM proteins by the STN7 kinase.

Arabidopsis research explored the dynamics and phosphorylation of photosynthetic proteins under changing light conditions, in comparison to that occurring in Physcomitrella. Specifically, I found that a specific protein called CURT1B, and its phosphorylation, contributes to the fine-tuning of thylakoid membrane ultrastructure and function in response to different light conditions. Additionally, I discovered that calcium signaling, along with thylakoid protein phosphorylations, modulates the key proteins involved in the repair of thylakoid protein complexes. My research identifies new targets for studying photosynthesis and shows how calcium and protein phosphorylation co-operate in chloroplasts.

My research helps in understanding the regulation of photosynthesis, provides new tools for photosynthesis research and will thereby contribute to engineering photosynthetically resilient organisms to cope with changing environmental conditions for improving the production of food, feed and renewable energy.
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