Periodic Reporting for period 1 - TOC-maker (The assembly and structure of the chloroplast protein import machinery in plants)
Periodo di rendicontazione: 2021-04-01 al 2023-03-31
1.2 Why is it important for society? The human population is growing rapidly and is predicted to reach approximately 10 billion by 2050 due to advancements in medical and economic developments as well as inadequate control measures on population growth. In addition, climate change due to anthropogenic activities exacerbates pressure on food security and natural resources. It is clear that a major challenging task of our era is to deliver increased agricultural production with resilience to environmental stresses and disease. To meet this challenge, we must develop improved crops, by delivering and then exploiting advances in our understanding of key areas in plant sciences.
1.3 What are the overall objectives? My research aim in this project was to elucidate the biogenesis, assembly, and structure of TOC complexes in plant chloroplasts, in fine molecular detail. My specific objectives were as follows: (i) Identification of assembly factors for, and elucidation of the assembly process of, TOC complexes; (ii) Structural determination of the TOC-P complex at high resolution by cryo-electron microscopy. In addition, as an MSCA-IF project, another aim was to foster my development as an independent researcher.
2.2 Results achieved so far: This project provided novel insights and mechanistic details concerning the biogenesis and assembly of the TOC complex. We revealed that the central core component of the TOC complex is the master player in the biogenesis of the TOC complex, controlling the assembly and stability of all the peripheral receptor proteins; it forms a photosynthetic-type TOC configuration (TOC-P) in green chloroplasts, and a non-photosynthetic-type TOC configuration (TOC-NP) that is abundant in non-green plastids. Functionally, the preference for different substrates for protein import is the key difference between TOC-P and TOC-NP. We proposed the step-wise assembly of the TOC complex in chloroplasts, in which the central core component is the initial component in the assembly of the TOC complex, followed by its stabilization with a small peripheral subunit. In the final step, a large peripheral protein is then integrated to form a fully mature TOC complex. Our structural investigation of the plant TOC complex by cryo-electron microscopy is extended beyond the timeline of this fellowship; however, I have developed an advanced pipeline.
2.3 Exploitation and dissemination. The results of this project were thoroughly discussed within the group and departmental seminars organized monthly or annually at the Department of Biology, Oxford. Prof Paul Jarvis (PI) and I have presented the results of this project at national (Plastid Preview – 2023, Oxford) and international (EMBO meeting on Protein translocation – 2022, Spain) conferences. A further major route of dissemination is via publication; I have already published a review article in J. Cell Sci. (2023), and I am preparing a manuscript to submit to Nature Commun. or PNAS. I will update my discoveries on the lab’s webpages and/or social media, which are well viewed; and I will communicate the work to the general public by interacting with the mainstream media when opportunities arise (e.g. via the University’s News and Information Office). All research publications arising from the project will be deposited in the Oxford Research Archive, which is freely accessible. With regard to exploitation, I will take care to protect (e.g. by patent applications) new intellectual property coming from the project using procedures already established in the host laboratory. Because of the vital role that chloroplasts (and by extension chloroplast protein import) play in plant growth, productivity, and stress tolerance, the new information my work generates may enable novel crop improvement strategies.