Dinoflagellates are one of the important eukaryotic phytoplankton groups in marine ecosystems. Dinoflagellates are the main contributors to primary productivity, as well as the main group that triggers harmful red tides and produces marine toxins. Chlorella and other dinoflagellates play an important role in maintaining the ecological balance of coral reefs through mutual symbiosis with coral polyps. Dinoflagellates have evolved light systems and light harvesting antennas that are different from other algae and plants, and combined with carotenoids such as chlorophyll c and polymethemodin in diatom groups to better adapt to the complex and changing marine light environment. However, there has been a lack of research on the light system and light harvesting skyline of dinoflagellates. Therefore, exploring the structure and light harvesting mechanism of the light harvesting antenna and light system of dinoflagellates is of great ecological value and scientific significance for revealing the light energy utilization and light adaptation mechanism of marine dinoflagellates.
The Research Group of Photosynthetic Membrane Protein Structural Biology of the Institute of Botany, Chinese Academy of Sciences has explored the structural characteristics and light harvesting mechanism of the three photosystem I (PSI) - chlorophyll (Chls) a/c-polychlorophyrin light harvesting skyline (PSI-AcpPCI) super complexes of dinoflagellate dinoflagellate, dinoflagellate robusta and symbiotic dinoflagellate zooxanthophyta by using physiological, biochemical and single particle freeze electron microscopy techniques The uniqueness of pigment arrangement. Compared with other eukaryotic photosynthetic organisms, the PSI core PsaA/B subunits of the two dinoflagellates were significantly smaller, lacking more than 20 pigment binding sites; And other PsaD/F/I/J/L/M/R subunits have expanded and developed some new pigment sites, partially compensating for the structural and pigment changes of PsaA/B subunits. These changes may be due to multiple endosymbiosis and chloroplast genome changes experienced during the evolution of dinoflagellates. The light harvesting antenna protein AcpPCI of dinoflagellate has generated some new loop structures and pigment sites to adapt to changes in the core subunit structure of PSI, ensuring sufficient light energy capture and smooth energy transfer, and further forming a protein assembly mode and energy transfer network different from other photosynthetic organisms. The above achievements provide important structures and functional foundations for analyzing the light adaptation mechanisms of marine red tide dinoflagellates and symbiotic dinoflagellates, and provide important clues for exploring the continuous evolution of photosynthetic organisms and designing new autotrophic biological chassis.
On February 6th, the relevant research results were published online in the Journal of the National Academy of Sciences (PNAS). The research work was supported by the National Key Research and Development Program, the National Natural Science Foundation for Outstanding Young Scientists Fund, the Chinese Academy of Sciences Youth Team Program for Stable Support in Basic Research, etc.
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The assembly pattern of the core subunit of the dinoflagellate photosystem I and the structural evolution of its important subunits. Gray displays the conserved secondary structure of the PSI core protein, while color indicates the evolution of new protein fragments in dinoflagellates.
