Diatoms rely on fucoxanthin chlorophyll a/c-binding proteins(FCPs)for light harvesting and energy quenching under marine environments.Here we report two cryo-electron microscopic structures of photosystem I(PSI)with e...Diatoms rely on fucoxanthin chlorophyll a/c-binding proteins(FCPs)for light harvesting and energy quenching under marine environments.Here we report two cryo-electron microscopic structures of photosystem I(PSI)with either 13 or five fucoxanthin chlorophyll a/c-binding protein Is(FCPIs)at 2.78 and 3.20Åresolutions from Thalassiosira pseudonana grown under high light(HL)conditions.Among them,five FCPIs are stably associated with the PSI core,these include Lhcr3,RedCAP,Lhcq8,Lhcf10,and FCP3.The eight additional Lhcr-type FCPIs are loosely associated with the PSI core and detached under the present purification conditions.The pigments of this centric diatom showed a higher proportion of chlorophylls a,diadinoxanthins,and diatoxanthins;some of the chlorophyll as and diadinoxanthins occupy the locations of fucoxanthins found in the huge PSI-FCPI from another centric diatom Chaetoceros gracilis grown under low-light conditions.These additional chlorophyll as may form more energy transfer pathways and additional diadinoxanthins may form more energy dissipation sites relying on the diadinoxanthin-diatoxanthin cycle.These results reveal the assembly mechanism of FCPIs and corresponding light-adaptive strategies of T.pseudonana PSI-FCPI,as well as the convergent evolution of the diatom PSI-FCPI structures.展开更多
基金supported by the National Key R&D Program of China(2021YFA1300403)the Youth Innovation Promotion Association of CAS(2020081)+3 种基金the CAS Project for Young Scientists in Basic Research(YSBR-093)the National Natural Science Foundation of China(32222007)the Innovation Platform for Academicians of Hainan Province(2022YSCXTD0005)the Science&Technology Specific Project in Agricultural High-Tech Industrial Demonstration Area of the Yellow River Delta(2022SZX12).
文摘Diatoms rely on fucoxanthin chlorophyll a/c-binding proteins(FCPs)for light harvesting and energy quenching under marine environments.Here we report two cryo-electron microscopic structures of photosystem I(PSI)with either 13 or five fucoxanthin chlorophyll a/c-binding protein Is(FCPIs)at 2.78 and 3.20Åresolutions from Thalassiosira pseudonana grown under high light(HL)conditions.Among them,five FCPIs are stably associated with the PSI core,these include Lhcr3,RedCAP,Lhcq8,Lhcf10,and FCP3.The eight additional Lhcr-type FCPIs are loosely associated with the PSI core and detached under the present purification conditions.The pigments of this centric diatom showed a higher proportion of chlorophylls a,diadinoxanthins,and diatoxanthins;some of the chlorophyll as and diadinoxanthins occupy the locations of fucoxanthins found in the huge PSI-FCPI from another centric diatom Chaetoceros gracilis grown under low-light conditions.These additional chlorophyll as may form more energy transfer pathways and additional diadinoxanthins may form more energy dissipation sites relying on the diadinoxanthin-diatoxanthin cycle.These results reveal the assembly mechanism of FCPIs and corresponding light-adaptive strategies of T.pseudonana PSI-FCPI,as well as the convergent evolution of the diatom PSI-FCPI structures.
