Characterization of a Giant PSI Supercomplex in the Symbiotic Dinoflagellate Symbiodiniaceae.

摘要: Symbiodiniaceae are symbiotic dinoflagellates that provide photosynthetic products to corals. Because corals distributed across a wide range of depths in the ocean, species must adapt various light environments optimize their performance. However, as few biochemical studies photosystems have been reported, molecular mechanisms photoadaptation this algal family remain poorly understood. Here, investigate machineries Symbiodiniaceae, we purified and characterized PSI supercomplex from genome-sequenced Breviolum minutum (formerly Symbiodinium minutum). Mass spectrometry analysis revealed 25 light-harvesting complexes (LHCs), including both LHCF LHCR families, PSI-LHC supercomplex. Single-particle electron microscopy showed unique giant structures were associated with LHCs. Moreover, contained significant amount xanthophyll cycle pigment diadinoxanthin. Upon high treatment, B. cells increased nonphotochemical quenching, which was correlated conversion diadinoxanthin diatoxanthin, occurring preferentially The possible role photoprotection is discussed.