第1240回生物科学セミナー

Assembly and Energy Transfer Pathways between Plant Light-Harvesting Complexes II and Photosystems

Zhenfeng Liu, Ph.D.(Chinese Academy of Sciences)

2018年12月03日(月)    14:00-15:00  理学部1号館東棟 380号室   

Oxygenic photosynthesis, a remarkable biological process sustaining all kinds of living organisms on the earth, depends on the functions of light-harvesting complexes and two photosystems (photosystems II and I, PSII and PSI) to carry out the initial photophysical and photochemical reactions. In plants, the major and minor light-harvesting complexes II (LHCII, CP29, CP26 and CP24) absorb photon energy and transfer the excitation energy to PSII to induce charge separation in the reaction center. Recently, we have solved the structures of plant PSII-LHCII supercomplexes of the C2S2 and C2S2M2 types (C: PSII core; S: strongly associated LHCII; M: moderately associated LHCII) at near-atomic resolution through single-particle cryo-electron microscopy (Cryo-EM) method[1,2]. The high-resolution structures reveal the mechanism of specific assembly between the peripheral antenna complexes and PSII core. At their interfaces, numerous closely-connected chlorophyll pairs form the basis for mediating energy transfer from LHCII/CP29/CP26/CP24 to PSII core. Furthermore, the structure of phosphorylated LHCII in complex with PSI[3] reveals their specific interactions and the interfacial energy transfer pathways crucial for state transitions, a light-harvesting regulation process serving to balance the excitation levels of two photosystems under fluctuating light conditions.

References:
[1] Wei, X. P. et al. Nature 534, 69-74, 2016.
[2] Su, X.D. et al. Science 357, 815-820, 2017.
[3] Pan, X.W. et al. Science 360: 1109-1113, 2018