Cryo-EM structure of spinach photosystem II-LHCII supercomplex at 3.2 Å resolution

Xuepeng Weia,b, Xiaodong Sua, Peng Caoa, Xiuying Liua, Wenrui Changa, Mei Lia, Xinzheng Zhanga, Zhenfeng Liua
aNational Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; 2University of Chinese Academy of Sciences, Beijing 100049, China.

In plants photosynthesis, PSII (photosystem II) is fueled by a series of LHCIIs (Light harvesting complex II) associated with it at the peripheral region.The energy tranfer pathways from LHCII to PSII are to be investigated in detail on the basis of a high resolution structure of PSII-LHCII supercomplex. Here we present the structure of C2S2-type (C, PSII core, S, strongly bound LHCII) spinach PSII-LHCII supercomplex at 3.2 Å resolution. The structure was determined by cryo-electron microscopy through the single-particle reconstruction method. The result reveals several remarkable features of plant PSII-LHCII structure: (i) Three different LHCIIs, namely major LHCII trimer, CP26 and CP29 have been located adjacent to CP43 or CP47. The structures of CP26 and full-length CP29 with its N-terminal region have been solved; (ii) Four extrinsic subunits (PsbO, PsbP, PsbQ and PsbTn) have been located on the luminal domain of the supercomplex; (iii) Three small intrinsic subunits responsible for the assembly between LHCIIs and PSII core have been identified; (iv) The arrangement of chlorphylls at the interfaces between LHCIIs and PSII core has been deciphered and the potential energy transfer pathways are suggested.

Figure:  Cryo-EM density map of spinach PSII-LHCII supercomplex at 3.2 Å resolution. (a) PSII-LHCII supercomplex viewed from stromal side; (b) PSII-LHCII supercomplex viewed along membrane plane.


[1]    Wei, X., Su, X., Cao, P., Liu, X., Chang, W., Li, M., Zhang, X., and Liu, Z. (2016). Structure of spinach photosystem II–LHCII supercomplex at 3.2 Å resolution. Nature  DOI: 10.1038/nature18020.