PSII-LHCII supercomplex organizations in photosynthetic membrane by coarse-grained simulation

J Phys Chem B. 2015 Mar 12;119(10):3999-4008. doi: 10.1021/jp511277c. Epub 2015 Mar 2.

Abstract

Green plant photosystem II (PSII) and light-harvesting complex II (LHCII) in the stacked grana regions of thylakoid membranes can self-organize into various PSII-LHCII supercomplexes with crystalline or fluid-like supramolecular structures to adjust themselves with external stimuli such as high/low light and temperatures, rendering tunable solar light absorption spectrum and photosynthesis efficiencies. However, the mechanisms controlling the PSII-LHCII supercomplex organizations remain elusive. In this work, we constructed a coarse-grained (CG) model of the thylakoid membrane including lipid molecules and a PSII-LHCII supercomplex considering association/dissociation of moderately bound-LHCIIs. The CG interaction between CG beads were constructed based on electron microscope (EM) experimental results, and we were able to simulate the PSII-LHCII supramolecular organization of a 500 × 500 nm(2) thylakoid membrane, which is compatible with experiments. Our CGMD simulations can successfully reproduce order structures of PSII-LHCII supercomplexes under various protein packing fractions, free-LHCII:PSII ratios, and temperatures, thereby providing insights into mechanisms leading to PSII-LHCII supercomplex organizations in photosynthetic membranes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Light-Harvesting Protein Complexes / chemistry*
  • Light-Harvesting Protein Complexes / metabolism
  • Microscopy, Electron
  • Molecular Dynamics Simulation
  • Photosynthesis
  • Photosystem II Protein Complex / chemistry*
  • Photosystem II Protein Complex / metabolism
  • Protein Structure, Quaternary
  • Temperature
  • Thylakoids / metabolism

Substances

  • Light-Harvesting Protein Complexes
  • Photosystem II Protein Complex