Green plant photosystem I binds light-harvesting complex I on one side of the complex

Biochemistry. 2001 Jan 30;40(4):1029-36. doi: 10.1021/bi0015358.


We report a structural characterization by electron microscopy of green plant photosystem I solubilized by the mild detergent n-dodecyl-alpha-D-maltoside. It is shown by immunoblotting that the isolated complexes contain all photosystem I core proteins and all peripheral light-harvesting proteins. The electron microscopic analysis is based on a large data set of 14 000 negatively stained single-particle projections and reveals that most of the complexes are oval-shaped monomers. The monomers have a tendency to associate into artificial dimers, trimers, and tetramers in which the monomers are oppositely oriented. Classification of the dimeric complexes suggests that some of the monomers lack a part of the peripheral antenna. On the basis of a comparison with projections from trimeric photosystem I complexes from cyanobacteria, we conclude that light-harvesting complex I only binds to the core complex at the side of the photosystem I F/J subunits and does not cause structural hindrances for the type of trimerization observed in cyanobacterial photosystem I.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chlorophyll / chemistry
  • Chromatography, Gel
  • Dimerization
  • Immunoblotting
  • Light-Harvesting Protein Complexes
  • Microscopy, Electron
  • Photosynthetic Reaction Center Complex Proteins / chemistry*
  • Photosynthetic Reaction Center Complex Proteins / immunology
  • Photosynthetic Reaction Center Complex Proteins / ultrastructure
  • Photosystem I Protein Complex
  • Spinacia oleracea / chemistry*
  • Thylakoids / chemistry
  • Thylakoids / immunology
  • Thylakoids / ultrastructure


  • Light-Harvesting Protein Complexes
  • Photosynthetic Reaction Center Complex Proteins
  • Photosystem I Protein Complex
  • Chlorophyll