Excitation energy transfer in aggregates of Photosystem I and Photosystem II of the cyanobacterium Synechocystis sp PCC 6803: Can assembly of the pigment-protein complexes control the extent of spillover?

The fluorescence profile of Photosystem I/Photosystem II mixtures in differ ent solvent systems shows that both non-hydrophobic and hydrophobic interac tions govern their association and control energy transfer from Photosystem II to Photosystem I. The non-hydrophobic interactions lead to a highly eff icient excitation energy transfer from Photosystem II to Photosystem I. In view of this, we propose that similar non-hydrophobic interactions, between the Photosystem II and Photosystem I peripheral proteins, also play a sign ificant role in their association in thylakoids that control state transiti ons in cyanobacteria.