Relationship between the organization of the PSII supercomplex and the functions of the photosynthetic apparatus

The chlorophyll fluorescence and the photosynthetic oxygen evolution (flash-induced oxygen yield patterns and oxygen bursts under continuous irradiation) were investigated in the thylakoid membranes with different stoichiometry and organization of the chlorophyllprotein complexes. Data show that the alteration in the organization of the photosystem 11 (PSII) supercomplex, i.e. the amount and the organization of the light-harvesting chlorophyll a/b protein complex (LHCII), which strongly modifies the electric properties of the membranes, influences both the energy redistribution between the two photosystems and the oxygen production reaction. The decrease of surface electric parameters (charge density and dipole moments), associated with increased degree of LHCII oligomerization, correlates with the strong reduction of the energy transfer from PSII to PSI. In the studied pea thylakoid membranes (wild types Borec, Auralia and their mutants Coerideovireus 2/16, Costata2/133, Chlorolica XV/1422) with enhanced degree of oligornerization of LHCII was observed: (i) an increase of the So populations of PSII in darkness; (ii) an increase of the misses; (iii) an alteration of the decay kinetics of the oxygen bursts under continuous irradiation. There is a strict correlation between the degree of LHCII oligornerization in the investigated pea mutants and the ratio of functionally active PSII alpha to PSII beta centers, while in thylakoid membranes without oligomeric structure of LHCII (Chlorina f2 barley mutant) the PSII alpha centers are not registered. (c) 2006 Elsevier B.V. All rights reserved.