Effects of CF(0) Proton Flow on the Distribution of Light Energy Between PSI and PSII

The Influence of energy transfer inhibitors of ATP synthase on the chlorophyll fluorescence quenching of thylakoids was studied by the saturation pulse method. Triphenyltin chloride (TPT) treatment could result in an increase of q(Q) and a decrease of q(E) of the thylakoids, but DCCD could not. This increase could be abolished when the deltapH across the thylakoid membrane was dissipated by uncouplers (1O mM NH(4)Cl plus 1&mgr;M nigericin) or in higher salt medium which could relieve localized protons on the thylakoid membrane. In the electron transport system of H(2)O right curved arrow PD(0X) or H(2)O right curved arrow PBQ coupled with PSII. The stimulatory effect of TPT on q(Q) also diminished. By the methods of modulated fluorescence and low temperature fluorescence measurement we observed that TPT markedly increased the imbalance of the distribution of light energy between PSI and PSII in favor of PSII. These results suggest that the CF(0) proton flow could influence the light energy distribution between the two photosystems. This might be materialized by the regulation of the membrane-localized protons on the photochemical efficiency of photosystem II.