Reconstruction of the chloroplast noncyclic electron transport pathway from water to NADP with three integral protein complexes.

RECONSTRUCTION OF PHOTOSYNTHETIC NONCYCLIC ELECTRON TRANSPORT FROM WATER TO NADP HAS BEEN ACCOMPLISHED BY USING THREE INTEGRAL PROTEIN COMPLEXES ISOLATED FROM CHLOROPLAST THYLAKOID MEMBRANES: photosystems I and II and the cytochrome b(6)-f complex. This system shows an absolute dependence on the presence of all three protein complexes for NADP reduction, in addition to plastocyanin, ferredoxin, and ferredoxin-NADP reductase. The reconstructed system was found to be sensitive to low concentrations of known inhibitors of noncyclic electron transport. Depletion of the Rieske iron-sulfur center and bound plastoquinone from the cytochrome b(6)-f complex resulted in an inhibition of the photoreduction of NADP.