Regulation of Photosystem Composition in the Cyanobacterial Photosynthetic System: the Regulation Occurs in Response to the Redox State of the Electron Pool Located between the Two Photosystems

摘要

Regulation of electron transport composition was studied withSynechocystis (Aphanocapsa)PCC 6714 grown under various trophic conditions. Photosystem (PS) composition,PS I/IIratio, was used as the index for the composition of the electron transport system. Special attention was paid to the relationship between changes in thePS I/IIratio and features of electron transport. Results indicated that (1) the change of composition of the electron transport system is induced not only by the light conditions but also by changes in the electron influx and efflux. (2) The change occurs so as to relieve the imbalance between the electron influx and the efflux, caused by changes in the conditions for the electron transport, and (3) the redox state of plastoquinone pool is probably related to the primary stimulus of the regulation.