Chromatic Regulation of Photosystem Composition in the Cyanobacterial Photosynthetic System: Kinetic Relationship between Change of Photosystem Composition and Cell Proliferation

摘要

Kinetics of the change of photosystem (PS) composition in cyanobacteria induced by chromatic light were studied in relation to cell proliferation. The study was made for two unicellular strains,SynechococcusNIBB 1059 andSynechocystis (Aphanocapsa) PCC 6714. We found that (1) the change to a higher or lower PS I/II ratio was due to acceleration or suppression of apparent PS I formation, and (2) it progressed on a similar time scale to that of the cell proliferation. The apparent rate constant of the change in the PS I/II ratio was proportional to that of cell proliferation,μ, when this was low, but at high values ofμthe increase in the rate constant of the change in the PS I/II ratio became smaller, causing a deviation from the linear relationship. Results indicate that under autotrophic conditions, the photoregulated composition change occurs as a result of thylakoid development, which accompanies cell proliferatio