Slr1923 of Synechocystis 6803 Is Related to Chlorophyll a Metabolism

Abstract

A mutant in which the gene slr1923 was inactivated has been created in Synechocystis sp. PCC 6803. The mutant had a slower growth rate compared with WT under normal condition (3% CO2 + 100 μE m−2 s−1). The mutant did not grow under high-light (300 μE m−2 s−1). The chlorophyll content of the cell has been reduced drastically in the mutant. It was also of note that the absorptionmaximum of the Soret band of chlorophyll was shifted toward longer wavelengths by about 6 nm, while the red band was not changed.The retention time of chlorophyll a was shorter than that of wild type by HPLC analysis, suggesting a modified chlorophyll a species in the mutant. A high fluorescence intensity at 77 K peaking at about 685 nm suggests miss-connection and/or decreasedefficiency of energy transfer from phycobilisomes to PSII. Further experiments are going on to indicate that the protein Slr1923might be linked to chlorophyll a metabolism in Synechocystis 6803.