Abstract
A mutant (slr1923M) of Synechocystis sp. PCC6803 has been created through inactivation of the gene slr1923 and was characterized. The chlorophyll of the mutant is replaced from 3-vinylchlorophyll (normal Chl) to 3,8-divinyl chlorophyll. We have concluded that Slr1923 is related with chlorophyll metabolism and the mutant failed to carry out the reduction of 8-vinyl group of 3,8-divinyl(proto)chlorophyll(ide). In the present study, characterization of reaction centers of the mutant was carried out. Absorption spectra of both the isolated photosystems showed that Soret band peak position shifted to longer wavelength significantly. Compared with wild type, the mutant PSII showed a relatively higher fluorescence peak of 685 nm band at 77K. P700 difference spectra indicated that Soret peak is red shifted which is the same characteristics of divinyl-Chl a absorption spectra. These data confirmed that PSI primary electron donor (P700) is also composed of divinyl-Chl a. Other features will also be reported.
