Our analyses of the mutants lacking Cph1 and Cph2 demonstrate that phytochrome-like proteins are not involved in the general ability of Synechocystis cells to move toward a light source. Inactivation of cph1 in Synechocystis sp. PCC6803 resulted in a pleiotropic phenotype. Growth of the mutants was inhibited under high and far red light. Cph2 knockout mutants showed a reduced growth under red light.
Double mutants behave similar to the single gene knockouts.
Our data strongly suggest a function of the Synechocystis phytochromes in acclimation to higher irradiances as well to red and far red light. Proteome analyses revealed a few distinct differences between wild-type and mutant cells.