Sll0396 regulates transcription of the phycocyanin genes in Synechocystis sp. PCC 6803

Abstract

An olive-green mutant was generated in Synechocystis sp. strain PCC 6803 by inactivation of the sll0396 gene. Whole-cell absorption spectra of the mutant revealed the missing of phycocyanin peak. An investigation of the low-temperature fluorescence emission spectra revealed that the sll0396X mutant has a reduced amount of phycocyanin. Western blot analysis showed that the mutant contained less phycocyanin b-and a-subunits and lacked the 30-and 32-kDa linker polypeptides, and northern blot analysis revealed that the transcription of the 1.4-kb cpcBA gene encoding the phycocyanin b-and a-subunits was lower in the mutant. The Sll0396 protein has a DNAbinding motif and shares homology with known response regulators. Our results indicate that Sll0396 plays a regulatory role in the transcription of the phycocyanin genes during phycobilisome synthesis.