Iron-independent dynamics of IsiA production during the transition to stationary phase in the cyanobacterium Synechocystis sp. PCC 6803.

The cyanobacterial iron stress-induced protein A (IsiA) protein is inducible under many stress conditions. We show that isiA is transcribed during the transition from exponential to the stationary state, translated into protein and incorporated into membranes. Both transcription and translation of isiA demonstrated extraordinary dynamics and was reflected in the formation of IsiA-Chl complexes. We also identified the upstream region of isiA that controlled the CAT activity similar to the regulation of IsiA. The de-repression of isiA during the stationary phase was neither dependent on iron nor a result of oxidative stress.