Abstract
The ATP-binding cassette (ABC) transporters form one of the largest known protein families, and are widespread in bacteria, archaea, and eukaryotes encoded in the largest set of paralogous genes. In Synechocystis sp. PCC6803 genome, over 50 ABC transporter related genes have been found from the genome sequences. The substrates of many other ABC transporters are still unknown. To identify ABC transporters involved in acid tolerance, deletion mutants of other substrate unknown ABC transporter genes were screened for acid stress sensitivities in low pH medium. It has been found that the mutant of slr1045 was more sensitive to acid stress condition than wild type cells. The abundance of expression of slr1045 analyzed under low pH conditions by quantitative real time RT-PCR. Expression of slr1045 in acid stress showed twenty fold higher than that of in the BG-11 medium(pH8.0). When we have examined sensitivities to various stresses (Osmotic, Salt, Pi deficient), the mutant also displayed increased resistant to osmotic stress. Metal contents of wild type cells and the mutant cells were determined using ICP-MS to identity the candidate of the substrate of Slr1045.
