Identification of two genes, sll0804 and slr1306, as putative components of the CO2-concentrating mechanism in the cyanobacterium Synechocystis sp. strain PCC 6803

Insertional transposon mutations in the sll0804 and slr1306 genes were found to lead to a loss of optimal photoautotrophy in the cyanobacterium Synechocystis sp. strain PCC 6803 grown under ambient CO₂ concentrations (350 ppm). Mutants containing these insertions (4BA2 and 3ZA12, respectively) could grow photoheterotrophically on glucose or photoautotrophically at elevated CO₂ concentrations (50,000 ppm). Both of these mutants exhibited an impaired affinity for inorganic carbon. Consequently, the Sll0804 and Slr1306 proteins appear to be putative components of the carbon-concentrating mechanism in Synechocystis sp. strain PCC 6803.