Acid Stress responsive genes, slr0967 and sll0939, are directly involved in low-pH tolerance of cyanobacterium synechocystis sp. PCC6803

Abstract

Genes expressed in response to low-pH stress in unicellular cyanobacterium Syechosystis sp. PCC 6803 were identified using DNA microarrays. Among these, the expression of slr0967 and sll0939 constantly increased during a 4 h acid stress condition [Photosynth Res. 84:225-30 (2005)]. The growth of the two genes deletion mutants on BG-11 media at pH 6.0 was significantly lower than that of wild-type cells. On the other hand, overexpression of the two genes under the control of the trc promoter caused the cells to become tolerant to shortterm acid stress (pH 3.0 for 8 h). Real-time RT-PCR analysis of these mutants revealed that the expression of sll0939 was significantly repressed in the slr0967 deletion mutant. These results suggest that sll0939 are directly involved in low-pH tolerance of cyanobacrerium Syechosystis sp. PCC6803 and slr0967 may have been essential for induction of acid responsive genes.