Construction and characterization of deletion mutants of acid stress-induced genes in Synechocystis sp. PCC 6803

Abstract

We have reported the changes in gene expression accompanying the acid-stress response of Synechocystis sp. PCC 6803 using DNA microarrays. By comparison of expression profiles from both cells treated at pH 3.0 and normal pH condition (pH 8.0), we found about 30 genes up-regulated more than 3-fold in their expression after the acid treatment. Among these genes, slr0967 and sll0939 were continuously increased by 12 and 20-fold at 4 hr under the stress. Analysis of the deletion mutants of these genes showed that these two genes play important roles in acid tolerance. In this work, we constructed 7 deletion mutants in addition to two deletion mutants and analyzed their phenotypes. In these deletion mutants, 3 mutants were found to be sensitive to acid treatment but 4 mutants not. We will discuss the photosynthetic properties and the gene expression under various stresses of these deletion mutants.