Abstract
DNA microarray analysis revealed salt stress enhances the expression of several HSP genes in Synechocystis sp. PCC 6803. Higher enhancement in the case of hspA suggested its role in the protection from salt stress. As a consequence, we studied a deletion mutant of hspA (HK-1) at various salt stresses and examined the expression patterns of some of the HSP genes. To our surprise, HK-1, survived to a higher level after a direct lethal salt treatment, constitutively accumulating higher level of groESL1 and groEL2 transcripts at 30oC, compared to wild type. However, HK-1 failed to acquire tolerance by moderate salt pretreatment in contrast with wild-type cells. Salt stress influenced groEL2, htpG and dnaK2 transcript accumulation by specific stabilization of these transcripts. Electron micrographs at various salt stresses showed HK-1 failed to undergo changes in ultrastructure that wild-type cells experienced. This further confirms the role of hspA in salt stress management.
