Evaluation of Acid Stress Tolerance in Synechocystis sp. PCC 6803 Mutants Lacking Signal Transduction-Related Genes sigB, sigD, and rre15

Genes Upregulated By Acid Stress In Cyanobacteria Synechocystis Sp. Pcc 6803 (Photosynthesis Research 84, 225–230, 2005) Have Been Identified By Dna Microarray Analysis. Among These Genes, Our Focus Is On Sigb, Sigd, And Rre15, Which Are Involved In Signal Transduction And Investigated The Impact Of These Genes‘ Null Mutation On The Survival Of Synechocystis Cells In A Low-Ph Medium. The Survival Rates Of Sigb And Sigd Mutants At Ph 6 Were Lower Than The Survival Rates Of Wild-Type Cells. Quantitative Real-Time Rt-Pcr Revealed That Sigb Expression Was 47% In The ΔSigd Mutant Compared With Wild-Type Cells. These Results Suggest That Sigb And Sigd Are Required For Acid Tolerance, And That Sigd Is Located In The Upstream Of The Signal Transduction Pathway Of Acid Stress Response In The Synechocystis Sp. Pcc 6803 Compared With Sigb.