Microarray analysis and redox control of gene expression in the cyanobacterium Synechocystis sp. PCC 6803.

Expression profiles of Synechocystis sp. PCC 6803 genes in response to growth in iron-deficient versus iron-sufficient media and after 30 min treatment with H(2)O(2) were determined using a full-genome microarray. We used an anova model that accounted for slide and replicate (random) effects as well as dye (a fixed) effects to identify statistically significant, differentially expressed genes that changed by 1.25-fold or greater during each of these experiments. We utilized this microarray data to identify gene clusters that were regulated under these stresses, because we are interested in cellular redox control and the way in which the cell responds to oxidative stresses. We are particularly interested in using differential expression to help determine the function of genes involved in redox control and cluster analysis aids this process. We concentrated on four gene clusters, two of which were similarly affected by both stresses, and two that were only differentially regulated by one of the stresses. We also analysed the regulatory genes that responded to these oxidative stresses and discussed the changes in transcription of the RNA polymerase sigma factors and the other regulatory proteins, many of which represent two-component regulatory systems.