GSE192357
Roles of close homologues SigB and SigD in heat and bright light acclimation of the cyanobacterium Synechocystis sp. PCC 6803
Acclimation of cyanobacterium Synechocystis sp. PCC6803 to suboptimal conditions is largely dependent on adjustments of gene expression, which is highly controlled by the s factor subunits of RNA polymerase (RNAP). The SigB and SigD s factors are close homologues. Here we show that sigB and sigD genes are both induced in bright light and high temperature stresses. Comparison of transcriptomes of the control strain (CS), ?sigB, ?sigD, ?sigBCE (SigD is an only functional group 2 s factor), and ?sigCDE (SigD is an only functional group 2 s factor) strains in standard, bright light and high temperature conditions revealed that the SigB and SigD factors regulate different set of genes, and that SigB and SigD regulons are highly dependent on stress conditions. The SigB regulon is bigger than the SigD regulon at high temperature, whereas in bright light the SigD regulon is bigger the SigB regulon. Furthermore, our results show that favoring the SigB or SigD factor by deleting other group 2 s factors do not lead to superior acclimation to bright light or high temperature conditions, indicating that all group 2 s factors play roles in acclimation processes. Overall design: The 30-ml cell cultures (Synechocystis sp. PCC 6803 were grown in standard condition to OD730 ~ 1, cells were collected from the standard conditions, or treated for 1h at the PPFD of 750 µmol photons m-2 s-1 or 1h at 42 °C maintaining the other condition same as in the standard conditions. 15-ml of cell suspension was pour to pre-frozen centrifugation tube, and cell pellet was collected by centrifugation at 7000 g for 5min at 4 °C. Three independent experiments were performed at each conditions.