Transcriptional regulator PrqR plays a negative role in glucose metabolism and oxidative stress acclimation in Synechocystis sp. PCC 6803

Abstract

Plant and cyanobacteria can perceive signals from soluble sugar and reactive oxygen species (ROS) and then coordinate gene expression under stress acclimation, but the underlying mechanism remains unclear. In this study, we found that the transcriptional factor PrqR (Slr0895) in Synechocystis can perceive signals from ROS generated after shifting from prolonged darkness with glucose into high-light. The deletion mutant (DprqR) showed increased growth rate and decreased ROS content, whereas the complementary strain (CprqR) restored the growth characteristics, phenotypes and ROS status of WT, thereby establishing PrqR as a negative regulator of ROS.LC/GC-MS-based metabolic profiling also showed active ROS mitigation in DprqR mutant. Further study by qRT-PCR, ChIP-PCR and deletion of both prqR and prqA (DprqR-DprqA mutant) revealed that PrqR exerts this negative regulation of ROS removal by controlling the expression of sodB and prqA (slr0896). Furthermore, PrqR also found to control glucose metabolism by regulating a positive regulator of glucose metabolism, sigE, and its regulons. Results suggest that PrqR was involved in perceiving signals from ROS under physiological condition, as well as in regulating stress removal and glucose metabolism.

Integrative analysis of the salt stress response in cyanobacteria

“…Hence, it is tempting to speculate that PrqR might be involved in the salt-stimulated expression of ggpS and other genes in this putative regulon. PrqR was reported as repressor for genes involved in glucose metabolism and oxidative stress acclimation [ 39 ]. The LexA protein, which is not changed on protein level but became significantly decreased on RNA level (Additional file 3 : Fig.…”

Inactivation of the RNA helicase CrhR impacts a specific subset of the transcriptome in the cyanobacterium Synechocystis sp. PCC 6803

“…Altered levels of the sigma factor sigE (sll1689), the sugar catabolism regulator Rre37 (sll1330), the negative regulator of glucose metabolism and oxidative stress acclimation PrqR (slr0895) and also PmgR1 (ncr0700) suggest an interesting link between CrhR and sugar/energy/heterotrophic metabolism, which is the major functional target category of these regulators [43][44][45][46][47]. PmgR1 (ncr0700), the most strongly induced sRNA in crhR TR , is involved in the switch to photomixotrophic growth and the regulation of glycogen metabolism [48].…”

Integrative analysis of the salt stress response in cyanobacteria

“…Hence, it is tempting to speculate that PrqR might be involved in the salt-stimulated expression of ggpS and other genes in this putative regulon. PrqR was reported as repressor for genes involved in glucose metabolism and oxidative stress acclimation (Khan et al, 2016). The LexA protein, which is not changed on protein level but became significantly decreased on RNA level (Suppl.…”

“…S6). It has been recently shown that PrqR is involved in the acclimation to oxidative stress in Synechocystis 6803 (Khan et al, 2016). Salt stress is also inducing oxidative stress in cyanobacterial cells, hence, the finding of the role of PrqR in this stress acclimation process might of secondary importance.…”