Transcript profiling indicates that the absence of PsbO affects the coordination of C and N metabolism in Synechocystis sp. PCC 6803

Abstract

Transcript profiling of nitrate-grown Synechocystis sp. PCC 6803 PsbO-free mutant cells in comparison to wild-type (WT) detected substantial deviations. Because we had previously observed phenotypical differences between Synechocystis sp. PCC 6803 WT and its corresponding PsbO-free mutant when cultivated with l-arginine as sole N source and a light intensity of 200 mumol photons m(-2) s(-1), we also performed transcript profiling for both strains grown either with nitrate or with l-arginine as sole N source. We observed a total number of 520 differentially regulated transcripts in Synechocystis WT because of a shift from nitrate- to l-arginine-containing BG11 medium, while we detected only 13 differentially regulated transcripts for the PsbO-free mutant. Thus, the PsbO-free Synechocystis mutant had already undergone a preconditioning process for growth with l-arginine in comparison to WT. While Synechocystis WT suffered from growth with l-arginine at a light intensity of 200 mumol photons m(-2) s(-1), the PsbO-free mutant developed only a minor stress phenotype. In summary, our results suggest that the absence of PsbO in Synechocystis affects the coordination of photosynthesis/respiration and l-arginine metabolism through complex probably redox-mediated regulatory pathways. In addition, we show that a comparison of the transcriptomes of nitrate-grown Synechococcus elongatus PCC 7942 WT cells and its corresponding PsbO-free mutant cells resulted in only a few differentially regulated transcripts between both strains. The absence of the manganese/calcium-stabilizing PsbO protein of PSII with an assigned regulatory function for photosynthetic water oxidation causes bigger changes in the transcriptome of the permissive photoheterotrophically growing Synechocystis sp. PCC 6803 than in the transcriptome of the obligate photoautotrophically growing S. elongatus PCC 7942.

Translating Divergent Environmental Stresses into a Common Proteome Response through the Histidine Kinase 33 (Hik33) in a Model Cyanobacterium

“…In addition, repression of PsbO might also contribute to the observed differential expression of proteins in C and N metabolism (supplemental Fig. S2), as previously demonstrated by a psbO-deletion mutant (80). Together, these findings suggest that downregulation of photosynthetic machinery is a general response to divergent type of stresses and is mediated, at least partially, through Hik33.…”

Translating Divergent Environmental Stresses into a Common Proteome Response through Hik33 in a Model Cyanobacterium

“…In addition, repression of PsbO might also contribute to the observed differential expression of proteins in C and N metabolism (Supplemental Fig. S2), as previously demonstrated by a psbO-deletion mutant (80). Together, these findings suggest that downregulation of photosynthetic In contrast, a number of heat shock proteins, chaperons, proteases, and proteins involved in the regulation of intracellular redox states were upregulated in response to Hik33 depletion or abiotic stresses (Fig.…”

A Data Integration and Visualization Resource for the Metabolic Network of Synechocystis sp. PCC 6803

“…The model we present here is an extension of the iJN678 model described in Nogales et al (2012). Pathways that were amended include the tricarboxylic acid cycle (Zhang and Bryant, 2011), Arg metabolism (Schriek et al, 2007(Schriek et al, , 2008(Schriek et al, , 2009, and Pro metabolism (Knoop et al, 2010). A full list of the modifications we made can be found in Supplemental Data S1.…”