The sRNA SorY confers resistance during photooxidative stress by affecting a metabolite transporter in Rhodobacter sphaeroides
ABSTRACT: Exposure to oxygen and light generates photooxidative stress by the bacteriochlorophyll a mediated formation of singlet oxygen (1O2) in the facultative photosynthetic bacterium Rhodobacter sphaeroides. We have identified SorY as an sRNA, which is induced under several stress conditions and confers increased resistance against 1O2. SorY by direct interaction decreases the levels of takP mRNA, encoding a TRAP-T transporter. A takP mutant shows higher resistance to 1O2 than the wild type, which is no longer affected by SorY. We present a model in which SorY reduces the metabolite flux into the TCA cycle by reducing malate import through TakP. It was previously shown that oxidative stress in bacteria leads to switch from glycolysis to the pentose phosphate cycle and to reduced activity of the tricaboxylic acid cycle. As a consequence the production of the prooxidant NADH is reduced and production of the protective NADPH is enhanced. In R. sphaeroides enzymes for glycolysis, pentose phosphate pathway, Entner–Doudoroff pathway and gluconeogenesis are induced in response to 1O2 by the alternative sigma factor RpoHII. The same is true for the sRNA SorY. By limiting malate import SorY thus contributes to the balance of the metabolic fluxes under photooxidative stress conditions. This assigns a so far unknown function to an sRNA in oxidative stress response. RNA samples collected from a control strain harbouring an empty vector (2.4.1pBBR) and of the SorY overexpressing strain (2.4.1pBBRSorYi) after 10 min of 1O2 stress were analyzed by two-color microarrays
Project description:Transcriptional profiling of R. sphaeroides delta-cryB compared to control R. sphaeroides 2.4.1 under photo-oxidative stress, aerobic conditions. Two-strain experiment under 20' photo-oxidative stress (singlet oxygen generated by methylene blue under high light illumination) and aerobic (180 µM) conditions
Project description:To gain a better understanding of the transcription factors that regulate central carbon metabolism in Rhodobacter sphaeroides global gene expression analysis was used to determine genes under the regulatory influence of 2 transcription factors: CcmR (RSP_1663) and AkgR (RSP_0981) both predicted to be involved in the regulation of central carbon and energy metabolism. Microarray analysis conducted for deletion strains of 2 transcription factors known or predicted to be involved in the regulation of central carbon metabolism in Rhodobacter sphaeroides using the R. sphaeroides Affymetrix gene chip. These deletion mutant expression profiles were compared to that of wild type cells to determine differentially expressed genes regulated by these transcription factors.
Project description:Rhodobacter sphaeroides is the best studied photosynthetic bacterium, yet much remains unknown about its transcriptional regulatory processes on a genome-scale. We developed a work-flow for genome-scale reconstruction of transcriptional regulatory networks and applied it to sequence and gene expression data sets available for R. sphaeroides. To assess the predictive performance of our reconstructed model, we generated global transcript level and/or protein-DNA interaction data for 3 transcription factors (PpsR, RSP_0489 and RSP_3341). This dataset contains global transcript level analyses for RSP_0489 and RSP_3341 deletion strains, as well as matching wild type controls. Microarray analysis conducted for deletion strains of 2 previously uncharacterized transcription factors predicted to be involved in the regulation of carbon metabolism and iron homeostasis in R. sphaeroides using the R. sphaeroides Affymetrix gene chip. These deletion mutant expression profiles were compared to that of wild type cells to determine differentially expressed genes regulated by these transcription factors.
Project description:To further characterize the capability of R. sphaeroides to cope with high cobalt ion concentrations, we combined the selection of adaptive defective mutants, carried out by negative selection of transposon insertional libraries on 5 mM Co2+ enriched solid medium, with the analysis of growing capacities and transcriptome profiling of a selected mutant (R95).
Project description:This SuperSeries is composed of the following subset Series: GSE39711: RpoHI and RpoHII regulons in Rhodobacter sphaeroides 2.4.1 from chromatin immuno-precipitation GSE39712: RpoHI and RpoHII regulons in Rhodobacter sphaeroides 2.4.1 from gene expression profiling Refer to individual Series
Project description:Transcriptional and translational profiling of R. sphaeroides WT 2.4.1 under singlet oxygen stress compared to control (no stress) conditions RNA samples collected at time-point zero and at different time-points after singlet oxygen stress were analyzed by two-color microarrays
Project description:This SuperSeries is composed of the following subset Series: GSE33553: R. sphaeroides delta-cryB vs. R. sphaeroides 2.4.1 photo-oxidative stress, aerobic conditions GSE33554: R. sphaeroides delta-CryB vs. R. sphaeroides 2.4.1 microarobic conditions GSE33555: R. sphaeroides delta-cryB vs. R. sphaeroides 2.4.1 under blue light, semiaerobic conditions Refer to individual Series
Project description:The facultatively photosynthetic bacterium Rhodobacter sphaeroides harbors an unusual LOV (light, oxygen, voltage) domain protein, RsLOV. While showing a characteristic photocycle, the protein misses a C - terminal output domain, similar to PpSB2 in Pseudomonas putida. Oxygen tension and light quantity are the two main responsible factors controlling the expression of photosynthesis genes in Rhodobacter sphaeroides. Two photoreceptor proteins are known to be involved in this regulation: the intensively studied AppA protein and the more recently identified cryptochrome-like protein CryB. Here we show by transcriptome and physiological studies that RsLOV is also involved in the regulation of photosynthetic gene expression. Our data further hint to a connection between RsLOV and the carbon hydrate metabolism, chemotaxis, as well as to the cellular response to photooxidative stress. RsLOV does not only affect blue light dependent gene expression but also redox-dependent regulation. This SuperSeries is composed of the following subset Series: GSE33194: R. sphaeroides Δlov vs. R. sphaeroides 2.4.1 (microarobic conditions) GSE33259: R. sphaeroides Δlov vs. R. sphaeroides 2.4.1 (blue light, semiaerobic conditions) GSE33260: R. sphaeroides Δlov vs. R. sphaeroides 2.4.1 (singlet oxygen stress, aerobic conditions)
Project description:Transcriptional profiling of R. sphaeroides Δlov compared to control R. sphaeroides 2.4.1 under singlet oxygen stress, aerobic conditions Two-strain experiment with overnight cultures of the wild type 2.4.1 and the Δlov mutant. Both were diluted to an OD660 of 0.2 and gassed to adjust aerobic conditions (≈ 170 µM O2). 0.2 µM of methylene blue was added to the cultures to act as photosensitizer. After one doubling time of growth in the darkness cells were illuminated with 800 W m-2 of white light for 7 min.
Project description:This SuperSeries is composed of the following subset Series: GSE33533: R. sphaeroides Δirr -Fe vs. R. sphaeroides Δirr +Fe under microaerobic conditions GSE33534: R. sphaeroides Δirr vs. R. sphaeroides 2.4.1 under microaerobic conditions Refer to individual Series