Transcriptional response of Sacchromyces cerevisiae to change in oxygen provision
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ABSTRACT: In industrial fermentations of Saccharomyces cerevisiae, transient changes in oxygen concentration commonly occur and it is important to understand the behaviour of cells during these changes. Saccharomyces cerevisiae CEN.PK113-1A was grown in glucose-limited chemostat culture with 1.0% and 20.9% O2 in the inlet gas (D= 0.10 /h, pH5, 30C). After steady state was achieved, oxygen was replaced with nitrogen and cultures were followed until new steady state was achieved. The overall responses to anaerobic conditions of cells initially in different conditions were very similar. Independent of initial culture conditions, transient downregulation of genes related to growth and cell proliferation, mitochondrial translation and protein import, and sulphate assimilation was seen. In addition, transient or permanent upregulation of genes related to protein degradation, and phosphate and amino acid uptake was observed in all cultures. However, only in the initially oxygen-limited cultures was a transient upregulation of genes related to fatty acid oxidation, peroxisomal biogenesis, oxidative phosphorylation, TCA cycle, response to oxidative stress, and pentose phosphate pathway observed. Furthermore, from the initially oxygen-limited conditions, a rapid response around the metabolites of upper glycolysis and the pentose phosphate pathway was seen, while from the initially fully aerobic conditions, a slower response around the pathways for utilisation of respiratory carbon sources was observed. Time series analysis starting from two (1% and 20.9%) levels of oxygen provision. Seven timepoints from both time series and two biological replicates from each timepoint were analysed.
Project description:Saccharomyces cerevisiae CEN.PK113-1A was grown in glucose-limited chemostat culture with 0%, 0.5%, 1.0%, 2.8% or 20.9% O2 in the inlet gas (D= 0.10 /h, pH5, 30C). Experiment Overall Design: Four (0,0.5,2.8 and 20.9% oxygen) or seven samples (1% oxygen) were analysed. Samples were either from four (0,1,20.9% oxygen) or two independent cultivations (0.5, 2.8% oxygen). One sample (VTT_Ys23_13_1%) was found to be an outlier and was removed from the analysis.
Project description:In industrial fermentations of Saccharomyces cerevisiae, transient changes in oxygen concentration commonly occur and it is important to understand the behaviour of cells during these changes. Saccharomyces cerevisiae CEN.PK113-1A was grown in glucose-limited chemostat culture with 1.0% and 20.9% O2 in the inlet gas (D= 0.10 /h, pH5, 30C). After steady state was achieved, oxygen was replaced with nitrogen and cultures were followed until new steady state was achieved. The overall responses to anaerobic conditions of cells initially in different conditions were very similar. Independent of initial culture conditions, transient downregulation of genes related to growth and cell proliferation, mitochondrial translation and protein import, and sulphate assimilation was seen. In addition, transient or permanent upregulation of genes related to protein degradation, and phosphate and amino acid uptake was observed in all cultures. However, only in the initially oxygen-limited cultures was a transient upregulation of genes related to fatty acid oxidation, peroxisomal biogenesis, oxidative phosphorylation, TCA cycle, response to oxidative stress, and pentose phosphate pathway observed. Furthermore, from the initially oxygen-limited conditions, a rapid response around the metabolites of upper glycolysis and the pentose phosphate pathway was seen, while from the initially fully aerobic conditions, a slower response around the pathways for utilisation of respiratory carbon sources was observed.
Project description:In this study, we analyse a high 3HP producing strain of Saccharomyces cerevisiae through 13C metabolic flux and transcriptomic analyses. The engineered strain saw upregulation across glycolysis and the pentose phosphate pathway compared to the reference strain. Our analysis of the transcriptomic data produce a strategy that successfully increased 3HP titres.
Project description:We recentlly showed that everolimus, a mTORC1 inhibitor increases reactive oxygen species (ROS) levels, decreases the levels of NADPH and of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the pentose phosphate pathway (PPP), and induces apoptosis of T-ALL cells.
Project description:Ischemia exists in many diseased tissues including arthritic joints, atherosclerotic plaques and malignant tumors. Macrophages accumulate in these sites and upregulate genes in response to the hypoxia present. We used microarrays to detail the hypoxia upregulated gene in human primary macrophages. Experiment Overall Design: Primary macrophages were differentiated for 7 days in vitro from human peripheral blood (monocyte-derived macrophages, MDMs) and were subjected to severe hypoxia (< 0.5% O2) or normoxia (20.9% O2) in 5% CO2 humidified multi-gas incubators.
Project description:Previously isolated spontaneous mutants of Rhodobacter sphaeroides, which were initially compromised in their ability to assimilate carbon dioxide through the reductive pentose phosphate pathway, were found to exhibit abnormal nitrogenase gene regulation as well as altered patterns of nitrogenase enzymatic activity. The genomes of these strains were studied by whole genome pyrosequencing and whole genome microarray analysis to identify possible loci responsible for the observed phenotypes.
Project description:Previously isolated spontaneous mutants of Rhodobacter sphaeroides, which were initially compromised in their ability to assimilate carbon dioxide through the reductive pentose phosphate pathway, were found to exhibit abnormal nitrogenase gene regulation as well as altered patterns of nitrogenase enzymatic activity. The genomes of these strains were studied by whole genome pyrosequencing and whole genome microarray analysis to identify possible loci responsible for the observed phenotypes. 3 R.sphaeroides strains were grown in matching conditions to reveal strain-specific gene expression
Project description: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, EntnerM-bM-^@M-^SDoudoroff 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:The goal of the study is to use Next generation sequencing (RNA-seq) and 13C based flux analysis to study the underlying regulation of citric acid metabolism in mixed culture fermentation (glucose and glycerl) of Yarrowia lipolytica. We sequenced the RNA from 4 different samples in the mixed culture (glucose and glycerol) under oxygen excess and limited conditions with 2 replicates each . Transcriptional profiles showed that under oxygen limited conditions, due to deficient mitochondrial activity, citric acid is being consumed back after glycerol exhaustion eventhough glucose is present in excess. Transcriptome and fluxome profiles showed that glucose is mainly directed towards the Pentose phosphate pathway in the dual substrate fermentations.
Project description: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.