Gene expression-based investigation of a new role for the glyoxylate shunt in contributing to tolerance to oxidative stress.
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ABSTRACT:
ORGANISM(S): Pseudomonas aeruginosa PAO1
PROVIDER: GSE78230 | GEO | 2016/02/24
SECONDARY ACCESSION(S): PRJNA312967
REPOSITORIES: GEO
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Project description:Pseudomonas aeruginosa harbors sophisticated transcription factor (TF) networks to coordinately regulate cellular metabolic states for rapidly adapting to changing environments. The superior capacity in fine-tuning the metabolic states enables its success in tolerance to antibiotics and evading host immune defenses. However, the linkage among transcriptional regulation, metabolic states, and antibiotic tolerance in P. aeruginosa remains largely unclear. By screening the P. aeruginosa TF mutant library constructed by CRISPR/Cas12k-guided transposase, we identify that rccR (PA5438) is a major genetic determinant in aminoglycoside antibiotic tolerance, the deletion of which substantially enhances bacterial tolerance. We further reveal the inhibitory roles of RccR in pyruvate metabolism (aceE/F) and glyoxylate shunt pathway (aceA and glcB), and overexpression of aceA or glcB enhances bacterial tolerance. Moreover, we identify that 2-keto-3-deoxy-6-phosphogluconate (KDPG) is a signal molecule that directly binds to RccR. Structural analysis of the RccR/KDPG complex reveals the detailed interactions. Substitution of the key residues R152, K270, or R277 with alanine abolishes KDPG sensing by RccR and impairs bacterial growth with glycerol or glucose as the sole carbon source. Collectively, our study unveils the connection between aminoglycoside antibiotic tolerance and RccR-mediated central carbon metabolism regulation in P. aeruginosa, and elucidates the KDPG sensing mechanism by RccR.
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Project description:Trascriptome profiles in the cells of A. aceti wild-type strain and its isogenic aceA glcB mutant during growth in medium contaning ethanol and glucose was determined by NimbleGen Eukaryotic Expression array (4x72K).
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Project description:Obesity is becoming increasingly widespread in developed countries, and is often associated with heart diseases and diabetes. Elevated levels of plasma free fatty acids are a biochemical hallmark of obesity. Unlike plants and bacteria, mammals cannot utilize fatty acids to generate glucose because of the lack of glyoxylate shunt enzymes. Instead, fatty acids are used for energy storage, and their utilization is regulated at multiple levels ranging from hormonal to metabolic ensuring that glucose is preferentially oxidized before fatty acids. Here we designed a synthetic gene-metabolic circuit to alter the intracellular signaling and metabolic pathways that control fatty acid metabolism. By introducing the Escherichia coli glyoxylate shunt enzymes, isocitrate lyase (AceA) and malate synthase (AceB), into the mitochondria of human hepatocytes, we demonstrated that fatty acid utilization is preferentially increased while glucose uptake is significantly reduced. This bacterial pathway diverts signal metabolites (citrate, acetyl-CoA, and malonyl-CoA) that inhibits fatty acid uptake and provides an additional channel for fatty acid utilization. Remarkably, the hepatocytes readily adapted to the synthetic circuit by a series of global transcriptional and post-translational changes in metabolic and signal transduction pathways that further advanced our design objective. This systems approach illustrates the logic of the synergistic interaction between metabolism and signal transduction. The ready acceptance of this non-native pathway by hepatocytes suggests the plasticity of liver metabolism and opens a possibility for the synthetic approach in regulating human metabolism. Keywords: Fatty acid response, synthetic circuit, carbohydrate metabolism, stably transfected HepG2 cell line, glyoxylate shunt
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Project description:The glyoxylate shunt (GS) is a two-step metabolic pathway (isocitrate lyase, aceA; and malate synthase, glcB) that serves as an alternative to the tricarboxylic acid cycle. The GS bypasses the carbon dioxide-producing steps of the tricarboxylic acid cycle and is essential for acetate and fatty acid metabolism in bacteria. GS can be up-regulated under conditions of oxidative stress, antibiotic stress, and host infection, which implies that it plays important but poorly explored roles in stress defense and pathogenesis. In many bacterial species, including Pseudomonas aeruginosa, aceA and glcB are not in an operon, unlike in Escherichia coli In P. aeruginosa, we explored relationships between GS genes and growth, transcription profiles, and biofilm formation. Contrary to our expectations, deletion of aceA in P. aeruginosa improved cell growth under conditions of oxidative and antibiotic stress. Transcriptome data suggested that aceA mutants underwent a metabolic shift toward aerobic denitrification; this was supported by additional evidence, including up-regulation of denitrification-related genes, decreased oxygen consumption without lowering ATP yield, increased production of denitrification intermediates (NO and N2O), and increased cyanide resistance. The aceA mutants also produced a thicker exopolysaccharide layer; that is, a phenotype consistent with aerobic denitrification. A bioinformatic survey across known bacterial genomes showed that only microorganisms capable of aerobic metabolism possess the glyoxylate shunt. This trend is consistent with the hypothesis that the GS plays a previously unrecognized role in allowing bacteria to tolerate oxidative stress.
| S-EPMC4882458 | biostudies-literature
Project description:Obesity is becoming increasingly widespread in developed countries, and is often associated with heart diseases and diabetes. Elevated levels of plasma free fatty acids are a biochemical hallmark of obesity. Unlike plants and bacteria, mammals cannot utilize fatty acids to generate glucose because of the lack of glyoxylate shunt enzymes. Instead, fatty acids are used for energy storage, and their utilization is regulated at multiple levels ranging from hormonal to metabolic ensuring that glucose is preferentially oxidized before fatty acids. Here we designed a synthetic gene-metabolic circuit to alter the intracellular signaling and metabolic pathways that control fatty acid metabolism. By introducing the Escherichia coli glyoxylate shunt enzymes, isocitrate lyase (AceA) and malate synthase (AceB), into the mitochondria of human hepatocytes, we demonstrated that fatty acid utilization is preferentially increased while glucose uptake is significantly reduced. This bacterial pathway diverts signal metabolites (citrate, acetyl-CoA, and malonyl-CoA) that inhibits fatty acid uptake and provides an additional channel for fatty acid utilization. Remarkably, the hepatocytes readily adapted to the synthetic circuit by a series of global transcriptional and post-translational changes in metabolic and signal transduction pathways that further advanced our design objective. This systems approach illustrates the logic of the synergistic interaction between metabolism and signal transduction. The ready acceptance of this non-native pathway by hepatocytes suggests the plasticity of liver metabolism and opens a possibility for the synthetic approach in regulating human metabolism. Experiment Overall Design: Wild type (WT) human hepatocyte HepG2 and HepG2 cells stably transfected with pBudaceAB (designated ACE), a vector containing isocitrate lyase and malate synthase from E. coli, were analyzed after 24hour exposure to palmitate. Cells were seeded at 70% confluency in 10cm plates with DMEM growth media augmented with 300uM palmitate. After 24hours, total RNA was harvested and hybrized to Affymetrix HG_U133A 2.0 GeneChips. Data was processed using GCOS 1.2 software. Experiment Overall Design: 2 WT biological replicates and 2 ACE biological replicates were analyzed. Experiment Overall Design:
2009-06-24 | E-GEOD-5903 | biostudies-arrayexpress