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PloS One 2023Understanding metabolism in the pathogen Candida glabrata is key to identifying new targets for antifungals. The thiamine biosynthetic (THI) pathway is partially...
Understanding metabolism in the pathogen Candida glabrata is key to identifying new targets for antifungals. The thiamine biosynthetic (THI) pathway is partially defective in C. glabrata, but the transcription factor CgPdc2 upregulates some thiamine biosynthetic and transport genes. One of these genes encodes a recently evolved thiamine pyrophosphatase (CgPMU3) that is critical for accessing external thiamine. Here, we demonstrate that CgPdc2 primarily regulates THI genes. In Saccharomyces cerevisiae, Pdc2 regulates both THI and pyruvate decarboxylase (PDC) genes, with PDC proteins being a major thiamine sink. Deletion of PDC2 is lethal in S. cerevisiae in standard growth conditions, but not in C. glabrata. We uncover cryptic cis elements in C. glabrata PDC promoters that still allow for regulation by ScPdc2, even when that regulation is not apparent in C. glabrata. C. glabrata lacks Thi2, and it is likely that inclusion of Thi2 into transcriptional regulation in S. cerevisiae allows for a more complex regulation pattern and regulation of THI and PDC genes. We present evidence that Pdc2 functions independent of Thi2 and Thi3 in both species. The C-terminal activation domain of Pdc2 is intrinsically disordered and critical for species differences. Truncation of the disordered domains leads to a gradual loss of activity. Through a series of cross species complementation assays of transcription, we suggest that there are multiple Pdc2-containing complexes, and C. glabrata appears to have the simplest requirement set for THI genes, except for CgPMU3. CgPMU3 has different cis requirements, but still requires Pdc2 and Thi3 to be upregulated by thiamine starvation. We identify the minimal region sufficient for thiamine regulation in CgTHI20, CgPMU3, and ScPDC5 promoters. Defining the cis and trans requirements for THI promoters should lead to an understanding of how to interrupt their upregulation and provide targets in metabolism for antifungals.
Topics: Saccharomyces cerevisiae; Candida glabrata; Transcription Factors; Fungal Proteins; Pyruvate Decarboxylase; Thiamine; Carboxy-Lyases; Promoter Regions, Genetic; Intrinsically Disordered Proteins; Gene Expression Regulation, Fungal
PubMed: 37285346
DOI: 10.1371/journal.pone.0286744 -
Plants (Basel, Switzerland) Aug 2023Kiwifruit ( spp.) is susceptible to waterlogging stress. Although abundant wild germplasm resources exist among plants for improving the waterlogging tolerance of...
Kiwifruit ( spp.) is susceptible to waterlogging stress. Although abundant wild germplasm resources exist among plants for improving the waterlogging tolerance of kiwifruit cultivars, the underlying mechanisms remain largely unknown. Here, a comparative study was undertaken using one wild germplasm, Maorenshen ( Dunn, MRS), and one cultivar, Miliang-1 ( var. (A.Chev.) A.Chev. cv. Miliang-1, ML). Under stress, the ML plantlets were seriously damaged with wilted chlorotic leaves and blackened rotten roots, whereas the symptoms of injury in the MRS plantlets were much fewer, along with higher photosynthetic rates, chlorophyll fluorescence characteristics and root activity under stress conditions. However, neither aerenchyma in the root nor adventitious roots appeared in both germplasms upon stress exposure. The activities of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH), as well as their transcript levels, were constitutively higher in MRS than those in ML under both normal and stress conditions. Waterlogging stress significantly enhanced the PDC and ADH enzyme activities in both germplasms, which were 60.8% and 22.4% higher in the MRS roots than those in the ML roots under waterlogging stress, respectively. Moreover, MRS displayed higher activities of antioxidant enzymes, including SOD, CAT, and APX, as well as DPPH-radical scavenging ability, and decreased HO and MDA accumulation under both normal and stress conditions. Our findings suggest that the waterlogging tolerance of the wild germplasm was associated with high PDC and ADH, as well as antioxidant ability.
PubMed: 37571025
DOI: 10.3390/plants12152872 -
Microbial Cell Factories Jul 2023L-arginine is an important amino acid with applications in diverse industrial and pharmaceutical fields. N-acetylglutamate, synthesized from L-glutamate and acetyl-CoA,...
BACKGROUND
L-arginine is an important amino acid with applications in diverse industrial and pharmaceutical fields. N-acetylglutamate, synthesized from L-glutamate and acetyl-CoA, is a precursor of the L-arginine biosynthetic branch in microorganisms. The enzyme that produces N-acetylglutamate, N-acetylglutamate synthase, is allosterically inhibited by L-arginine. L-glutamate, as a central metabolite, provides carbon backbone for diverse biological compounds besides L-arginine. When glucose is the sole carbon source, the theoretical maximum carbon yield towards L-arginine is 96.7%, but the experimental highest yield was 51%. The gap of L-arginine yield indicates the regulation complexity of carbon flux and energy during the L-arginine biosynthesis. Besides endogenous biosynthesis, N-acetylglutamate, the key precursor of L-arginine, can be obtained by chemical acylation of L-glutamate with a high yield of 98%. To achieve high-yield production of L-arginine, we demonstrated a novel approach by directly feeding precursor N-acetylglutamate to engineered Escherichia coli.
RESULTS
We reported a new approach for the high yield of L-arginine production in E. coli. Gene argA encoding N-acetylglutamate synthase was deleted to disable endogenous biosynthesis of N-acetylglutamate. The feasibility of external N-acetylglutamate towards L-arginine was verified via growth assay in argA strain. To improve L-arginine production, astA encoding arginine N-succinyltransferase, speF encoding ornithine decarboxylase, speB encoding agmatinase, and argR encoding an arginine responsive repressor protein were disrupted. Based on overexpression of argDGI, argCBH operons, encoding enzymes of the L-arginine biosynthetic pathway, ~ 4 g/L L-arginine was produced in shake flask fermentation, resulting in a yield of 0.99 mol L-arginine/mol N-acetylglutamate. This strain was further engineered for the co-production of L-arginine and pyruvate by removing genes adhE, ldhA, poxB, pflB, and aceE, encoding enzymes involved in the conversion and degradation of pyruvate. The resulting strain was shown to produce 4 g/L L-arginine and 11.3 g/L pyruvate in shake flask fermentation.
CONCLUSIONS
Here, we developed a novel approach to avoid the strict regulation of L-arginine on ArgA and overcome the metabolism complexity in the L-arginine biosynthesis pathway. We achieve a high yield of L-arginine production from N-acetylglutamate in E. coli. Co-production pyruvate and L-arginine was used as an example to increase the utilization of input carbon sources.
Topics: Escherichia coli; Amino-Acid N-Acetyltransferase; Glutamic Acid; Arginine; Pyruvates; Carbon; Metabolic Engineering
PubMed: 37495979
DOI: 10.1186/s12934-023-02145-8 -
The Journal of Clinical Investigation Apr 2024Carbohydrates and lipids provide the majority of substrates to fuel mitochondrial oxidative phosphorylation (OXPHOS). Metabolic inflexibility, defined as an impaired...
Carbohydrates and lipids provide the majority of substrates to fuel mitochondrial oxidative phosphorylation (OXPHOS). Metabolic inflexibility, defined as an impaired ability to switch between these fuels, is implicated in a number of metabolic diseases. Here we explore the mechanism by which physical inactivity promotes metabolic inflexibility in skeletal muscle. We developed a mouse model of sedentariness, small mouse cage (SMC) that, unlike other classic models of disuse in mice, faithfully recapitulated metabolic responses that occur in humans. Bioenergetic phenotyping of skeletal muscle mitochondria displayed metabolic inflexibility induced by physical inactivity, demonstrated by a reduction in pyruvate-stimulated respiration (JO2) in absence of a change in palmitate-stimulated JO2. Pyruvate resistance in these mitochondria was likely driven by a decrease in phosphatidylethanolamine (PE) abundance in the mitochondrial membrane. Reduction in mitochondrial PE by heterozygous deletion of phosphatidylserine decarboxylase (PSD) was sufficient to induce metabolic inflexibility measured at the whole-body level, as well as at the level of skeletal muscle mitochondria. Low mitochondrial PE in C2C12 myotubes was sufficient to increase glucose flux towards lactate. We further implicate that resistance to pyruvate metabolism is due to attenuated mitochondrial entry via mitochondrial pyruvate carrier (MPC). These findings suggest a mechanism by which mitochondrial PE directly regulates MPC activity to modulate metabolic flexibility in mice.
PubMed: 38652544
DOI: 10.1172/JCI167371 -
BMC Plant Biology Jun 2023Flooding is among the most severe abiotic stresses in plant growth and development. The mechanism of submergence tolerance of cotton in response to submergence stress is...
BACKGROUND
Flooding is among the most severe abiotic stresses in plant growth and development. The mechanism of submergence tolerance of cotton in response to submergence stress is unknown.
RESULTS
The transcriptome results showed that a total of 6,893 differentially expressed genes (DEGs) were discovered under submergence stress. Gene Ontology (GO) enrichment analysis showed that DEGs were involved in various stress or stimulus responses. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that DEGs related to plant hormone signal transduction, starch and sucrose metabolism, glycolysis and the biosynthesis of secondary metabolites were regulated by submergence stress. Eight DEGs related to ethylene signaling and 3 ethylene synthesis genes were identified in the hormone signal transduction. For respiratory metabolism, alcohol dehydrogenase (ADH, GH_A02G0728) and pyruvate decarboxylase (PDC, GH_D09G1778) were significantly upregulated but 6-phosphofructokinase (PFK, GH_D05G0280), phosphoglycerate kinase (PGK, GH_A01G0945 and GH_D01G0967) and sucrose synthase genes (SUS, GH_A06G0873 and GH_D06G0851) were significantly downregulated in the submergence treatment. Terpene biosynthetic pathway-related genes in the secondary metabolites were regulated in submergence stress.
CONCLUSIONS
Regulation of terpene biosynthesis by respiratory metabolism may play a role in enhancing the tolerance of cotton to submergence under flooding. Our findings showed that the mevalonate pathway, which occurs in the cytoplasm of the terpenoid backbone biosynthesis pathway (ko00900), may be the main response to submergence stress.
Topics: Gene Expression Profiling; Transcriptome; Carbohydrate Metabolism; Stress, Physiological; Ethylenes; Gene Expression Regulation, Plant
PubMed: 37344795
DOI: 10.1186/s12870-023-04334-4 -
Polish Journal of Microbiology Mar 2024Hydrocarbon constituents of petroleum are persistent, bioaccumulated, and bio-magnified in living tissues, transported to longer distances, and exert hazardous effects...
Hydrocarbon constituents of petroleum are persistent, bioaccumulated, and bio-magnified in living tissues, transported to longer distances, and exert hazardous effects on human health and the ecosystem. Bioaugmentation with microorganisms like bacteria is an emerging approach that can mitigate the toxins from environmental sources. The present study was initiated to target the petroleum-contaminated soil of gasoline stations situated in Lahore. Petroleum degrading bacteria were isolated by serial dilution method followed by growth analysis, biochemical and molecular characterization, removal efficiency estimation, metabolites extraction, and GC-MS of the metabolites. Molecular analysis identified the bacterium as Bacillus cereus, which exhibited maximum growth at 72 hours and removed 75% petroleum. Biochemical characterization via the Remel RapID ONE panel system showed positive results for arginine dehydrolase (ADH), ornithine decarboxylase (ODC), lysine decarboxylase (LDC), -nitrophenyl-β-D-galactosidase (ONPG), -nitrophenyl-β-D-glucosidase (βGLU), -nitrophenyl-N-acetyl-β-D-glucosaminidase (NAG), malonate (MAL), adonitol fermentation (ADON), and tryptophane utilization (IND). GC-MS-based metabolic profiling identified alcohols (methyl alcohol, -, - and -cresols, catechol, and 3-methyl catechol), aldehydes (methanone, acetaldehyde, and -tolualdehyde), carboxylic acid (methanoic acid, -muconic acid, cyclohexane carboxylic acid and benzoic acid), conjugate bases of carboxylic acids (benzoate, -muconate, 4-hydroxybenzoate, and pyruvate) and cycloalkane (cyclohexene). It suggested the presence of methane, methylcyclohexane, toluene, xylene, and benzene degradation pathways in .
Topics: Humans; Bacillus cereus; Ecosystem; Hydrocarbons; Methane; Carboxylic Acids
PubMed: 38437466
DOI: 10.33073/pjm-2024-012 -
Biology Feb 2024Ammonium (NH) toxicity is ubiquitous in plants. To investigate the underlying mechanisms of this toxicity and bicarbonate (HCO)-dependent alleviation, wheat plants were...
Ammonium (NH) toxicity is ubiquitous in plants. To investigate the underlying mechanisms of this toxicity and bicarbonate (HCO)-dependent alleviation, wheat plants were hydroponically cultivated in half-strength Hoagland nutrient solution containing 7.5 mM NO (CK), 7.5 mM NH (SA), or 7.5 mM NH + 3 mM HCO (AC). Transcriptomic analysis revealed that compared to CK, SA treatment at 48 h significantly upregulated the expression of genes encoding fermentation enzymes (pyruvate decarboxylase (PDC), alcohol dehydrogenase (ADH), and lactate dehydrogenase (LDH)) and oxygen consumption enzymes (respiratory burst oxidase homologs, dioxygenases, and alternative oxidases), downregulated the expression of genes encoding oxygen transporters (PIP-type aquaporins, non-symbiotic hemoglobins), and those involved in energy metabolism, including tricarboxylic acid (TCA) cycle enzymes and ATP synthases, but upregulated the glycolytic enzymes in the roots and downregulated the expression of genes involved in the cell cycle and elongation. The physiological assay showed that SA treatment significantly increased PDC, ADH, and LDH activity by 36.69%, 43.66%, and 61.60%, respectively; root ethanol concentration by 62.95%; and lactate efflux by 23.20%, and significantly decreased the concentrations of pyruvate and most TCA cycle intermediates, the complex V activity, ATP content, and ATP/ADP ratio. As a consequence, SA significantly inhibited root growth. AC treatment reversed the changes caused by SA and alleviated the inhibition of root growth. In conclusion, NH treatment alone may cause hypoxic stress in the roots, inhibit energy generation, suppress cell division and elongation, and ultimately inhibit root growth, and adding HCO remarkably alleviates the NH-induced inhibitory effects on root growth largely by attenuating the hypoxic stress.
PubMed: 38392319
DOI: 10.3390/biology13020101 -
Journal of Fungi (Basel, Switzerland) Sep 2023Phenylacetylcarbinol (PAC) is a precursor for the synthesis of several pharmaceuticals, including ephedrine, pseudoephedrine, and norephedrine. PAC is commonly produced...
Phenylacetylcarbinol (PAC) is a precursor for the synthesis of several pharmaceuticals, including ephedrine, pseudoephedrine, and norephedrine. PAC is commonly produced through biotransformation using microbial pyruvate decarboxylase (PDC) in the form of frozen-thawed whole cells. However, the lack of microorganisms capable of high PDC activity is the main factor in the production of PAC. In addition, researchers are also looking for ways to utilize agro-industrial residues as an inexpensive carbon source through an integrated biorefinery approach in which sugars can be utilized for bioethanol production and frozen-thawed whole cells for PAC synthesis. In the present study, , , and the co-culture of both strains were compared for their biomass and ethanol concentrations, as well as for their volumetric and specific PDC activities when cultivated in a sugarcane bagasse (SCB) hydrolysate medium (SCBHM). The co-culture that resulted in a higher level of PAC (8.65 ± 0.08 mM) with 26.4 ± 0.9 g L ethanol production was chosen for further experiments. Biomass production was scaled up to 100 L and the kinetic parameters were studied. The biomass harvested from the bioreactor was utilized as frozen-thawed whole cells for the selection of an initial pyruvate (Pyr)-to-benzaldehyde (Bz) concentration ([Pyr]/[Bz]) ratio suitable for the PAC biotransformation in a single-phase emulsion system. The initial [Pyr]/[Bz] at 100/120 mM resulted in higher PAC levels with 10.5 ± 0.2 mM when compared to 200/240 mM (8.60 ± 0.01 mM). A subsequent two-phase emulsion system with Pyr in the aqueous phase, Bz in the organic phase, and frozen-thawed whole cells of the co-culture as the biocatalyst produced a 1.46-fold higher PAC level when compared to a single-phase emulsion system. In addition, the cost analysis strategy indicated preliminary costs of USD 0.82 and 1.01/kg PAC for the single-phase and two-phase emulsion systems, respectively. The results of the present study suggested that the co-culture of and can effectively produce bioethanol and PAC from SCB and would decrease the overall production cost on an industrial scale utilizing the two-phase emulsion system with the proposed multiple-pass strategy.
PubMed: 37755036
DOI: 10.3390/jof9090928 -
International Journal of Molecular... Dec 2023A cell population characterized by the release of glucose repression and known as [] emerges spontaneously in the yeast . This study revealed that the [] variants...
A cell population characterized by the release of glucose repression and known as [] emerges spontaneously in the yeast . This study revealed that the [] variants exhibit retarded alcoholic fermentation when glucose is the sole carbon source. To identify the key to the altered glucose response, the gene expression profile of [] cells was examined. Based on RNA-seq data, the [] status was linked to impaired function of the Cyc8p-Tup1p complex. Loss of Cyc8p led to a decrease in the initial rate of alcoholic fermentation under glucose-rich conditions via the inactivation of pyruvate decarboxylase, an enzyme unique to alcoholic fermentation. These results suggest that Cyc8p can become inactive to attenuate alcoholic fermentation. These findings may contribute to the elucidation of the mechanism of non-genetic heterogeneity in yeast alcoholic fermentation.
Topics: Carbon; Fermentation; Glucose; Pyruvate Decarboxylase; Saccharomyces cerevisiae
PubMed: 38203474
DOI: 10.3390/ijms25010304 -
Microbial Cell Factories May 2024Zymomonas mobilis is well known for its outstanding ability to produce ethanol with both high specific productivity and with high yield close to the theoretical maximum....
BACKGROUND
Zymomonas mobilis is well known for its outstanding ability to produce ethanol with both high specific productivity and with high yield close to the theoretical maximum. The key enzyme in the ethanol production pathway is the pyruvate decarboxylase (PDC) which is converting pyruvate to acetaldehyde. Since it is widely considered that its gene pdc is essential, metabolic engineering strategies aiming to produce other compounds derived from pyruvate need to find ways to reduce PDC activity.
RESULTS
Here, we present a new platform strain (sGB027) of Z. mobilis in which the native promoter of pdc was replaced with the IPTG-inducible P allowing for a controllable expression of pdc. Expression of lactate dehydrogenase from E. coli in sGB027 allowed the production of D-lactate with, to the best of our knowledge, the highest reported specific productivity of any microbial lactate producer as well as with the highest reported lactate yield for Z. mobilis so far. Additionally, by expressing the L-alanine dehydrogenase of Geobacillus stearothermophilus in sGB027 we produced L-alanine, further demonstrating the potential of sGB027 as a base for the production of compounds other than ethanol.
CONCLUSION
We demonstrated that our new platform strain can be an excellent starting point for the efficient production of various compounds derived from pyruvate with Z. mobilis and can thus enhance the establishment of this organism as a workhorse for biotechnological production processes.
Topics: Zymomonas; Pyruvate Decarboxylase; Metabolic Engineering; Ethanol; Lactic Acid; Escherichia coli; L-Lactate Dehydrogenase; Alanine; Pyruvic Acid; Fermentation
PubMed: 38773442
DOI: 10.1186/s12934-024-02419-9