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With the wide application of stable isotope tracer metabolomics technology, its comprehensive analysis and in-depth mining of data are particularly important, and metabolic flux analysis is one of the main technical means, especially in the study of glucose metabolism. Metabolic flux analysis technology combines isotope tracing with mathematical models to deduce and calculate the metabolic flux between metabolites. The metabolic flux provides more information for research and reflects a dynamic metabolic process more clearly and specifically. This paper reviews the basic process, precautions, and application examples of metabolic flux analysis in glucose metabolism research, and provides a reference for the application of metabolic flux analysis based on stable isotope tracer metabolomics in glucose metabolism research.
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Metabolic reprogramming is a hallmark of tumors. Tumors own unique metabolic patterns in different stages of their occurrence and development. The stable isotope metabolic flux analysis technology uses stable isotope to trace the metabolites in tumors and crystallize tumor metabolism network. Stable isotope metabolic flux analysis is a useful tool for studying tumor metabolism, which can determine the nutritional sources, find the metabolic liabilities, confirm the metabolic pattern of tumors, and discover new mechanisms of tumor metabolic reprogramming, thus providing theoretical bases for imaging, diagnosis, treatment and evaluation of tumor. This article reviews the applications of stable isotope flux analysis in tumor metabolic reprogramming.
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In this study, voltage was used as a disturbance factor to investigate the relationship between microbial community and methane (CH4) production flux in a microbial electrolytic cell coupled anaerobic digestion (MEC-AD). Metabolic flux analysis (MFA) was used to explore the relationship between the CH4 metabolic flux produced and the microbes. The results showed that both methane production flux and hydrogen production flux changed significantly upon voltage disturbance, while the voltage disturbance had little effect on acetic acid production flux. The maximum CH4 production flux under 0.6 V disturbance was 0.522±0.051, which increased by 77% and 32%, respectively, compared with that of the control group under 1.0 V (0.295±0.013) and under 1.4 V (0.395±0.029). In addition, an average of 15.7%±2.9% of H2 (flux) was used to reduce CO2 to produce CH4 and acetic acid, and an average of 27.7%±6.9% of acetic acid (flux) was converted to CH4. Moreover, the abundance of Lachnospiraceae significantly affected the flux of acetic acid. The flux of CH4 production is positively correlated with the abundances of Petrimonas, Syntrophomonas, Blvii28, and Acinetobacter, and negatively correlated with the abundances of Tuzzerella and Sphaerochaeta. The species that affected the flux of H2 and CH4 were similar, mostly belonging to Bacteroides, Clostridium, Pseudomonas and Firmicutes. Furthermore, the interspecies interaction is also an important factor affecting the MEC-AD methanogenesis flux.
Subject(s)
Acetates , Anaerobiosis , Bioreactors , Electrolysis , MethaneABSTRACT
There is an urgent need to elucidate the pathogenesis of myocardial ischemia (MI) and potential drug treatments.Here,the anti-MI mechanism and material basis of Ginkgo biloba L.extract (GBE) were studied from the perspective of energy metabolism flux regulation.Metabolic flux analysis (MFA) was performed to investigate energy metabolism flux disorder and the regulatory nodes of GBE components in isoproterenol (ISO)-induced ischemia-like cardiomyocytes.It showed that[U-13C]glucose derived m+2 isotopologues from the upstream tricarboxylic acid (TCA) cycle metabolites were markedly accu-mulated in ISO-injured cardiomyocytes,but the opposite was seen for the downstream metabolites,while their total cellular concentrations were increased.This indicates a blockage of carbon flow from glycolysis and enhanced anaplerosis from other carbon sources.A Seahorse test was used to screen for GBE components with regulatory effects on mitochondrial aerobic respiratory dysfunction.It showed that bilobalide protected against impaired mitochondrial aerobic respiration.MFA also showed that bilobalide significantly modulated the TCA cycle flux,reduced abnormal metabolite accumulation,and balanced the demand of different carbon sources.Western blotting and PCR analysis showed that bilobalide decreased the enhanced expression of key metabolic enzymes in injured cells.Bilobalide's efficacy was verified by in vivo experiments in rats.This is the first report to show that bilobalide,the active ingredient of GBE,protects against MI by rescuing impaired TCA cycle flux.This provides a new mechanism and potential drug treatment for MI.It also shows the potential of MFA/Seahorse combi-nation as a powerful strategy for pharmacological research on herbal medicine.
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With the rapid development of high sensitivity detection techniques such as nuclear magnetic resonance and mass spectrometry, stable isotope-resolved metabolomics has been widely used in elucidating the regulatory mechanism of metabolic pathways and metabolic flow analysis, and some breakthroughs have been made. In this paper the application of stable isotope-resolved metabolomics in glucose catabolic regulation, metabolic flow analysis and functional interpretation of key metabolic pathways is reviewed, providing references for the wider use and application of this technology.
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Studies have found that metformin is not only the preferred drug for lowering blood sugar, but also shows lipid-lowering and weight-loss effects. The purpose of this study was to use a hyperlipidemia hamster model to investigate the lipid-lowering effect of metformin and its effect on important metabolic pathways in lipid metabolism disorders. Fifty golden hamsters were divided into a control group, a model group, metformin high- and low-dose groups, and a simvastatin group. A high-fat diet was fed for 1 week to create the model, and then drug was administered for 11 weeks with the high-fat diet. Serum was taken for measurement of blood lipid and blood glucose at 2, 6, and 9 weeks after administration, and at weeks 3, 5, and 9 feces and urine were collected for 1H NMR metabolomics tests. After 11 weeks of intravenous injection of [U-13C6] glucose, serum was collected for a 13C NMR metabolic flux test. The results showed that the administration of metformin can significantly reduce blood lipids and glucose levels and can significantly affect metabolic pathways such as sugar metabolism, lipid metabolism, ketone metabolism, amino acid metabolism, and intestinal flora metabolism. The results of the metabolic flux analysis showed that the high-fat diet reduced the metabolism of tricarboxylic acids by 37.48%. After administration of low and high doses of metformin the metabolism of tricarboxylic acid increased by 98.14% and 143.10%, respectively. After administration of simvastatin tricarboxylic acid metabolism increased by 33.18%. The results indicate that metformin has a significant effect on promoting energy metabolism. This study used a combination of metabolomics and metabolic flow to explore the effect of metformin on lipid metabolism disorders and quantifies changes in the key pathway of energy metabolism-the tricarboxylic acid cycle. This study provides useful information for the study of the efficacy and mechanism of metformin, as well as a practical technical method for the screening of lipid-lowering drugs based on a hamster model.
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¹³C metabolic flux analysis (¹³C-MFA) enables the precise quantification of intracellular metabolic reaction rates by analyzing the distribution of mass isotopomers of proteinogenic amino acids or intracellular metabolites through ¹³C labeling experiments. ¹³C-MFA has received much attention as it can help systematically understand cellular metabolic characteristics, guide metabolic engineering design and gain mechanistic insights into pathophysiology. This article reviews the advances of ¹³C-MFA in the past 30 years and discusses its potential and future perspective, with a focus on its application in industrial biotechnology and biomedicine.
Subject(s)
Amino Acids , Carbon Isotopes , Isotope Labeling , Metabolic Engineering , Metabolic Flux Analysis , Models, BiologicalABSTRACT
In order to achieve rapid proliferation and adapt to the complex microenvironment, tumor cells have dominant characteristics such as unique metabolic patterns and the ability to escape from immunoregulation. Tumor cells reprogram multiple metabolic pathways to promote immune escape, which impacts tumor diagnosis, treatment and prognosis. Based on the effect of metabolic changes on tumor immune escape and its molecular mechanism, metabolic regulation provides new approaches to enhance immunotherapy. We review recent advances in tumor immuno-escape and immunotherapy based on metabolic regulation. Cutting-edge analytical techniques and methods for tumor metabolism research such as metabolomics, mass spectrometry imaging-based spatially-resolved metabolomics and metabolic flow analysis are also discussed.
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Shikimic acid is an intermediate metabolite in the synthesis of aromatic amino acids in Escherichia coli and a synthetic precursor of Tamiflu. The biosynthesis of shikimic acid requires blocking the downstream shikimic acid consuming pathway that leads to inefficient production and cell growth inhibition. In this study, a dynamic molecular switch was constructed by using growth phase-dependent promoters and degrons. This dynamic molecular switch was used to uncouple cell growth from shikimic acid synthesis, resulting in the production of 14.33 g/L shikimic acid after 72 h fermentation. These results show that the dynamic molecular switch could redirect the carbon flux by regulating the abundance of target enzymes, for better production.
Subject(s)
Escherichia coli/genetics , Escherichia coli Proteins/genetics , Industrial Microbiology/methods , Metabolic Engineering , Shikimic Acid/metabolismABSTRACT
With the rapid development of high-sensitivity detection methods, stable isotope tracing technique has received increasing attention. Stable isotope tracing technique can accurately track the activity of labeled compounds in the body through the tracer atoms and determine their specific metabolic pathways based on the distribution of isotopic peaks of the intermediate metabolites. By calculating the flux, the metabolic pathways are analyzed to provide a basis for the study of disease mechanism and drug metabolism. In recent years, the technique has a wide application in the field of biomedicine. This paper summarizes the applications of stable isotopic tracer technique in the metabolic regulation of endogenous substances such as carbohydrate metabolism, lipid metabolism, amino acid metabolism, hormone metabolism, nucleic acid metabolism, and so on.
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Background: Brettanomyces bruxellensis is an important spoilage yeast in the winemaking process. The capacity of this yeast to generate an undesired off-flavor constitutes a significant loss in the Chilean wine industry. Results: The proteomic profile of B. bruxellensis in the presence of p-coumaric acid was determined by 2D gel electrophoresis, gel image analysis and differential spot selection. A set of 41 proteins showed a differential accumulation of ±2 and a p-value <0.0001. The homology sequence analysis was performed using the databases available. Differential proteins belonged to the categories of 'energy production and conversion' and 'amino acid transport and metabolism'. Conclusions: The proteomic profile of B. bruxellensis cultivated in the presence of p-coumaric acid in synthetic wine, agrees with the hypothesis of metabolic flux regulation, allowing a better conditioning to an adverse environment. This study involved the translational level of B. bruxellensis in the production of ethylphenols and corroborated that this yeast presented an advantage in these stress conditions. Thus, this work will allow an understanding of the regulation and processes involved in the production of ethyl-derivate compounds by B. bruxellensis. Furthermore, it allows the development of newer and better techniques for spoilage yeast control.
Subject(s)
Wine , Coumaric Acids/metabolism , Proteome , Brettanomyces/metabolism , Phenols , Yeasts , Electrophoresis, Gel, Two-Dimensional , Electrophoresis , Wine IndustryABSTRACT
The central carbon metabolic system is the upstream energy source for microbial fermentation. In addition, it is a master switch for increasing the production of metabolites and an important part of the microbial metabolic network. Investigation into the relationship between genes, environmental factors, and metabolic networks is a main focus of systems biology, which significantly impacts research in biochemistry, metabolic engineering, and synthetic biology. To this end, the central carbon metabolic flux under a variety of growth conditions or using strains with various genetic modifications was previously measured in Saccharomyces cerevisiae using 13C tracer technology. However, the measured values were not integrated and investigated further. In this study, we collected and analyzed the metabolic flux rates of the central carbon metabolic system in S. cerevisiae measured in recent studies. We carried out preliminary analyses of flux values of each pathway, performed regression analyses on relationship between different fluxes, and extracted principal component factors of the flux variables. Based on the results, the general characteristics of pathway flux distribution were clustered and explored, and the effects of environmental and genetic factors on the flux distribution were analyzed. Furthermore, this study explored the relationship between similarity in the enzyme's transcriptional regulation and the correlations in the enzyme's reaction flux. Our results provide a foundation for further studies on the control of the central carbon metabolic flux and facilitate the search for targets in metabolic engineering research.
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Chloroplasts offer high-level transgene expression and transgene containment due to maternal inheritance, and are ideal hosts for biopharmaceutical biosynthesis via multigene engineering. To exploit these advantages, we have expressed 12 enzymes in chloroplasts for the biosynthesis of artemisinic acid (precursor of artemisinin, antimalarial drug) in an alternative plant system. Integration of transgenes into the tobacco chloroplast genome via homologous recombination was confirmed by molecular analysis, and biosynthesis of artemisinic acid in plant leaf tissues was detected with the help of 13C NMR and ESI-mass spectrometry. The excess metabolic flux of isopentenyl pyrophosphate generated by an engineered mevalonate pathway was diverted for the biosynthesis of artemisinic acid. However, expression of megatransgenes impacted the growth of the transplastomic plantlets. By combining two exogenous pathways, artemisinic acid was produced in transplastomic plants, which can be improved further using better metabolic engineering strategies for commercially viable yield of desirable isoprenoid products.
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In anaerobic bottles fermentation,glucose,fructose,xylose,lactose,maltose,sucrose and sugar alcohols could be used to produce succinic acid with Actinobacillus succinogenes. When sorbitol was utilized as the carbon source in the batch fermentation,more succinate and ethanol were produced compared with those using glucose,while producing less acetate and formate. The metabolic flux analysis results showed that the flux partitioning at PEP node was stable when glucose was replaced by sorbitol,but the flux partitioning at PYR and AcCoA nodes changed a lot because more reducing power(NADH) was generated to meet the more requirement the synthesis of succinate and ethanol.
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13C metabolic flux analysis(13CMFA)have been the research hotspots of metabolic engineering internationally due to its accuracy and applicability.It is vital that the measurement of 13C labelling pattern of proteinogenic amino acids for 13C metabolic flux analysis.To acquire 13C-labelling proteinogenic amino acids,Pseudomonas denitrifican which products Vitamin B12 was firstly fed with mimimal culture medium contained 20% U-13C and 80% natural glucose,after the culture reached a steady state,then about 20 mg biomass was hydrolyzed by 1 ml of 6 mol/L hydrochloric acid for 24h at 110℃.Then amino acids was separated,concentrated,evaporated in a vacuum,and derivatized with MBDSTFA,TBDMS-derivatized amino acids can be observed by GC-MS last we get 13C labelling pattern of fifteen aminio acids through mass spectrum.The experimental methods and sample preparation offers referential value for the development of 13C metabolic flux analysis in our courtry.
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The zinc chloride and cystine resistant strain of S.cerevisiae YZM-14(ZnCl2r,Cysr) was screened with the mutant processing of the protoplast of S.cerevisiae by combinative mutagens of ultraviolet and nitrite.The glutathione(GSH) production(84.72 mg/L),dry cell weight(7.63 g/L) and the intracellular GSH content(11.10 mg/g) of YZM-14 were 2.79,1.63 and 1.71 times compared with that of the initial strain.The biosynthetic process of GSH was divided into three phases according to the time course of the specific cell growth rate and GSH yielding coefficient.In the second phase,the metabolic flux of the pentose phosphate pathway and the GSH precursors biosynthetic pathway of the mutant strain increased by 8.1 mmol/(g?h),compared with that of the initial strain.Furthermore,the metabolic flux of the organic acids secretion of the mutant strain decreased.Through these mechanisms,the utilization efficiency of the carbon sources was enhanced and high production of GSH was obtained.
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In this paper, metabolic networks of the Corynebacterium glutamicum GWY020 and the two de-rivatives carrying additional mutations HUI821and GUI089 were established and modified. The concentra-tions of extra-cellular metabolites were determined under sub-steady-state (50 h~52 h) of the batch culture. The metabolic flux distribution maps of the three strains were obtained, compared and analyzed. These re-sults indicate that the introduction of analog supersensitive marker or analog resistant marker skew the metabolic flux towards the formation of L-Arginine. This study revealed the usefulness of the metabolic flux analysis as a tool for verification of existing production strains. The analysis may play an important role in helping us to rationally re-design metabolism for further improvement of fermentation process.
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Using metabolic flux balance model , the metabolic flux balance of L- v aline synthesis was established in this paper by material balances and linear p rogramming method. The analysis results indicate that 62.8% metabolic flux ent er ed EMP pathway and 38.2% metabolic flux entered the HMP pathway. And only 9.2 % c arbon entered the TCA cycle. But comparing to the optimal flux distributions of 92.31, the production of L-valine should be improved from the genetic manipula ti on and fermentation control through reducing byproduct of amino acid and decreas ing the metabolic flux.