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Metabolic Engineering Sep 2023Cyanobacteria are attracting increasing attention as a photosynthetic chassis organism for diverse biochemical production, however, photoautotrophic production remains...
Cyanobacteria are attracting increasing attention as a photosynthetic chassis organism for diverse biochemical production, however, photoautotrophic production remains inefficient. Photomixotrophy, a method where sugar is used to supplement baseline autotrophic metabolism in photosynthetic hosts, is becoming increasingly popular for enhancing sustainable bioproduction with multiple input energy streams. In this study, the commercially relevant diacid, succinate, was produced photomixotrophically. Succinate is an important industrial chemical that can be used for the production of a wide array of products, from pharmaceuticals to biopolymers. In this system, the substrate, glucose, is transported by a proton symporter and the product, succinate, is hypothesized to be transported by another proton symporter, but in the opposite direction. Thus, low pH is required for the import of glucose and high pH is required for the export of succinate. Succinate production was initiated in a pH 7 medium containing bicarbonate. Glucose was efficiently imported at around neutral pH. Utilization of bicarbonate by CO fixation raised the pH of the medium. As succinate, a diacid, was produced, the pH of the medium dropped. By repeating this cycle with additional pH adjustment, those contradictory requirements for transport were overcome. pH affects a variety of biological factors and by cycling from high pH to neutral pH processes such as CO fixation rates and CO solubility can vary. In this study the engineered strains produced succinate during fluctuating pH conditions, achieving a titer of 5.0 g L after 10 days under shake flask conditions. These results demonstrate the potential for photomixotrophic production as a viable option for the large-scale production of succinate.
Topics: Succinic Acid; Carbon Dioxide; Protons; Bicarbonates; Metabolic Engineering; Succinates; Glucose; Hydrogen-Ion Concentration; Symporters
PubMed: 37499856
DOI: 10.1016/j.ymben.2023.07.008 -
JCI Insight Sep 2023Lung contusion and gastric aspiration (LC and GA) are major risk factors for developing acute respiratory distress following trauma. Hypoxia from lung injury is mainly...
Lung contusion and gastric aspiration (LC and GA) are major risk factors for developing acute respiratory distress following trauma. Hypoxia from lung injury is mainly regulated by hypoxia-inducible factor 1α (HIF-1α). Published data from our group indicate that HIF-1α regulation in airway epithelial cells (AEC) drives the acute inflammatory response following LC and GA. Metabolomic profiling and metabolic flux of Type II AEC following LC revealed marked increases in glycolytic and TCA intermediates in vivo and in vitro that were HIF-1α dependent. GLUT-1/4 expression was also increased in HIF-1α+/+ mice, suggesting that increased glucose entry may contribute to increased intermediates. Importantly, lactate incubation in vitro on Type II cells did not significantly increase the inflammatory byproduct IL-1β. Contrastingly, succinate had a direct proinflammatory effect on human small AEC by IL-1β generation in vitro. This effect was reversed by dimethylmalonate, suggesting an important role for succinate dehydrogenase in mediating HIF-1α effects. We confirmed the presence of the only known receptor for succinate binding, SUCNR1, on Type II AEC. These results support the hypothesis that succinate drives HIF-1α-mediated airway inflammation following LC. This is the first report to our knowledge of direct proinflammatory activation of succinate in nonimmune cells such as Type II AEC in direct lung injury models.
Topics: Humans; Animals; Mice; Succinic Acid; Lung Injury; Succinates; Respiratory Distress Syndrome; Epithelial Cells; Hypoxia; Inflammation; Lung
PubMed: 37737265
DOI: 10.1172/jci.insight.166860 -
Journal of Innate Immunity 2023Innate immune cells play a crucial role in responding to microbial infections, but their improper activation can also drive inflammatory disease. For this reason, their... (Review)
Review
BACKGROUND
Innate immune cells play a crucial role in responding to microbial infections, but their improper activation can also drive inflammatory disease. For this reason, their activation state is governed by a multitude of factors, including the metabolic state of the cell and, more specifically, the individual metabolites which accumulate intracellularly and extracellularly. This relationship is bidirectional, as innate immune cell activation by pathogen-associated molecular patterns causes critical changes in cellular metabolism.
SUMMARY
In this review, we describe the emergence of various "immunometabolites." We outline the general characteristics of these immunometabolites, the conditions under which they accumulate, and their subsequent impact on immune cells. We delve into well-studied metabolites of recent years, such as succinate and itaconate, as well as newly emerging immunometabolites, such as methylglyoxal.
KEY MESSAGES
We hope that this review may be used as a framework for further studies dissecting the mechanisms by which immunometabolites regulate the immune system and provide an outlook to harnessing these mechanisms in the treatment of inflammatory diseases.
Topics: Humans; Succinic Acid; Immunity; Inflammation
PubMed: 37995666
DOI: 10.1159/000535452 -
Current Opinion in Biotechnology Feb 2016Bio-based production of organic acids via microbial fermentation has been traditionally used in food industry. With the recent desire to develop more sustainable... (Review)
Review
Bio-based production of organic acids via microbial fermentation has been traditionally used in food industry. With the recent desire to develop more sustainable bioprocesses for production of fuels, chemicals and materials, the market for microbial production of organic acids has been further expanded as organic acids constitute a key group among top building block chemicals that can be produced from renewable resources. Here we review the current status for production of citric acid and lactic acid, and we highlight the use of modern metabolic engineering technologies to develop high performance microbes for production of succinic acid and 3-hydroxypropionic acid. Also, the key limitations and challenges in microbial organic acids production are discussed.
Topics: Citric Acid; Lactic Acid; Metabolic Engineering; Succinic Acid
PubMed: 26748037
DOI: 10.1016/j.copbio.2015.11.004 -
Biochemical Society Transactions Dec 2021Oxidation of succinate by mitochondria can generate a higher protonmotive force (pmf) than can oxidation of NADH-linked substrates. Fundamentally, this is because of...
Oxidation of succinate by mitochondria can generate a higher protonmotive force (pmf) than can oxidation of NADH-linked substrates. Fundamentally, this is because of differences in redox potentials and gearing. Biology adds kinetic constraints that tune the oxidation of NADH and succinate to ensure that the resulting mitochondrial pmf is suitable for meeting cellular needs without triggering pathology. Tuning within an optimal range is used, for example, to shift ATP consumption between different consumers. Conditions that overcome these constraints and allow succinate oxidation to drive pmf too high can cause pathological generation of reactive oxygen species. We discuss the thermodynamic properties that allow succinate oxidation to drive pmf higher than NADH oxidation, and discuss the evidence for kinetic tuning of ATP production and for pathologies resulting from substantial succinate oxidation in vivo.
Topics: Animals; Energy Metabolism; Mitochondria; Succinic Acid; Thermodynamics
PubMed: 34882231
DOI: 10.1042/BST20211032 -
Biochimica Et Biophysica Acta.... Jan 2023Succinate dehydrogenases (SDHs) and fumarate reductases (FRDs) catalyse the interconversion of succinate and fumarate, a reaction highly conserved in all domains of...
Succinate dehydrogenases (SDHs) and fumarate reductases (FRDs) catalyse the interconversion of succinate and fumarate, a reaction highly conserved in all domains of life. The current classification of SDH/FRDs is based on the structure of the membrane anchor subunits and their cofactors. It is, however, unknown whether this classification would hold in the context of evolution. In this work, a large-scale comparative genomic analysis of complex II addresses the questions of its taxonomic distribution and phylogeny. Our findings report that for types C, D, and F, structural classification and phylogeny go hand in hand, while for types A, B and E the situation is more complex, highlighting the possibility for their classification into subgroups. Based on these findings, we proposed a revised version of the evolutionary scenario for these enzymes in which a primordial soluble module, corresponding to the cytoplasmatic subunits, would give rise to the current diversity via several independent membrane anchor attachment events.
Topics: Multienzyme Complexes; Succinic Acid; Fumarates; Succinates; Catalysis
PubMed: 36084748
DOI: 10.1016/j.bbabio.2022.148916 -
Frontiers in Immunology 2022A Krebs cycle intermediate metabolite, itaconate, has gained attention as a potential antimicrobial and autoimmune disease treatment due to its anti-inflammatory...
A Krebs cycle intermediate metabolite, itaconate, has gained attention as a potential antimicrobial and autoimmune disease treatment due to its anti-inflammatory effects. While itaconate and its derivatives pose an attractive therapeutic option for the treatment of inflammatory diseases, the effects outside the immune system still remain limited, particularly in the muscle. Therefore, we endeavored to determine if itaconate signaling impacts muscle differentiation. Utilizing the well-established C2C12 model of myogenesis, we evaluated the effects of itaconate and its derivatives on transcriptional and protein markers of muscle differentiation as well as mitochondrial function. We found itaconate and the derivatives dimethyl itaconate and 4-octyl itaconate disrupt differentiation media-induced myogenesis. A primary biological effect of itaconate is a succinate dehydrogenase (SDH) inhibitor. We find the SDH inhibitors dimethyl malonate and harzianopyridone phenocopie the anti-myogenic effects of itaconate. Furthermore, we find treatment with exogenous succinate results in blunted myogenesis. Together our data indicate itaconate and its derivatives interfere with myogenesis, potentially through inhibition of SDH and subsequent succinate accumulation. We also show 4-octyl itaconate suppresses injury-induced MYOG expression . More importantly, our findings suggest the therapeutic potential of itaconate, and its derivatives could be limited due to deleterious effects on myogenesis.
Topics: Muscle Development; Signal Transduction; Succinates; Succinic Acid
PubMed: 35265064
DOI: 10.3389/fimmu.2022.748375 -
Frontiers in Immunology 2022Succinate is at the crossroads of multiple metabolic pathways and plays a role in several immune responses acting as an inflammation signal. However, whether succinate...
Succinate is at the crossroads of multiple metabolic pathways and plays a role in several immune responses acting as an inflammation signal. However, whether succinate regulates antiviral immune response remains unclear. Here, we found that the production of succinate was reduced in RAW264.7 cells during vesicular stomatitis virus (VSV) infection. Using diethyl succinate to pretreat the mouse peritoneal macrophages and RAW264.7 cells before VSV infection, the production of interferon-β (IFN-β), chemokine (C-X-C motif) ligand 10 (CXCL-10), and IFN-stimulated genes 15 (ISG15) was significantly decreased, following which the VSV replication in diethyl succinate-pretreated cells was obviously increased. Moreover, succinate decreased the expression of IFN-β in serum, lung, and spleen derived from the VSV-infected mice. The overall survival rate in the VSV-infected mice with diethyl succinate pretreatment was also remarkably downregulated. Furthermore, we identified that succinate inhibited the activation of MAVS-TBK1-IRF3 signaling by suppressing the formation of MAVS aggregates. Our findings provide previously unrecognized roles of succinate in antiviral immune response and establish a novel link between metabolism and innate immune response.
Topics: Animals; Immunity, Innate; Interferon-beta; Mice; Succinic Acid; Vesicular stomatitis Indiana virus
PubMed: 35309330
DOI: 10.3389/fimmu.2022.816378 -
Journal of the American Heart... Jul 2022Background The metabolite succinate accumulates during cardiac ischemia. Within 5 minutes of reperfusion, succinate returns to baseline levels via both its release...
Background The metabolite succinate accumulates during cardiac ischemia. Within 5 minutes of reperfusion, succinate returns to baseline levels via both its release from cells and oxidation by mitochondrial complex II. The latter drives reactive oxygen species (ROS) generation and subsequent opening of the mitochondrial permeability transition (PT) pore, leading to cell death. Targeting succinate dynamics (accumulation/oxidation/release) may be therapeutically beneficial in cardiac ischemia-reperfusion (IR) injury. It has been proposed that blocking MCT1 (monocarboxylate transporter 1) may be beneficial in IR injury, by preventing succinate release and subsequent engagement of downstream inflammatory signaling pathways. In contrast, herein we hypothesized that blocking MCT1 would retain succinate in cells, exacerbating ROS generation and IR injury. Methods and Results Using the mitochondrial ROS probe mitoSOX and a custom-built murine heart perfusion rig built into a spectrofluorometer, we measured ROS generation in situ during the first moments of reperfusion. We found that acute MCT1 inhibition enhanced mitochondrial ROS generation at reperfusion and worsened IR injury (recovery of function and infarct size). Both of these effects were abrogated by tandem inhibition of mitochondrial complex II, suggesting that succinate retention worsens IR because it drives more mitochondrial ROS generation. Furthermore, using the PT pore inhibitor cyclosporin A, along with monitoring of PT pore opening via the mitochondrial membrane potential indicator tetramethylrhodamine ethyl ester, we herein provide evidence that ROS generation during early reperfusion is upstream of the PT pore, not downstream as proposed by others. In addition, pore opening was exacerbated by MCT1 inhibition. Conclusions Together, these findings highlight the importance of succinate dynamics and mitochondrial ROS generation as key determinants of PT pore opening and IR injury outcomes.
Topics: Animals; Ischemia; Mice; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Reactive Oxygen Species; Reperfusion; Reperfusion Injury; Succinic Acid
PubMed: 35766275
DOI: 10.1161/JAHA.122.026135 -
Reviews in Endocrine & Metabolic... Dec 2019There is now a wealth of evidence showing that communication between microbiota and the host is critical to sustain the vital functions of the healthy host, and... (Review)
Review
There is now a wealth of evidence showing that communication between microbiota and the host is critical to sustain the vital functions of the healthy host, and disruptions of this homeostatic coexistence are known to be associated with a range of diseases including obesity and type 2 diabetes. Microbiota-derived metabolites act both as nutrients and as messenger molecules and can signal to distant organs in the body to shape host pathophysiology. In this review, we provide a new perspective on succinate as a gut microbiota-derived metabolite with a key role governing intestinal homeostasis and energy metabolism. Thus, succinate is not merely a major intermediary of the TCA traditionally considered as an extracellular danger signal in the host, but also a by-product of some bacteria and a primary cross-feeding metabolite between gut resident microbes. In addition to maintain a healthy microbiome, specific functions of microbiota-derived succinate in peripheral tissues regulating host nutrient metabolism should not be rule out. Indeed, recent research point to some probiotic interventions directed to modulate succinate levels in the intestinal lumen, as a new microbiota-based therapies to treat obesity and related co-morbidities. While further research is essential, a large body of evidence point to succinate as a new strategic mediator in the microbiota-host cross-talk, which might provide the basis for new therapeutically approaches in a near future.
Topics: Animals; Gastrointestinal Microbiome; Humans; Metabolic Diseases; Succinic Acid
PubMed: 31654259
DOI: 10.1007/s11154-019-09513-z