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Biochimica Et Biophysica Acta.... Nov 2020Mannose transporters constitute a superfamily (Man-PTS) of the Phosphoenolpyruvate Carbohydrate Phosphotransferase System (PTS). The membrane complexes are homotrimers... (Review)
Review
Mannose transporters constitute a superfamily (Man-PTS) of the Phosphoenolpyruvate Carbohydrate Phosphotransferase System (PTS). The membrane complexes are homotrimers of protomers consisting of two subunits, IIC and IID. The two subunits without recognizable sequence similarity assume the same fold, and in the protomer are structurally related by a two fold pseudosymmetry axis parallel to membrane-plane (Liu et al. (2019) Cell Research 29 680). Two reentrant loops and two transmembrane helices of each subunit together form the N-terminal transport domain. Two three-helix bundles, one of each subunit, form the scaffold domain. The protomer is stabilized by a helix swap between these bundles. The two C-terminal helices of IIC mediate the interprotomer contacts. PTS occur in bacteria and archaea but not in eukaryotes. Man-PTS are abundant in Gram-positive bacteria living on carbohydrate rich mucosal surfaces. A subgroup of IICIID complexes serve as receptors for class IIa bacteriocins and as channel for the penetration of bacteriophage lambda DNA across the inner membrane. Some Man-PTS are associated with host-pathogen and -symbiont processes.
Topics: Bacterial Proteins; Bacteriocins; Bacteriophages; Gram-Positive Bacteria; Mannose; Phosphotransferases; Protein Conformation, alpha-Helical; Protein Domains
PubMed: 32710850
DOI: 10.1016/j.bbamem.2020.183412 -
Horticulture Research 2022The shikimate pathway, the seven enzymatic steps that synthesize chorismate from phosphoenolpyruvate and erythrose 4-phosphate, produces the last common precursor of the...
The shikimate pathway, the seven enzymatic steps that synthesize chorismate from phosphoenolpyruvate and erythrose 4-phosphate, produces the last common precursor of the three aromatic amino acids. It is firmly established that all seven enzymes are present in plastids, and it is generally accepted that this organelle is likely the sole location for production of chorismate in plants. However, recently a growing body of evidence has provided support for a previous proposal that at least portions of the pathway are duplicated in the cytosol, referred to as the Dual Pathway Hypothesis. Here I revisit this obscure hypothesis by reviewing the findings that provided the original basis for its formulation as well as more recent results that provide fresh support for a possible extra-plastidial shikimate pathway duplication. Similarities between this possible intercompartmental metabolic redundancy and that of terpenoid metabolism are used to discuss potential advantages of pathway duplication, and the translational implications of the Dual Pathway Hypothesis for metabolic engineering are noted.
PubMed: 35350169
DOI: 10.1093/hr/uhac052 -
Metabolites Sep 2023Obesity is a multifactorial disorder that is remarkably heterogeneous. It presents itself in a variety of phenotypes that can be metabolically unhealthy or healthy,... (Review)
Review
Obesity is a multifactorial disorder that is remarkably heterogeneous. It presents itself in a variety of phenotypes that can be metabolically unhealthy or healthy, associate with no or multiple metabolic risk factors, gain extreme body weight (super-responders), as well as resist obesity despite the obesogenic environment (non-responders). Progression to obesity is ultimately linked to the overall net energy balance and activity of different metabolic fluxes. This is particularly evident from variations in fatty acids oxidation, metabolic fluxes through the pyruvate-phosphoenolpyruvate-oxaloacetate node, and extracellular accumulation of Krebs cycle metabolites, such as citrate. Patterns of fat accumulation with a focus on visceral and ectopic adipose tissue, microbiome composition, and the immune status of the gastrointestinal tract have emerged as the most promising targets that allow personalization of obesity and warrant further investigations into the critical issue of a wider and long-term weight control. Advances in understanding the biochemistry mechanisms underlying the heterogenous obesity phenotypes are critical to the development of targeted strategies to maintain healthy weight.
PubMed: 37755296
DOI: 10.3390/metabo13091016 -
Scientific Reports Feb 2020Phosphoenolpyruvate carboxylase (PEPc) is an essential enzyme in plants. A photosynthetic form is present both as dimer and tetramer in C4 and CAM metabolism....
Phosphoenolpyruvate carboxylase (PEPc) is an essential enzyme in plants. A photosynthetic form is present both as dimer and tetramer in C4 and CAM metabolism. Additionally, non-photosynthetic PEPcs are also present. The single, non-photosynthetic PEPc of the unicellular cyanobacterium Synechococcus PCC 7002 (Synechococcus), involved in the TCA cycle, was examined. Using size exclusion chromatography (SEC) and small angle X-ray scattering (SAXS), we observed that PEPc in Synechococcus exists as both a dimer and a tetramer. This is the first demonstration of two different oligomerization states of a non-photosynthetic PEPc. High concentration of Mg, the substrate PEP and a combination of low concentration of Mg and HCO induced the tetramer form of the carboxylase. Using SEC-SAXS analysis, we showed that the oligomerization state of the carboxylase is concentration dependent and that, among the available crystal structures of PEPc, the scattering profile of PEPc of Synechococcus agrees best with the structure of PEPc from Escherichia coli. In addition, the kinetics of the tetramer purified in presence of Mg using SEC, and of the mixed population purified in presence of Mg using a Strep-tagged column were examined. Moreover, the enzyme showed interesting allosteric regulation, being activated by succinate and inhibited by glutamine, and not affected by either malate, 2-oxoglutarate, aspartic acid or citric acid.
Topics: Allosteric Regulation; Bacterial Proteins; Chromatography, Gel; Crystallization; Crystallography, X-Ray; Dimerization; Escherichia coli; Glutamine; Magnesium; Phosphoenolpyruvate Carboxylase; Protein Conformation; Scattering, Small Angle; Synechococcus
PubMed: 32107404
DOI: 10.1038/s41598-020-60249-2 -
International Journal of Oral Science Nov 2022As an important enzyme for gluconeogenesis, mitochondrial phosphoenolpyruvate carboxykinase (PCK2) has further complex functions beyond regulation of glucose metabolism....
As an important enzyme for gluconeogenesis, mitochondrial phosphoenolpyruvate carboxykinase (PCK2) has further complex functions beyond regulation of glucose metabolism. Here, we report that conditional knockout of Pck2 in osteoblasts results in a pathological phenotype manifested as craniofacial malformation, long bone loss, and marrow adipocyte accumulation. Ablation of Pck2 alters the metabolic pathways of developing bone, particularly fatty acid metabolism. However, metformin treatment can mitigate skeletal dysplasia of embryonic and postnatal heterozygous knockout mice, at least partly via the AMPK signaling pathway. Collectively, these data illustrate that PCK2 is pivotal for bone development and metabolic homeostasis, and suggest that regulation of metformin-mediated signaling could provide a novel and practical strategy for treating metabolic skeletal dysfunction.
Topics: Mice; Animals; Metformin; Phosphoenolpyruvate Carboxykinase (ATP); Gluconeogenesis; Mice, Knockout
PubMed: 36376276
DOI: 10.1038/s41368-022-00204-1 -
Microbiology Spectrum Sep 2023Glutathione (GSH) is an essential component of the glutaredoxin (Grx) system, and it is synthesized by the enzyme glutathione synthase GshF in . GSH plays a crucial role...
Glutathione (GSH) is an essential component of the glutaredoxin (Grx) system, and it is synthesized by the enzyme glutathione synthase GshF in . GSH plays a crucial role in regulating virulence by modifying the virulence factors LLO and PrfA. In this study, we investigated the involvement of GshF in oxidative tolerance and intracellular infection. Our findings revealed that the deletion of resulted in a significant reduction in bacterial growth when exposed to diamide and copper ions stress. More importantly, this deletion also impaired the efficiency of invasion and proliferation in macrophages and mice organs. Furthermore, GshF influenced global transcriptional profiles, including carbohydrate and amino acid metabolism, particularly those related to the phosphoenolpyruvate-carbohydrate phosphotransferase system (PTS) genes , under oxidative stress conditions. In the wild-type strain, the transcription of was notably downregulated in response to copper ions and diamide stress compared to normal conditions. However, in the absence of , the transcripts of were upregulated in response to these stress conditions. Notably, the deletion of () enhanced oxidative stress tolerance to copper ions, whereas overexpression of reduced this resistance. In conclusion, our study provides the first evidence that GshF plays a crucial role in bacterial antioxidation through the regulation of .IMPORTANCE has developed various mechanisms to withstand oxidative stress, including the thioredoxin and glutaredoxin systems. However, the specific role of the glutathione synthase GshF, responsible for synthesizing GSH in , in oxidative tolerance remains unclear. This study aimed to elucidate the relationship between GshF and oxidative tolerance in by examining the efficiency of invasion and proliferation in macrophages and mice organs, as well as analyzing global transcriptional profiles under oxidative stress conditions. The results revealed that GshF plays a significant role in ' response to oxidative stress. Notably, GshF acts to suppress the transcription of phosphoenolpyruvate-carbohydrate phosphotransferase system genes , among which () was identified as the most critical gene for resisting oxidative stress. These findings enhance our understanding of how adapts to its environment and provide valuable insights for investigating the environmental adaptation mechanisms of other pathogenic bacteria.
PubMed: 37668404
DOI: 10.1128/spectrum.02365-23 -
Plants (Basel, Switzerland) Jul 2023Protein phosphatase 2A (PP2A) is a heterotrimeric conserved serine/threonine phosphatase complex that includes catalytic, scaffolding, and regulatory subunits. The 3 A...
Protein phosphatase 2A (PP2A) is a heterotrimeric conserved serine/threonine phosphatase complex that includes catalytic, scaffolding, and regulatory subunits. The 3 A subunits, 17 B subunits, and 5 C subunits that are encoded by the Arabidopsis genome allow 255 possible PP2A holoenzyme combinations. The regulatory subunits are crucial for substrate specificity and PP2A complex localization and are classified into the B, B', and B" non-related families in land plants. In Arabidopsis, the close homologs B'η, B'θ, B'γ, and B'ζ are further classified into a subfamily of B' called B'η. Previous studies have suggested that mitochondrial targeted PP2A subunits (B'ζ) play a role in energy metabolism and plant innate immunity. Potentially, the PP2A-B'ζ holoenzyme is involved in the regulation of the mitochondrial succinate/fumarate translocator, and it may affect the enzymes involved in energy metabolism. To investigate this hypothesis, the interactions between PP2A-B'ζ and the enzymes involved in the mitochondrial energy flow were investigated using bimolecular fluorescence complementation in tobacco and onion cells. Interactions were confirmed between the B'ζ subunit and the Krebs cycle proteins succinate/fumarate translocator (mSFC1), malate dehydrogenase (mMDH2), and aconitase (ACO3). Additional putative interacting candidates were deduced by comparing the enriched phosphoproteomes of wild type and B'ζ mutants: the mitochondrial regulator Arabidopsis pentatricopeptide repeat 6 (PPR6) and the two metabolic enzymes phosphoenolpyruvate carboxylase (PPC3) and phosphoenolpyruvate carboxykinase (PCK1). Overall, this study identifies potential PP2A substrates and highlights the role of PP2A in regulating energy metabolism in mitochondria.
PubMed: 37447147
DOI: 10.3390/plants12132586 -
Bio-protocol Dec 2021Phosphoenolpyruvate carboxylase (PEPC) catalyzes a critical step in carbon metabolism in plants and bacteria, the irreversible reaction between bicarbonate and...
Phosphoenolpyruvate carboxylase (PEPC) catalyzes a critical step in carbon metabolism in plants and bacteria, the irreversible reaction between bicarbonate and phosphoenolpyruvate to produce the C compound oxaloacetate. This enzyme is particularly important in the context of C photosynthesis, where it is the initial carbon-fixing enzyme. Many studies have used kinetic approaches to characterize the properties of PEPCs from different species, different post-translational states, and after mutagenesis. Most of these studies have worked at a fixed saturating concentration of bicarbonate. Controlling the concentration of bicarbonate is difficult at low concentrations because of equilibration with atmospheric CO. We describe here a simple, repeatable, and gas-tight assay system for PEPC that allows bicarbonate concentrations to be controlled above 50 µM.
PubMed: 35087923
DOI: 10.21769/BioProtoc.4264 -
Molecules and Cells Apr 2022Nuclear receptor coactivator 6 (NCOA6) is a transcriptional coactivator of nuclear receptors and other transcription factors. A general knockout mouse was previously...
Nuclear receptor coactivator 6 (NCOA6) is a transcriptional coactivator of nuclear receptors and other transcription factors. A general knockout mouse was previously shown to be embryonic lethal, but we here generated liver-specific knockout ( LKO) mice to investigate the metabolic function of NCOA6 in the liver. These LKO mice exhibited similar blood glucose and insulin levels to wild type but showed improvements in glucose tolerance, insulin sensitivity, and pyruvate tolerance. The decrease in glucose production from pyruvate in these LKO mice was consistent with the abrogation of the fasting-stimulated induction of gluconeogenic genes, phosphoenolpyruvate carboxykinase 1 () and glucose-6-phosphatase (). The forskolin-stimulated inductions of and were also dramatically reduced in primary hepatocytes isolated from LKO mice, whereas the expression levels of other gluconeogenic gene regulators, including cAMP response element binding protein (), forkhead box protein O1 and peroxisome proliferator-activated receptor γ coactivator 1α, were unaltered in the LKO mouse livers. CREB phosphorylation via fasting or forskolin stimulation was normal in the livers and primary hepatocytes of the LKO mice. Notably, it was observed that CREB interacts with NCOA6. The transcriptional activity of CREB was found to be enhanced by NCOA6 in the context of and promoters. NCOA6-dependent augmentation was abolished in cAMP response element (CRE) mutant promoters of the and genes. Our present results suggest that NCOA6 regulates hepatic gluconeogenesis by modulating glucagon/cAMP-dependent gluconeogenic gene transcription through an interaction with CREB.
Topics: Animals; Colforsin; Cyclic AMP Response Element-Binding Protein; Gluconeogenesis; Glucose; Glucose-6-Phosphatase; Hepatocytes; Liver; Mice; Mice, Inbred C57BL; Mice, Knockout; Nuclear Receptor Coactivators; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Pyruvic Acid
PubMed: 35258009
DOI: 10.14348/molcells.2022.2222 -
Experimental and Therapeutic Medicine Mar 2022Type 1 diabetes (T1D) is characterized by dysregulated blood glucose and liver metabolism. In previous studies, niclosamide ethanolamine salt (NEN) and artemether (Art)...
Type 1 diabetes (T1D) is characterized by dysregulated blood glucose and liver metabolism. In previous studies, niclosamide ethanolamine salt (NEN) and artemether (Art) displayed significant hypoglycemic effects. However, their combined therapeutic effects on the liver in T1D have remained elusive. In the present study, T1D mice were established and randomly allocated into groups. Following treatment, the physiological and metabolic parameters, including liver function, glycogen content, glucose-6-phosphatase (G6Pase) protein expression levels, mitochondrial biogenesis and mitochondrial metabolism were analyzed. Compared with the NEN or Art treatments alone, their combination improved glycometabolism and the symptoms of diabetes. Combined treatment with NEN and Art also significantly ameliorated liver injury and increased liver glycogen storage. Furthermore, combinatorial treatment significantly downregulated hepatic G6Pase protein expression levels and regulated mitochondrial biogenesis. NEN and Art increased the respiratory exchange rate and reduced mitochondrial phosphoenolpyruvate carboxykinase and branched-chain α-keto acid dehydrogenase complex protein expression levels, whereby the effects were obviously enhanced by their application as a combined treatment. In conclusion, the present study confirmed that combined treatment with NEN and Art improved glycometabolism and liver function in T1D mice and the therapeutic effects may be partially associated with the regulation of liver mitochondria.
PubMed: 35222716
DOI: 10.3892/etm.2022.11164