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1.
Faraday Discuss ; 252(0): 295-305, 2024 Sep 11.
Article de Anglais | MEDLINE | ID: mdl-38847587

RÉSUMÉ

Genetic code expansion has emerged as a powerful tool in enzyme design and engineering, providing new insights into sophisticated catalytic mechanisms and enabling the development of enzymes with new catalytic functions. In this regard, the non-canonical histidine analogue Nδ-methylhistidine (MeHis) has proven especially versatile due to its ability to serve as a metal coordinating ligand or a catalytic nucleophile with a similar mode of reactivity to small molecule catalysts such as 4-dimethylaminopyridine (DMAP). Here we report the development of a highly efficient aminoacyl tRNA synthetase (G1PylRSMIFAF) for encoding MeHis into proteins, by transplanting five known active site mutations from Methanomethylophilus alvus (MaPylRS) into the single domain PylRS from Methanogenic archaeon ISO4-G1. In contrast to the high concentrations of MeHis (5-10 mM) needed with the Ma system, G1PylRSMIFAF can operate efficiently using MeHis concentrations of ∼0.1 mM, allowing more economical production of a range of MeHis-containing enzymes in high titres. Interestingly G1PylRSMIFAF is also a 'polyspecific' aminoacyl tRNA synthetase (aaRS), enabling incorporation of five different non-canonical amino acids (ncAAs) including 3-pyridylalanine and 2-fluorophenylalanine. This study provides an important step towards scalable production of engineered enzymes that contain non-canonical amino acids such as MeHis as key catalytic elements.


Sujet(s)
Amino acyl-tRNA synthetases , Amino acyl-tRNA synthetases/métabolisme , Amino acyl-tRNA synthetases/génétique , Amino acyl-tRNA synthetases/composition chimique , Méthylhistidines/métabolisme , Méthylhistidines/composition chimique , Lysine/composition chimique , Lysine/métabolisme , Lysine/analogues et dérivés , Domaine catalytique , Histidine/composition chimique , Histidine/métabolisme , Histidine/analogues et dérivés
2.
Nephrol Dial Transplant ; 37(10): 1951-1961, 2022 09 22.
Article de Anglais | MEDLINE | ID: mdl-35234930

RÉSUMÉ

BACKGROUND: Chronic kidney disease is an important contributor to morbidity and mortality. 3-methylhistidine (3-MH) is the by-product of actin and myosin degradation reflecting skeletal muscle turnover. Markedly elevated 3-MH levels have been documented in uraemic patients, but the interpretation of high 3-MH concentration in maintenance haemodialysis (MHD) patients remains unclear. Indeed, it is not known whether elevated serum 3-MH levels are a marker of excessive muscle catabolism or a better lean tissue mass. Here, we evaluated the association between serum 3-MH levels and clinical outcomes in these patients. METHODS: Serum 3-MH concentration was measured by reverse-phase liquid chromatography/tandem mass spectrometry in a cohort of MHD patients. We analysed the relationships between various clinical/laboratory indices, lean tissue mass measured by bioimpedance spectroscopy, mortality and cardiovascular (CV) events. RESULTS: Serum 3-MH concentration was positively correlated with serum albumin, normalized protein catabolic rate (nPCR), simplified creatinine index (SCI) and lean tissue mass. Of 291 MHD patients, during a mean follow-up of 847 days, 91 patients died and 101 patients experienced a CV event. Survival was significantly better in patients with high 3-MH concentrations (P = .002). A higher level of 3-MH was also associated with a lower CV mortality and lower incidence of CV events (P = .015 and P < .001, respectively). Low serum 3-MH levels remained significantly associated with CV events but not with mortality after adjustment for demographic, metabolic and CV risk factors. CONCLUSION: Elevated serum 3-MH concentration appears to be a marker of better lean tissue mass and nutritional status. Low serum 3-MH is a robust and independent predictor of CV events in the MHD population.


Sujet(s)
Actines , Défaillance rénale chronique , Méthylhistidines , Dialyse rénale , Actines/métabolisme , Marqueurs biologiques/analyse , Marqueurs biologiques/métabolisme , Créatinine , Humains , Défaillance rénale chronique/sang , Défaillance rénale chronique/métabolisme , Défaillance rénale chronique/thérapie , Méthylhistidines/sang , Méthylhistidines/métabolisme , Sérumalbumine/analyse , Sérumalbumine/métabolisme
3.
Open Biol ; 12(1): 210262, 2022 01.
Article de Anglais | MEDLINE | ID: mdl-35042403

RÉSUMÉ

Ovothiols are π-methyl-5-thiohistidines produced in great amounts in sea urchin eggs, where they can act as protective agents against the oxidative burst at fertilization and environmental stressors during development. Here we examined the biological relevance of ovothiol during the embryogenesis of the sea urchin Paracentrotus lividus by assessing the localization of the key biosynthetic enzyme OvoA, both at transcript and protein level, and perturbing its protein translation by morpholino antisense oligonucleotide-mediated knockdown experiments. In addition, we explored the possible involvement of ovothiol in the inflammatory response by assessing ovoA gene expression and protein localization following exposure to bacterial lipopolysaccharide. The results of the present study suggest that ovothiol may be a key regulator of cell proliferation in early developing embryos. Moreover, the localization of OvoA in key larval cells and tissues, in control and inflammatory conditions, suggests that ovothiol may ensure larval skeleton formation and mediate inflammatory processes triggered by bacterial infection. This work significantly contributes to the understanding of the biological function of ovothiols in marine organisms, and may provide new inspiration for the identification of the biological activities of ovothiols in humans, considering the pharmacological potential of these molecules.


Sujet(s)
Paracentrotus , Animaux , Embryon non mammalien , Humains , Larve , Méthylhistidines/métabolisme , Paracentrotus/métabolisme
4.
J Biol Chem ; 297(5): 101230, 2021 11.
Article de Anglais | MEDLINE | ID: mdl-34562450

RÉSUMÉ

Protein methylation is one of the most common post-translational modifications observed in basic amino acid residues, including lysine, arginine, and histidine. Histidine methylation occurs on the distal or proximal nitrogen atom of its imidazole ring, producing two isomers: Nτ-methylhistidine or Nπ-methylhistidine. However, the biological significance of protein histidine methylation remains largely unclear owing in part to the very limited knowledge about its contributing enzymes. Here, we identified mammalian seven-ß-strand methyltransferase METTL9 as a histidine Nπ-methyltransferase by siRNA screening coupled with methylhistidine analysis using LC-tandem MS. We demonstrated that METTL9 catalyzes Nπ-methylhistidine formation in the proinflammatory protein S100A9, but not that of myosin light chain kinase MYLK2, in vivo and in vitro. METTL9 does not affect the heterodimer formation of S100A9 and S100A8, although Nπ-methylation of S100A9 at His-107 overlaps with a zinc-binding site, attenuating its affinity for zinc. Given that S100A9 exerts an antimicrobial activity, probably by chelation of zinc essential for the growth of bacteria and fungi, METTL9-mediated S100A9 methylation might be involved in the innate immune response to bacterial and fungal infection. Thus, our findings suggest a functional consequence for protein histidine Nπ-methylation and may add a new layer of complexity to the regulatory mechanisms of post-translational methylation.


Sujet(s)
Calgranuline B , Methyltransferases , Maturation post-traductionnelle des protéines , Petit ARN interférent , Animaux , Calgranuline B/génétique , Calgranuline B/métabolisme , Cellules HEK293 , Cellules HeLa , Humains , Inflammation/génétique , Inflammation/métabolisme , Méthylation , Méthylhistidines/métabolisme , Methyltransferases/génétique , Methyltransferases/métabolisme , Souris , Petit ARN interférent/génétique , Petit ARN interférent/métabolisme
5.
Nutrients ; 13(7)2021 Jul 13.
Article de Anglais | MEDLINE | ID: mdl-34371902

RÉSUMÉ

There is ongoing debate as to whether or not α-hydroxyisocaproic acid (HICA) positively regulates skeletal muscle protein synthesis resulting in the gain or maintenance of skeletal muscle. We investigated the effects of HICA on mouse C2C12 myotubes under normal conditions and during cachexia induced by co-exposure to TNFα and IFNγ. The phosphorylation of AMPK or ERK1/2 was significantly altered 30 min after HICA treatment under normal conditions. The basal protein synthesis rates measured by a deuterium-labeling method were significantly lowered by the HICA treatment under normal and cachexic conditions. Conversely, myotube atrophy induced by TNFα/IFNγ co-exposure was significantly improved by the HICA pretreatment, and this improvement was accompanied by the inhibition of iNOS expression and IL-6 production. Moreover, HICA also suppressed the TNFα/IFNγ co-exposure-induced secretion of 3-methylhistidine. These results demonstrated that HICA decreases basal protein synthesis under normal or cachexic conditions; however, HICA might attenuate skeletal muscle atrophy via maintaining a low level of protein degradation under cachexic conditions.


Sujet(s)
Cachexie/traitement médicamenteux , Caproates/pharmacologie , Interféron gamma/toxicité , Interleukine-6/métabolisme , Fibres musculaires squelettiques/effets des médicaments et des substances chimiques , Amyotrophie/traitement médicamenteux , Nitric oxide synthase type II/métabolisme , Facteur de nécrose tumorale alpha/toxicité , AMP-Activated Protein Kinases/métabolisme , Animaux , Cachexie/induit chimiquement , Cachexie/métabolisme , Cachexie/anatomopathologie , Lignée cellulaire , Régulation négative , Extracellular Signal-Regulated MAP Kinases/métabolisme , Méthylhistidines/métabolisme , Souris , Fibres musculaires squelettiques/enzymologie , Fibres musculaires squelettiques/anatomopathologie , Amyotrophie/induit chimiquement , Amyotrophie/métabolisme , Amyotrophie/anatomopathologie , Phosphorylation , Biosynthèse des protéines , Protéolyse
6.
Genome Biol Evol ; 13(9)2021 09 01.
Article de Anglais | MEDLINE | ID: mdl-34272861

RÉSUMÉ

Ovothiols are sulfur-containing amino acids synthesized by marine invertebrates, protozoans, and bacteria. They act as pleiotropic molecules in signaling and protection against oxidative stress. The discovery of ovothiol biosynthetic enzymes, sulfoxide synthase OvoA and ß-lyase OvoB, paves the way for a systematic investigation of ovothiol distribution and molecular diversification in nature. In this work, we conducted genomic and metagenomics data mining to investigate the distribution and diversification of ovothiol biosynthetic enzymes in Bacteria. We identified the bacteria endowed with this secondary metabolic pathway, described their taxonomy, habitat and biotic interactions in order to provide insight into their adaptation to specific environments. We report that OvoA and OvoB are mostly encountered in marine aerobic Proteobacteria, some of them establishing symbiotic or parasitic relationships with other organisms. We identified a horizontal gene transfer event of OvoB from Bacteroidetes living in symbiosis with Hydrozoa. Our search within the Ocean Gene Atlas revealed the occurrence of ovothiol biosynthetic genes in Proteobacteria living in a wide range of pelagic and highly oxygenated environments. Finally, we tracked the evolutionary history of ovothiol biosynthesis from marine bacteria to unicellular eukaryotes and metazoans. Our analysis provides new conceptual elements to unravel the evolutionary and ecological significance of ovothiol biosynthesis.


Sujet(s)
Bactéries , Méthylhistidines , Organismes aquatiques , Bactéries/génétique , Bactéries/métabolisme , Évolution moléculaire , Transfert horizontal de gène , Méthylhistidines/composition chimique , Méthylhistidines/métabolisme
7.
Nat Commun ; 12(1): 891, 2021 02 09.
Article de Anglais | MEDLINE | ID: mdl-33563959

RÉSUMÉ

Post-translational methylation plays a crucial role in regulating and optimizing protein function. Protein histidine methylation, occurring as the two isomers 1- and 3-methylhistidine (1MH and 3MH), was first reported five decades ago, but remains largely unexplored. Here we report that METTL9 is a broad-specificity methyltransferase that mediates the formation of the majority of 1MH present in mouse and human proteomes. METTL9-catalyzed methylation requires a His-x-His (HxH) motif, where "x" is preferably a small amino acid, allowing METTL9 to methylate a number of HxH-containing proteins, including the immunomodulatory protein S100A9 and the NDUFB3 subunit of mitochondrial respiratory Complex I. Notably, METTL9-mediated methylation enhances respiration via Complex I, and the presence of 1MH in an HxH-containing peptide reduced its zinc binding affinity. Our results establish METTL9-mediated 1MH as a pervasive protein modification, thus setting the stage for further functional studies on protein histidine methylation.


Sujet(s)
Méthylhistidines/métabolisme , Methyltransferases/métabolisme , Protéome/métabolisme , Motifs d'acides aminés , Animaux , Cellules cultivées , Histidine/métabolisme , Humains , Mammifères/classification , Mammifères/génétique , Mammifères/métabolisme , Méthylation , Methyltransferases/génétique , Souris , Souris de lignée C57BL , Souris knockout , Mitochondries/métabolisme , Mutation , Maturation post-traductionnelle des protéines , Protéome/composition chimique , Spécificité du substrat , Zinc/métabolisme
8.
Curr Opin Chem Biol ; 59: 111-118, 2020 12.
Article de Anglais | MEDLINE | ID: mdl-32726707

RÉSUMÉ

Sulfoxide synthases are non-heme iron enzymes that catalyze oxidative carbonsulfur bond formation in the biosynthesis of thiohistidines such as ergothioneine and ovothiol. The catalytic mechanism of these enzymes has been studied by protein crystallography, steady-state kinetics, non-natural amino acid incorporation and computational modeling. This review discusses the current status of this research and also highlights similarities between the CS bond forming activity of sulfoxide synthases with that of synthetic coordination compounds.


Sujet(s)
Voies de biosynthèse , Ergothionéine/métabolisme , Ligases/métabolisme , Méthylhistidines/métabolisme , Sulfoxydes/métabolisme , Animaux , Bactéries/enzymologie , Bactéries/métabolisme , Champignons/enzymologie , Champignons/métabolisme , Humains , Modèles moléculaires
9.
Curr Protein Pept Sci ; 21(7): 675-689, 2020.
Article de Anglais | MEDLINE | ID: mdl-32188384

RÉSUMÉ

Protein histidine methylation is a rarely studied posttranslational modification in eukaryotes. Although the presence of N-methylhistidine was demonstrated in actin in the early 1960s, so far, only a limited number of proteins containing N-methylhistidine have been reported, including S100A9, myosin, skeletal muscle myosin light chain kinase (MLCK 2), and ribosomal protein Rpl3. Furthermore, the role of histidine methylation in the functioning of the protein and in cell physiology remains unclear due to a shortage of studies focusing on this topic. However, the molecular identification of the first two distinct histidine-specific protein methyltransferases has been established in yeast (Hpm1) and in metazoan species (actin-histidine N-methyltransferase), giving new insights into the phenomenon of protein methylation at histidine sites. As a result, we are now beginning to recognize protein histidine methylation as an important regulatory mechanism of protein functioning whose loss may have deleterious consequences in both cells and in organisms. In this review, we aim to summarize the recent advances in the understanding of the chemical, enzymological, and physiological aspects of protein histidine methylation.


Sujet(s)
Actines/métabolisme , Histidine/métabolisme , Myosin-Light-Chain Kinase/métabolisme , Protein Methyltransferases/métabolisme , Maturation post-traductionnelle des protéines , Protéines ribosomiques/métabolisme , Actines/génétique , Animaux , Calgranuline B/génétique , Calgranuline B/métabolisme , Histone méthyltransférases/génétique , Histone méthyltransférases/métabolisme , Humains , Méthylation , Méthylhistidines/métabolisme , Methyltransferases/génétique , Methyltransferases/métabolisme , Myosin-Light-Chain Kinase/génétique , Protein Methyltransferases/génétique , Protéine ribosomique L3 , Protéines ribosomiques/génétique , Saccharomyces cerevisiae/enzymologie , Saccharomyces cerevisiae/génétique , Protéines de Saccharomyces cerevisiae/génétique , Protéines de Saccharomyces cerevisiae/métabolisme , Transduction du signal
10.
Biomolecules ; 10(3)2020 02 28.
Article de Anglais | MEDLINE | ID: mdl-32121166

RÉSUMÉ

Reactive oxygen species present a challenge for marine organisms releasing gametes into the water. Thiol-containing molecules protect cells against oxidative stress, and ovothiol (OSH), an antioxidant-reducing mercaptohistidine, has been described as especially relevant in the oocytes of marine invertebrates. Ovothiol synthase (ovoA), in charge of the first step in OSH synthesis, was sequenced in mussels, Mytilus galloprovincialis. Transcription levels of ovoA in mantle did not significantly change along the reproductive cycle. No alterations of ovoA transcription were observed after a laboratory copper (10 µg/L) exposure or in mussels captured in a highly polluted site. Conversely, the metabolomic analysis of the hydrophilic metabolite content in mantle clearly classified mussels according to their site of origin, especially at the most advanced stages of oogenesis. Quantification of OSH-A and -B and glutathione (GSH), revealed stable levels in mantle at early gametogenesis in the unpolluted sampling site, but a strong increase in female mantle previous to spawning in the polluted site. These increased concentrations under pollution suggest that OSH-A accumulates along oogenesis, independent of gene transcription regulation. The concerted accumulation of OSH-A and GSH suggests the building of a balanced cellular redox-system to scavenge ROS produced in the oocyte before and during fertilization.


Sujet(s)
Estuaires , Gamétogenèse , Méthylhistidines/métabolisme , Mytilus/métabolisme , Stress oxydatif , Pollution de l'eau , Animaux , Reproduction
11.
Nature ; 570(7760): 219-223, 2019 06.
Article de Anglais | MEDLINE | ID: mdl-31132786

RÉSUMÉ

The combination of computational design and laboratory evolution is a powerful and potentially versatile strategy for the development of enzymes with new functions1-4. However, the limited functionality presented by the genetic code restricts the range of catalytic mechanisms that are accessible in designed active sites. Inspired by mechanistic strategies from small-molecule organocatalysis5, here we report the generation of a hydrolytic enzyme that uses Nδ-methylhistidine as a non-canonical catalytic nucleophile. Histidine methylation is essential for catalytic function because it prevents the formation of unreactive acyl-enzyme intermediates, which has been a long-standing challenge when using canonical nucleophiles in enzyme design6-10. Enzyme performance was optimized using directed evolution protocols adapted to an expanded genetic code, affording a biocatalyst capable of accelerating ester hydrolysis with greater than 9,000-fold increased efficiency over free Nδ-methylhistidine in solution. Crystallographic snapshots along the evolutionary trajectory highlight the catalytic devices that are responsible for this increase in efficiency. Nδ-methylhistidine can be considered to be a genetically encodable surrogate of the widely employed nucleophilic catalyst dimethylaminopyridine11, and its use will create opportunities to design and engineer enzymes for a wealth of valuable chemical transformations.


Sujet(s)
Évolution moléculaire dirigée , Hydrolases/génétique , Hydrolases/métabolisme , Ingénierie des protéines , 4-Amino-pyridine/analogues et dérivés , 4-Amino-pyridine/métabolisme , Biocatalyse , Domaine catalytique/génétique , Cristallographie aux rayons X , Esters/métabolisme , Code génétique , Hydrolases/composition chimique , Hydrolyse , Méthylhistidines/métabolisme , Modèles moléculaires , Mutagenèse , Mutation , Pyrococcus horikoshii/enzymologie , Pyrococcus horikoshii/génétique , Spécificité du substrat/génétique
12.
Am J Physiol Cell Physiol ; 317(2): C189-C199, 2019 08 01.
Article de Anglais | MEDLINE | ID: mdl-31042421

RÉSUMÉ

Sepsis is a systemic inflammatory response syndrome resulting from infection. This study aimed at exploring the role of microRNA-140 (miR-140) in septic mice. Wnt family member 11 (WNT11) was verified to be a target gene of miR-140 after bioinformatic prediction and dual luciferase reporter gene assay. Importantly, miR-140 negatively regulated WNT11. We initially induced the model of sepsis by endotoxin, and then ectopic expression and knockdown experiments were performed to explore the functional role of miR-140 in sepsis. Additionally, cross-sectional areas of muscle fiber, lactic acid production, 3-methylhistidine (3-MH) and tyrosine (Tyr) production in extensor digitorium longus (EDL) muscles, and serum levels of inflammatory factors were examined. The effect of miR-140 on the expression of WNT signaling pathway-related and apoptosis-related factors in skeletal muscle tissue was determined. The experimental results indicated that upregulated miR-140 or silenced WNT11 increased cross-sectional areas of muscle fiber while decreasing lactic acid production, skeletal muscle cell apoptosis [corresponding to downregulated B cell lymphoma 2 (Bcl-2)-associated X protein (Bax) and caspase-3 and upregulated Bcl-2], and the proteolytic rate of Tyr and 3-MH. Also, overexpressed miR-140 or silenced WNT11 reduced inflammation as reflected by decreased serum levels of IL-6, IL-10, and TNF-α. Furthermore, overexpression of miR-140 was shown to suppress the activation of the WNT signaling pathway, accompanied by decreased expression of WNT11, ß-catenin, and GSK-3ß. Taken together, upregulation of miR-140 could potentially inhibit skeletal muscle lactate release, an indirect measure of glycolysis, and atrophy in septic mice through suppressing the WNT signaling pathway via inhibiting WNT11 expression.


Sujet(s)
Glycolyse , microARN/métabolisme , Muscles squelettiques/métabolisme , Amyotrophie/métabolisme , Sepsie/métabolisme , Protéines de type Wingless/métabolisme , Voie de signalisation Wnt , Animaux , Apoptose , Protéines régulatrices de l'apoptose/métabolisme , Cellules cultivées , Cytokines/sang , Modèles animaux de maladie humaine , Régulation négative , Glycogen synthase kinase 3 beta/génétique , Glycogen synthase kinase 3 beta/métabolisme , Médiateurs de l'inflammation/sang , Acide lactique/métabolisme , Lipopolysaccharides , Mâle , Méthylhistidines/métabolisme , Souris de lignée BALB C , microARN/génétique , Muscles squelettiques/anatomopathologie , Amyotrophie/induit chimiquement , Amyotrophie/génétique , Amyotrophie/anatomopathologie , Sepsie/induit chimiquement , Sepsie/génétique , Sepsie/anatomopathologie , Tyrosine/métabolisme , Protéines de type Wingless/génétique , bêta-Caténine/génétique , bêta-Caténine/métabolisme
13.
J Nutr Biochem ; 65: 26-34, 2019 03.
Article de Anglais | MEDLINE | ID: mdl-30599394

RÉSUMÉ

Vitamin B6 deficiency is associated with cardiovascular disease (CVD). Although plasma biomarkers have been proposed, no studies have yet directly profiled heart tissue, and the mechanisms have to be fully defined. Thus, in order to provide better insight into vitamin B6-deficient effects on cardiac functions, we sought to identify the metabolic profile in heart tissue consequent to change in dietary vitamin B6 levels by applying metabolomics. Heart tissues of rats fed a basal diet containing a marginal vitamin B6-deficient, vitamin B6-recommended or vitamin B6-supplemented level were analyzed by metabolomics analysis. Among over 500 detected metabolites, imidazole metabolites including carnosine, anserine, homocarnosine and histamine exhibited the highest decrease upon vitamin B6 deficiency (>-45%, P<.01), along with their precursors ß-alanine, γ-aminobutyric acid (GABA) and 1-methylhistidine. Ornithine was the only metabolite exhibiting an increased level in the vitamin B6-deficient group. Vitamin B6 deficiency significantly attenuated the activity of heart tissue glutamate decarboxylase (GAD), although there was undetectable activity of aspartate decarboxylase (ADC), suggesting that the involvement of vitamin B6 in imidazole metabolite synthesis occurs partly through GABA production by regulating GAD rather than through a straightforward ß-alanine production pathway via ADC in the heart. Notably, vitamin B6 deficiency significantly attenuated citric acid cycle metabolite levels, suggesting cardiac energy metabolism impairment. This study provides a new link between vitamin B6 and cardiac functions, in which marginal vitamin B6 deficiency impairs imidazole and energy metabolism in heart. This newly revealed cardiac metabolic profile may reveal novel molecular targets or foodstuffs for CVD prevention.


Sujet(s)
Myocarde/métabolisme , Carence en vitamine B6/métabolisme , Animaux , Poids , Carboxy-lyases/métabolisme , Consommation alimentaire , Glutamate decarboxylase/métabolisme , Coeur/anatomie et histologie , Coeur/effets des médicaments et des substances chimiques , Mâle , Méthylhistidines/métabolisme , Taille d'organe , Ornithine/métabolisme , Rat Sprague-Dawley , Vitamine B6/sang , Vitamine B6/métabolisme , Vitamine B6/pharmacologie , Acide gamma-amino-butyrique/métabolisme
14.
J. physiol. biochem ; 74(4): 523-530, nov. 2018. graf, tab
Article de Anglais | IBECS | ID: ibc-179030

RÉSUMÉ

The aim was to determine the effects of enhanced availability of branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) on ammonia detoxification to glutamine (GLN) and protein metabolism in two types of skeletal muscle under hyperammonemic conditions. Isolated soleus (SOL, slow-twitch) and extensor digitorum longus (EDL, fast-twitch) muscles from the left leg of white rats were incubated in a medium with 1 mM ammonia (NH3 group), BCAAs at four times the concentration of the controls (BCAA group) or high levels of both ammonia and BCAA (NH3 + BCAA group). The muscles from the right leg were incubated in basal medium and served as paired controls. L-[1-14C]leucine was used to estimate protein synthesis and leucine oxidation, and 3-methylhistidine release was used to evaluate myofibrillar protein breakdown. We observed decreased protein synthesis and glutamate and alfa-ketoglutarate (alfa -KG) levels and increased leucine oxidation, GLN levels, and GLN release into medium in muscles in NH3 group. Increased leucine oxidation, release of branched-chain keto acids and GLN into incubation medium, and protein synthesis in EDL were observed in muscles in the BCAA group. The addition of BCAAs to medium eliminated the adverse effects of ammonia on protein synthesis and adjusted the decrease in alfa-KG found in the NH3 group. We conclude that (I) high levels of ammonia impair protein synthesis, activate BCAA catabolism, enhance GLN synthesis, and decrease glutamate and alfa-KG levels and (II) increased BCAA availability enhances GLN release from muscles and attenuates the adverse effects of ammonia on protein synthesis and decrease in alfa-KG


Sujet(s)
Animaux , Rats , Déficit en carbamoyl-phosphate synthase I/métabolisme , Fibres musculaires à contraction lente/métabolisme , Fibres musculaires à contraction rapide/métabolisme , Cycle citrique/effets des médicaments et des substances chimiques , Glutamine/métabolisme , Techniques in vitro , Cirrhose du foie/métabolisme , Méthylhistidines/métabolisme , Fibres musculaires à contraction lente , Fibres musculaires à contraction lente/enzymologie , Fibres musculaires à contraction rapide , Fibres musculaires à contraction rapide/enzymologie , Rat Wistar
15.
Org Lett ; 20(17): 5427-5430, 2018 09 07.
Article de Anglais | MEDLINE | ID: mdl-30141637

RÉSUMÉ

Ovothiols are thiolhistidine derivatives. The first step of ovothiol biosynthesis is OvoA-catalyzed oxidative coupling between histidine and cysteine. In this report, the remaining steps of ovothiol A biosynthesis were reconstituted in vitro. ETA_14770 (OvoB) was reported as a PLP-dependent sulfoxide lyase, responsible for mercaptohistidine production. OvoA was found to be a bifunctional enzyme, which mediates both oxidative C-S bond formation and methylation of mercaptohistidine to afford ovothiol A. Besides reconstituting the whole biosynthetic pathway, two unique features proposed in the literature were also examined: a potential cysteine-recycling mechanism of the C-S lyase (OvoB) and the selectivity of the π- N methyltransferase.


Sujet(s)
Lyases/métabolisme , Méthylhistidines/métabolisme , Methyltransferases/métabolisme , Lyases/composition chimique , Méthylhistidines/composition chimique , Methyltransferases/composition chimique , Modèles moléculaires , Conformation des protéines
16.
J Physiol Biochem ; 74(4): 523-530, 2018 Nov.
Article de Anglais | MEDLINE | ID: mdl-30058052

RÉSUMÉ

The aim was to determine the effects of enhanced availability of branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) on ammonia detoxification to glutamine (GLN) and protein metabolism in two types of skeletal muscle under hyperammonemic conditions. Isolated soleus (SOL, slow-twitch) and extensor digitorum longus (EDL, fast-twitch) muscles from the left leg of white rats were incubated in a medium with 1 mM ammonia (NH3 group), BCAAs at four times the concentration of the controls (BCAA group) or high levels of both ammonia and BCAA (NH3 + BCAA group). The muscles from the right leg were incubated in basal medium and served as paired controls. L-[1-14C]leucine was used to estimate protein synthesis and leucine oxidation, and 3-methylhistidine release was used to evaluate myofibrillar protein breakdown. We observed decreased protein synthesis and glutamate and α-ketoglutarate (α-KG) levels and increased leucine oxidation, GLN levels, and GLN release into medium in muscles in NH3 group. Increased leucine oxidation, release of branched-chain keto acids and GLN into incubation medium, and protein synthesis in EDL were observed in muscles in the BCAA group. The addition of BCAAs to medium eliminated the adverse effects of ammonia on protein synthesis and adjusted the decrease in α-KG found in the NH3 group. We conclude that (i) high levels of ammonia impair protein synthesis, activate BCAA catabolism, enhance GLN synthesis, and decrease glutamate and α-KG levels and (ii) increased BCAA availability enhances GLN release from muscles and attenuates the adverse effects of ammonia on protein synthesis and decrease in α-KG.


Sujet(s)
Acides aminés à chaine ramifiée/métabolisme , Hyperammoniémie/métabolisme , Fibres musculaires à contraction rapide/métabolisme , Fibres musculaires à contraction lente/métabolisme , Ammoniac/intoxication , Animaux , Radio-isotopes du carbone , Cycle citrique/effets des médicaments et des substances chimiques , Glutamine/agonistes , Glutamine/métabolisme , Hyperammoniémie/enzymologie , Hyperammoniémie/physiopathologie , Techniques in vitro , Acides cétoglutariques/métabolisme , Cirrhose du foie/étiologie , Cirrhose du foie/métabolisme , Méthylhistidines/métabolisme , Fibres musculaires à contraction rapide/effets des médicaments et des substances chimiques , Fibres musculaires à contraction rapide/enzymologie , Fibres musculaires à contraction lente/effets des médicaments et des substances chimiques , Fibres musculaires à contraction lente/enzymologie , Protéines du muscle/génétique , Protéines du muscle/métabolisme , Spécificité d'organe , Concentration osmolaire , Oxydoréduction , Biosynthèse des protéines/effets des médicaments et des substances chimiques , Protéolyse/effets des médicaments et des substances chimiques , Rat Wistar
17.
Nat Prod Rep ; 35(12): 1241-1250, 2018 12 12.
Article de Anglais | MEDLINE | ID: mdl-30052250

RÉSUMÉ

Covering: up to 2018 Ovothiols are sulfur-containing natural products biosynthesized by marine invertebrates, microalgae, and bacteria. These compounds are characterized by unique chemical properties suggestive of numerous cellular functions. For example, ovothiols may be cytoprotectants against oxidative stress, serve as building blocks of more complex structures and may act as molecular messengers for inter- and intracellular signaling. Detailed understanding of ovothiol physiological role in marine organisms may unearth novel concepts in cellular redox biochemistry and highlight the therapeutic potential of this antioxidant. The recent discovery of ovothiol biosynthetic genes has paved the way for a systematic investigation of ovothiol-modulated cellular processes. In this highlight we review the early research on ovothiol and we discuss key questions that may now be addressed using genome-based approaches. This highlight article provides an overview of recent progress towards elucidating the biosynthesis, function and potential application of ovothiols.


Sujet(s)
Organismes aquatiques/métabolisme , Invertébrés/métabolisme , Méthylhistidines/composition chimique , Méthylhistidines/métabolisme , Animaux , Voies de biosynthèse/génétique , Voies de biosynthèse/physiologie , Évolution moléculaire , Humains , Méthylhistidines/pharmacologie , Neuroprotecteurs/composition chimique , Neuroprotecteurs/pharmacologie
18.
Biochemistry ; 57(24): 3309-3325, 2018 06 19.
Article de Anglais | MEDLINE | ID: mdl-29589901

RÉSUMÉ

As one of the most abundant elements on earth, sulfur is part of many small molecular metabolites and is key to their biological activities. Over the past few decades, some general strategies have been discovered for the incorporation of sulfur into natural products. In this review, we summarize recent efforts in elucidating the biosynthetic details for two sulfur-containing metabolites, ergothioneine and ovothiol. Their biosyntheses involve an unprecedented trans-sulfur strategy, a combination of a mononuclear non-heme iron enzyme-catalyzed oxidative C-S bond formation reaction and a PLP enzyme-mediated C-S lyase reaction.


Sujet(s)
Produits biologiques/métabolisme , Ergothionéine/biosynthèse , Méthylhistidines/métabolisme , Soufre/métabolisme , Produits biologiques/composition chimique , Ergothionéine/composition chimique , Méthylhistidines/composition chimique , Conformation moléculaire , Soufre/composition chimique
19.
Br J Nutr ; 117(7): 911-922, 2017 Apr.
Article de Anglais | MEDLINE | ID: mdl-28446262

RÉSUMÉ

Branched-chain amino acids (BCAA) have been clearly demonstrated to have anabolic effects on muscle protein synthesis. However, little is known about their roles in the regulation of net AA fluxes across skeletal muscle in vivo. This study was aimed to investigate the effect and related mechanisms of dietary supplementation of BCAA on muscle net amino acid (AA) fluxes using the hindlimb flux model. In all fourteen 4-week-old barrows were fed reduced-protein diets with or without supplemental BCAA for 28 d. Pigs were implanted with carotid arterial, femoral arterial and venous catheters, and fed once hourly with intraarterial infusion of p-amino hippurate. Arterial and venous plasma and muscle samples were obtained for the measurement of AA, branched-chain α-keto acids (BCKA) and 3-methylhistidine (3-MH). Metabolomes of venous plasma were determined by HPLC-quadrupole time-of-flight-MS. BCAA-supplemented group showed elevated muscle net fluxes of total essential AA, non-essential AA and AA. As for individual AA, muscle net fluxes of each BCAA and their metabolites (alanine, glutamate and glutamine), along with those of histidine, methionine and several functional non-essential AA (glycine, proline and serine), were increased by BCAA supplementation. The elevated muscle net AA fluxes were associated with the increase in arterial and intramuscular concentrations of BCAA and venous metabolites including BCKA and free fatty acids, and were also related to the decrease in the intramuscular concentration of 3-MH. Correlation analysis indicated that muscle net AA fluxes are highly and positively correlated with arterial BCAA concentrations and muscle net BCKA production. In conclusion, supplementing BCAA to reduced-protein diet increases the arterial concentrations and intramuscular catabolism of BCAA, both of which would contribute to an increase of muscle net AA fluxes in young pigs.


Sujet(s)
Acides aminés à chaine ramifiée/administration et posologie , Anabolisants/administration et posologie , Régime pauvre en protéines/médecine vétérinaire , Développement musculaire , Protéines du muscle/biosynthèse , Muscles squelettiques/métabolisme , Régulation positive , Acides aminés/sang , Acides aminés/métabolisme , Acides aminés à chaine ramifiée/sang , Acides aminés à chaine ramifiée/métabolisme , Anabolisants/sang , Anabolisants/métabolisme , Animaux , Chine , Croisements génétiques , Régime pauvre en protéines/effets indésirables , Acide gras libre/sang , Acide gras libre/métabolisme , Membre pelvien , Techniques de dilution d'indicateur , Cétoacides/sang , Cétoacides/métabolisme , Mâle , Métabolomique/méthodes , Méthylhistidines/sang , Méthylhistidines/métabolisme , Muscles squelettiques/vascularisation , Muscles squelettiques/croissance et développement , Orchidectomie/médecine vétérinaire , Débit sanguin régional , Sus scrofa , Prise de poids
20.
PLoS One ; 12(3): e0174894, 2017.
Article de Anglais | MEDLINE | ID: mdl-28358856

RÉSUMÉ

Dexmedetomidine is generally used for sedaton in critically ill, it could shorten duration of mechanical ventilation, ICU stay and lower basic metabolism. However, the exact mechanism of these positive effects remains unkown. Here we investigated the hypothesis that dexmedetomidine could ameliorate muscle wasting in endotoxemic rats and whether it was related to hypothalamic neuropeptides alteration and inflammation. Fourty-eight adult male Sprague-Dawley rats were intraperitoneally injected with lipopolysaccharide (LPS) (5 mg/kg) or saline, followed by 50 µg/kg dexmedetomidine or saline administration via the femoral vein catheter (infusion at 5 µg·kg-1·hr-1). Twenty-four hours after injection, hypothalamus tissues and skeletal muscle were obtained. Muscle wasting was measured by the mRNA expression of two E3 ubiquitin ligases, muscle atrophy F-box (MAFbx) and muscle ring finger 1 (MuRF-1) as well as 3-methylhistidine (3-MH) and tyrosine release. Hypothalamic inflammatory markers and neuropeptides expression were also detected in all four groups. Results showed that LPS administration led to significant increase in hypothalamic inflammation together with muscle wasting. Increased hypothalamic neuropeptides, proopiomelanocortin (POMC), cocaine and amphetamine-related transcript (CART) and neuropeptides Y (NPY) and decreased agouti-related protein (AgRP) were also observed. Meanwhile dexmedetomidine administration ameliorated muscle wasting, hypothalamic inflammation and modulated the alteration of neuropeptides, POMC, CART and AgRP, in endotoxemic rats. In conclusion, dexmedetomidine could alleviate muscle wasting in endotoxemic rats, and it could also attenuate the alteration of hypothalamic neuropeptides and reduce hypothalamic inflammation.


Sujet(s)
Dexmédétomidine/usage thérapeutique , Endotoxémie/traitement médicamenteux , Hypothalamus/métabolisme , Inflammation/traitement médicamenteux , Muscles squelettiques/effets des médicaments et des substances chimiques , Muscles squelettiques/anatomopathologie , Neuropeptides/métabolisme , Protéine apparentée à Agouti/métabolisme , Animaux , Endotoxémie/métabolisme , Hypothalamus/effets des médicaments et des substances chimiques , Inflammation/métabolisme , Interleukine-1/métabolisme , Mâle , Méthylhistidines/métabolisme , Muscles squelettiques/métabolisme , Amyotrophie/traitement médicamenteux , Amyotrophie/métabolisme , Protéines de tissu nerveux/métabolisme , Neuropeptide Y/métabolisme , Pro-opiomélanocortine/métabolisme , Rats , Rat Sprague-Dawley , Facteur de nécrose tumorale alpha/métabolisme
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