Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 10.294
Filtrar
1.
Anticancer Res ; 39(10): 5427-5436, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31570437

RESUMO

BACKGROUND/AIM: Renal cell carcinoma (RCC) is one of the most common tumor diseases in adults, and new specific biomarkers are urgently needed to define diagnosis and prognosis of patients with RCC as well as monitor the outcome of therapeutic interventions. The enzyme nicotinamide N-methyltransferase (NNMT) is believed to represent such a marker molecule in RCC therapy. MATERIALS AND METHODS: NNMT expression was examined by western blotting in samples from patients with RCC and in RCC cell lines. Effects of NNMT on cell growth and metabolism were assessed using the Hoechst 33342 reagent assay and Vita-Orange cell viability assay. Incubation experiments were performed to study the influence of methionine and interleukin-6 (IL6) on expression of NNMT. RESULTS: In patient samples, NNMT was up-regulated depending on the stage of progression. Investigations in an RCC cell culture model showed that after modulation of NNMT expression, cellular metabolism, but not cell growth was affected. This regulatory function was also dependent on the presence of the NNMT precursor substrate methionine and IL6. CONCLUSION: The metabolism-regulatory activity of NNMT depends on the precursor substrate methionine and the presence of IL6. The function of methionine appears to be dependent on the stage of progression, since in individual RCC cell lines, opposing effects on metabolism were demonstrated. This, in turn, reflects the thoroughly complex situation in the clinic.


Assuntos
Carcinoma de Células Renais/metabolismo , Neoplasias Renais/metabolismo , Metionina/metabolismo , Nicotinamida N-Metiltransferase/metabolismo , Biomarcadores Tumorais/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/fisiologia , Progressão da Doença , Células HEK293 , Humanos , Interleucina-6/metabolismo , Prognóstico , Regulação para Cima/fisiologia
2.
Inorg Chem ; 58(20): 14085-14106, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31589413

RESUMO

Ligand-switch reactions at the heme iron are common in biological systems, but their mechanisms and the features of the polypeptide fold that support dual ligation are not well understood. In cytochrome c (cyt c), two low-stability loops (Ω-loop C and Ω-loop D) are connected by the heme propionate HP6. At alkaline pH, the native Met80 ligand from Ω-loop D switches to a Lys residue from the same loop. Deprotonation of an as yet unknown group triggers the alkaline transition. We have created the two cyt c variants T49V/K79G and T78V/K79G with altered connections of these two loops to HP6. Electronic absorption, NMR, and EPR studies demonstrate that at pH 7.4 ferric forms of these variants are Lys-ligated, whereas ferrous forms maintain the native Met80 ligation. Measurements of protein stability, cyclic voltammetry, pH-jump and gated electron-transfer kinetics have revealed that these Thr to Val substitutions greatly affect the alkaline transition in both ferric and ferrous proteins. The substitutions modify the stability of the Met-ligated species and reduction potentials of the heme iron. The kinetics of ligand-switch processes are also altered, and analyses of these effects implicate redox-dependent differences in metal-ligand interactions and the role of the protein dynamics, including cross-talk between the two Ω-loops. With the two destabilized variants, it is possible to map energy levels for the Met- and Lys-ligated species in both ferric and ferrous proteins and assess the role of the protein scaffold in redox-dependent preferences for these two ligands. The estimated shift in the heme iron reduction potential upon deprotonation of the "trigger" group is consistent with those associated with deprotonation of an HP, suggesting that HP6, on its own or as a part of a hydrogen-bonded cluster, is a likely "trigger" for the Met to Lys ligand switch.


Assuntos
Complexos de Coordenação/química , Citocromos c/química , Heme/química , Ferro/química , Metionina/química , Propionatos/química , Complexos de Coordenação/metabolismo , Citocromos c/genética , Citocromos c/metabolismo , Heme/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Ferro/metabolismo , Cinética , Ligantes , Metionina/metabolismo , Modelos Moleculares , Mutagênese Sítio-Dirigida , Propionatos/metabolismo
3.
Food Chem ; 298: 124952, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260994

RESUMO

The riboflavin-mediated photo-degradation of methionine in white wine has been related to onset of undesired light-struck taste. This research investigated the effects of different concentrations of riboflavin and methionine, hydrolysable tannins from various sources (nut galls, chestnut and oak woods) and sulfur dioxide on methionine degradation in a model wine exposed to light. Increased methionine concentration resulted in its increased degradation with the consequent formation of volatile sulfur compounds, namely methanethiol, dimethyl disulphide and dimethyl trisulphide. Tannins, especially nut gall tannin, were effective in limiting both methionine degradation and the production of volatile sulfur compounds. Sulfur dioxide enhanced the methionine degradation although the light-struck taste was not perceived when sulfur dioxide concentration was higher than 50 mg/L. In conclusion, the use of hydrolysable tannins can represent a promising tool for protecting white wine against the light-struck taste also limiting the use of sulfur dioxide.


Assuntos
Taninos Hidrolisáveis/química , Metionina/química , Riboflavina/química , Dióxido de Enxofre/química , Vinho , Dissulfetos/química , Luz , Metionina/metabolismo , Processos Fotoquímicos , Compostos de Sulfidrila/química , Paladar/efeitos dos fármacos , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/metabolismo , Vinho/análise
4.
J Sci Food Agric ; 99(14): 6582-6588, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31328268

RESUMO

BACKGROUND: This study was conducted to investigate effects of dietary zinc methionine (Zn-Met) supplementation on laying performance, zinc (Zn) status, intestinal morphology, and Zn transporters in laying hens compared with zinc sulfate (ZnSO4 ). A total of 384 Hyline Grey laying hens (38 weeks old) with similar performance (1.42 ± 0.07 kg) were randomly allotted to four dietary treatments and fed with a basal diet (control) or the basal diet supplemented with Zn, either as Zn-Met at 40 and 80 mg Zn/kilogram diet or as ZnSO4 at 80 mg Zn/kilogram diet, for 10 weeks. RESULTS: There was no difference in egg weight, egg production, feed intake, and feed conversation ratio among all groups (P > 0.05). Compared with the control, Zn contents were increased (P < 0.05) in the liver, duodenum, and jejunum of laying hens fed diets supplemented with different Zn sources. There was no difference (P > 0.05) in Zn contents in liver, duodenum, and jejunum between diets supplemented with Zn-Met or ZnSO4 at 80 mg Zn/kilogram diet. Compared with the control and the ZnSO4 group (80 mg Zn/kilogram diet), supplementation with Zn-Met of 80 mg Zn/kilogram diet increased (P < 0.05) villus height, villus area, and villus height/crypt depth ratio but reduced (P < 0.05) crypt depth in jejunum. Expression of metallothionein messenger RNA of jejunum in the group fed a diet containing Zn-Met (80 mg Zn/kilogram diet) was higher (P < 0.05) than that in the control. CONCLUSION: These results indicated that Zn-Met has positive effects on the Zn status of liver, duodenum, and jejunum, intestinal morphology, and metallothionein messenger RNA expression in jejunum of laying hens compared with ZnSO4 . © 2019 Society of Chemical Industry.


Assuntos
Proteínas de Transporte/genética , Galinhas/crescimento & desenvolvimento , Galinhas/metabolismo , Intestinos/crescimento & desenvolvimento , Metionina/análogos & derivados , Compostos Organometálicos/administração & dosagem , Zinco/metabolismo , Ração Animal/análise , Animais , Proteínas de Transporte/metabolismo , Galinhas/genética , Suplementos Nutricionais/análise , Ovos/análise , Feminino , Intestinos/efeitos dos fármacos , Metionina/administração & dosagem , Metionina/metabolismo , Compostos Organometálicos/metabolismo , Zinco/análise
5.
J Dairy Sci ; 102(9): 8305-8318, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31301838

RESUMO

Although choline requirements are unknown, enhanced postruminal supply may decrease liver triacylglycerol (TAG) storage and increase flux through the methionine cycle, helping cows during a negative energy balance (NEB). The objective was to investigate effects of postruminal choline supply during NEB on hepatic activity of betaine-homocysteine methyltransferase (BHMT), methionine synthase (MTR), methionine adenosyltransferase, transcription of enzymes, and metabolite concentrations in the methionine cycle. Ten primiparous rumen-cannulated Holstein cows (158 ± 24 d postpartum) were used in a replicated 5 × 5 Latin square design with 4-d treatment periods and 10 d of recovery (14 d/period). Treatments were unrestricted intake with abomasal infusion of water (A0), restricted intake (R; 60% of net energy for lactation requirements to induce NEB) with abomasal infusion of water (R0) or R plus abomasal infusion of 6.25, 12.5, or 25 g/d of choline ion. Liver tissue was collected on d 5 after the infusions ended, blood on d 1 to 5, and milk on d 1 to 4. Statistical contrasts were A0 versus R0 (CONT1) and tests of linear (L), quadratic (Q), and cubic (C) effects of choline dose. Plasma choline increased with R (CONT1) and choline (L). Although R decreased milk yield (CONT1), choline increased milk yield and liver phosphatidylcholine (PC), but decreased TAG (L). No differences were observed in plasma PC or very-low-density lipoprotein concentrations with R or choline. Activity and mRNA abundance of BHMT were greater with R (CONT1) and increased with choline (L). Although activity of MTR was lower with R (CONT1), it tended to increase with choline (L). No effect of R was detected for activity of methionine adenosyltransferase, but it changed cubically across dose of choline. Those responses were associated with linear increases in the concentrations of liver tissue (+13%) and plasma methionine concentrations. The mRNA abundance of CPT1A, SLC22A5, APOA5, and APOB, genes associated with fatty acid oxidation and lipoprotein metabolism, was upregulated by choline (Q). Overall, enhanced supply of choline during NEB increases hepatic activity of BHMT and MTR to regenerate methionine and PC, partly to help clear TAG. The relevance of these effects during the periparturient period merits further research.


Assuntos
5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/metabolismo , Betaína-Homocisteína S-Metiltransferase/metabolismo , Bovinos/metabolismo , Colina/administração & dosagem , Metabolismo Energético/efeitos dos fármacos , Fígado/metabolismo , Metionina/metabolismo , Abomaso/efeitos dos fármacos , Animais , Betaína-Homocisteína S-Metiltransferase/genética , Colina/sangue , Ácidos Graxos/metabolismo , Feminino , Lactação/efeitos dos fármacos , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipoproteínas/metabolismo , Fígado/efeitos dos fármacos , Fígado/enzimologia , Metionina/sangue , Oxirredução , Parto/metabolismo , Gravidez , RNA Mensageiro/análise
6.
Enzyme Microb Technol ; 129: 109355, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31307578

RESUMO

S-adenosylmethionine synthetase (MAT) catalyzes the synthesis of S-adenosylmethionine (SAM) from ATP and L-methionine. SAM is the major methyl donor for more than 100 transmethylation reactions. It is also a common cosubstrate involved in transsulfuration and aminopropylation. However, product inhibition largely restrains the activity of MAT and limits the enzymatic synthesis of SAM. In this research, the product inhibition of MAT from Escherichia coli was reduced via semi-rational modification. A triple variant (Variant III, I303 V/I65 V/L186 V) showed a 42-fold increase in Ki,ATP and a 2.08-fold increase in specific activity when compared to wild-type MAT. Its Ki,ATP was 0.42 mM and specific acitivity was 3.78 ±0.19 U/mg. Increased Ki,ATP means reduced product inhibition which enhances SAM accumulation. The SAM produced by Variant III could reach to 3.27 mM while SAM produced by wild-type MAT was 1.62 mM in the presence of 10 mM substrates. When the residue in 104th of Variant III was further optimized by site-saturated mutagenesis, the specific activity of Variant IV (I303 V/I65 V/L186 V/N104 K) reached to 6.02 ±0.22 U/mg at 37 °C, though the SAM concentration decreased to 2.68 mM with 10 mM substrates. Analysis of protein 3D structure suggests that changes in hydrogen bonds or other ligand interactions around active site may account for the variety of product inhibition and enzyme activity. The Variant III and Variant IV with reduced inhibition and improved enzyme activity in the study would be more suitable candidates for SAM production in the future.


Assuntos
Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimologia , Metionina Adenosiltransferase/química , Metionina Adenosiltransferase/metabolismo , Catálise , Domínio Catalítico , Escherichia coli/química , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Cinética , Metionina/metabolismo , Metionina Adenosiltransferase/genética , Modelos Moleculares , S-Adenosilmetionina/metabolismo
7.
Analyst ; 144(13): 3988-3998, 2019 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-31169288

RESUMO

Methylation of components involved in one-carbon metabolism is extremely important in cancer; comprehensive studies on methylation are essential and may provide us with a better understanding of tumorigenesis, and lead to the discovery of potential biomarkers. Here, we present an improved methodology for methylated metabolite profiling and its relative quantification in breast cancer cell lines by isotope dilution mass spectrometry based on 13CD3-methionine metabolic labeling using ultra-high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UPLC-HRMS/MS). First, all the methylated metabolites related to methionine were first screened and profiled by introducing 13CD3-methionine as the only medium into breast cancer cell growth cultures for both cellular polar metabolites and lipids. In total, we successfully found 20 labeled methylated metabolites and most of them were identified, some of which have not been reported before. We also developed a relative quantification method for all identified methylated metabolites based on isotope dilution mass spectrometry assays. Finally, the developed method was used for different breast cancer cells and mammary epithelial cells. Most methylated metabolites were disrupted in cancer cells. 1-Methyl-nicotinamide was decreased significantly, while trimethylglycine-glutamic acid-lysine and trimethyl-lysine were increased more than five times. This method offers a new insight into the methylation process, with several key pathways and important new metabolites being identified. Further investigation with biological assays should help to reveal the overall methylation metabolic network.


Assuntos
Metaboloma , Metabolômica/métodos , Metionina/metabolismo , Isótopos de Carbono/química , Linhagem Celular Tumoral , Cromatografia Líquida de Alta Pressão , Deutério/química , Humanos , Marcação por Isótopo , Metionina/química , Metilação , Espectrometria de Massas em Tandem
8.
Nat Med ; 25(5): 825-837, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31061538

RESUMO

Understanding cellular metabolism holds immense potential for developing new classes of therapeutics that target metabolic pathways in cancer. Metabolic pathways are altered in bulk neoplastic cells in comparison to normal tissues. However, carcinoma cells within tumors are heterogeneous, and tumor-initiating cells (TICs) are important therapeutic targets that have remained metabolically uncharacterized. To understand their metabolic alterations, we performed metabolomics and metabolite tracing analyses, which revealed that TICs have highly elevated methionine cycle activity and transmethylation rates that are driven by MAT2A. High methionine cycle activity causes methionine consumption to far outstrip its regeneration, leading to addiction to exogenous methionine. Pharmacological inhibition of the methionine cycle, even transiently, is sufficient to cripple the tumor-initiating capability of these cells. Methionine cycle flux specifically influences the epigenetic state of cancer cells and drives tumor initiation. Methionine cycle enzymes are also enriched in other tumor types, and MAT2A expression impinges upon the sensitivity of certain cancer cells to therapeutic inhibition.


Assuntos
Metionina/metabolismo , Células-Tronco Neoplásicas/metabolismo , Animais , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Diferenciação Celular , Linhagem Celular Tumoral , Feminino , Técnicas de Silenciamento de Genes , Glicina Desidrogenase (Descarboxilante)/antagonistas & inibidores , Glicina Desidrogenase (Descarboxilante)/genética , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Masculino , Redes e Vias Metabólicas , Metabolômica , Metionina Adenosiltransferase/antagonistas & inibidores , Metionina Adenosiltransferase/metabolismo , Camundongos , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/patologia , S-Adenosilmetionina/metabolismo
9.
Plant Sci ; 283: 195-201, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31128689

RESUMO

Methionine and threonine are two essential amino acids whose low levels limit the nutritional quality of seeds. The current objective was to define factors that regulate and might increase their levels in seeds. Feeding experiments carried out on receptacles of developing tobacco (Nicotiana tabacum) capsules showed that 1 mM of S-methylmethionine increased the level of methionine to contents similar to 2.5 mM of homoserine, an intermediate metabolite of the aspartate family of amino acids. The latter also increased the level of threonine. Based on these findings, we generated tobacco seeds that expressed a combination of bacterial feedback-insensitive aspartate kinase (bAK), which was previously reported to have a high level of threonine/methionine, and feedback-insensitive cystathionine γ-synthase (CGS), the regulatory enzyme of the methionine biosynthesis pathway. Plants expressing this latter gene previously showed having higher levels of methionine. The results of total amino acids analysis showed that the level of threonine was highest in the bAK line, which has moderate levels of methionine and lysine, while the highest level of methionine was found in seeds expressing both heterologous genes. The results suggest that the level of threonine in tobacco seeds is limited by the substrate, while that of methionine is limited also by the activity of CGS.


Assuntos
Carbono-Oxigênio Liases/metabolismo , Metionina/metabolismo , Proteínas de Plantas/metabolismo , Sementes/metabolismo , Treonina/metabolismo , Tabaco/metabolismo , Aminoácidos/metabolismo , Homosserina/metabolismo , Redes e Vias Metabólicas , Plantas Geneticamente Modificadas , Sementes/enzimologia , Tabaco/enzimologia
10.
J Therm Biol ; 82: 234-241, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31128654

RESUMO

The gilthead sea bream (Sparus aurata, L.) is very sensitive to low temperatures, which induce fasting and reduced growth performances. There is a strong interest in understanding the impact of cold on fish metabolism to foster the development and optimization of specific aquaculture practices for the winter period. In this study, an 8 week feeding trial was carried out on gilthead sea bream juveniles reared in a Recirculated Aquaculture System (RAS) by applying a temperature ramp in two phases of four weeks each: a cooling phase from 18 °C to 11 °C and a cold maintenance phase at 11 °C. Liver protein profiles were evaluated with a shotgun proteomics workflow based on filter-aided sample preparation (FASP) and liquid chromatography-mass spectrometry (LC-ESI-Q-TOF MS/MS) followed by label-free differential analysis. Along the whole trial, sea breams underwent several changes in liver protein abundance. These occurred mostly during the cooling phase when catabolic processes were mainly observed, including protein and lipid degradation, together with a reduction in protein synthesis and amino acid metabolism. A decrease in protein mediators of oxidative stress protection was also seen. Liver protein profiles changed less during cold maintenance, but pathways such as the methionine cycle and sugar metabolism were significantly affected. These results provide novel insights on the dynamics and extent of the metabolic shift occurring in sea bream liver with decreasing water temperature, supporting future studies on temperature-adapted feed formulations. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD011059.


Assuntos
Resposta ao Choque Frio , Proteínas de Peixes/metabolismo , Dourada/fisiologia , Animais , Fígado/metabolismo , Redes e Vias Metabólicas , Metionina/metabolismo , Proteômica , Espectrometria de Massas em Tandem
11.
Am J Chin Med ; 47(4): 787-801, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31091973

RESUMO

American ginseng and Asian ginseng, which occupy prominent positions in the list of best-selling natural products in the West and East, are suitable for different indications in the traditional pharmacological uses. Currently, the effects of American ginseng and Asian ginseng in the protection against metabolic dysfunction and the differences between them are still unknown. Herein, an untargeted metabolomics based on liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) was determined. The serum metabolomics and dynamic feces metabolomics revealed significant metabolic distinction between American ginseng and Asian ginseng in diet-induced obese (DIO) mice. The results show that American ginseng and Asian ginseng alleviate glucose and lipid metabolism disorder in DIO mice. A total of 45 differential metabolites were confirmed between the drug-naïve and American ginseng group, and 32 metabolites were confirmed between the drug-naïve and Asian ginseng group. Metabolic pathways analysis shows that these two ginsengs treatment dynamic rectifies metabolic disorder in DIO mice mainly via regulating linoleic acids metabolism, cysteine and methionine metabolism and biosynthesis of unsaturated fatty acid. Moreover, American ginseng's specific function in monitoring the carnitines and taurine/hypotaurine metabolism might make it more effective in meliorating lipids metabolism disorder than Asian ginseng.


Assuntos
Dieta Hiperlipídica/efeitos adversos , Glucose/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolômica/métodos , Obesidade/etiologia , Obesidade/metabolismo , Panax/química , Panax/classificação , Extratos Vegetais/farmacologia , Animais , Carnitina/metabolismo , Cromatografia Líquida , Cisteína/metabolismo , Ácidos Graxos/biossíntese , Ácido Linoleico/metabolismo , Masculino , Espectrometria de Massas , Metionina/metabolismo , Camundongos Endogâmicos C57BL , Obesidade/tratamento farmacológico , Fitoterapia , Extratos Vegetais/uso terapêutico , Taurina/metabolismo
12.
Scand J Immunol ; 90(3): e12791, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31132306

RESUMO

The epoxyeicosatrienoic acids (EETs) are products of cytochrome P450 epoxygenases and have recently been found to have an anti-inflammatory activity. However, the role of EETs in non-alcoholic steatohepatitis has not been fully understood. In this study, we investigated the protective role of EETs in methionine-choline-deficient (MCD) diet-induced non-alcoholic steatohepatitis (NASH) in mice and the potential mechanisms. We used 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl)urea(TPPU), a soluble epoxide hydrolase inhibitor, to increase the endogenous EET level in mice. Upon TPPU treatment, the liver steatosis and inflammatory damage were significantly ameliorated in mice with steatohepatitis, paralleled by the downregulation of pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6) as well as chemokines (CXCL1, MCP-1). Compared with untreated NASH mice, mRNA levels of sterol regulatory element binding protein 1c (SREBP1c) and inflammation relevant adhesion molecules (ICAM-1, VCAM-1) were downregulated, whereas mRNA level of peroxisome proliferator-activated receptor α(PPAR-α) was elevated in TPPU-treated mice. In vitro, 11,12-EET treatment remarkably attenuated free fatty acid (FFA)-induced inflammation in HepG2 and THP-1 cells. Further, 11,12-EET inhibited the activation of NF-κB signalling pathway in macrophages from mice with steatohepatitis. Collectively, these results suggest that EETs play a protective role and alleviate the MCD diet-induced steatohepatitis in mice mainly by downregulating activation of NF-κB pathway in macrophages.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Dieta/efeitos adversos , Metionina/metabolismo , Hepatopatia Gordurosa não Alcoólica/induzido quimicamente , Hepatopatia Gordurosa não Alcoólica/metabolismo , Animais , Linhagem Celular , Linhagem Celular Tumoral , Quimiocinas/metabolismo , Colina/metabolismo , Citocinas/metabolismo , Regulação para Baixo/efeitos dos fármacos , Células Hep G2 , Humanos , Inflamação/metabolismo , Molécula 1 de Adesão Intercelular/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , NF-kappa B/metabolismo , PPAR alfa/metabolismo , Compostos de Fenilureia/farmacologia , Piperidinas/farmacologia , RNA Mensageiro/metabolismo , Transdução de Sinais/efeitos dos fármacos , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Células THP-1 , Molécula 1 de Adesão de Célula Vascular/metabolismo
13.
Wei Sheng Yan Jiu ; 48(3): 463-467, 2019 May.
Artigo em Chinês | MEDLINE | ID: mdl-31133135

RESUMO

OBJECTIVE: To investigate the effects of methionine on the activity of cystathionine-ß-synthase. METHODS: A total of 56 male rats of the Wistar were randomly divided into 7 groups: 10% casein(10 C) group, 40% casein(40 C) group, 10 C+0.75% L-methionine(10 CM) group, 10 C+amino acid mixture(10 CAA) group, 10 CAA-methionine(10 CAA-Met) group, 10 C+ essential amino acid(10 C+EAA) group, and 10 C+ non-essential amino acid(10 C+NEAA) group, with 8 rats in each group for 10 days. RESULTS: The plasma homocysteine concentration significantly increased from(17.1±0.3)µmol/L to(50.7±4.8)µmol/L and(40.5±3.9)µmol/L in rats fed 10 CM and 10 C+EAA diets(P<0.01). Supplementation with methionine induced hyperhomocysteinemia. Compared to 10 C, the activity of hepatic cystathionine-ß-synthase(CBS) were significantly increased in the experimental group except for 10 CM(P<0.05). The activity of hepatic CBS was the largest increases in diets with 40 C and the smallest increases in 10 C+NEAA. The activity of hepatic betaine-homocysteine S-methyltransferase(BHMT) were increased in the experimental group except for 10 CAA-Met and 10 C+NEAA(P<0.05). CONCLUSION: The increased CBS activity induced by high protein diets is determined by high amino acid intake rather than methionine supplemention.


Assuntos
Metionina/metabolismo , Animais , Betaína-Homocisteína S-Metiltransferase , Cistationina , Cistationina beta-Sintase , Homocisteína , Fígado , Masculino , Ratos , Ratos Wistar
14.
J Dairy Sci ; 102(9): 8319-8331, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31056334

RESUMO

Although choline requirements for cows are unknown, enhanced postruminal supply may decrease liver triacylglycerol and increase flux through the Met cycle to improve immunometabolic status during a negative nutrient balance (NNB). Our objectives were to investigate the effects of postruminal choline supply during a feed restriction-induced NNB on (1) hepatic activity cystathionine ß-synthase and transcription of enzymes in the transsulfuration pathway and Met cycle; (2) hepatic metabolites in the Met cycle and the transsulfuration pathway, bile acids, and energy metabolism; and 3) plasma biomarkers of liver function, inflammation, and oxidative stress. Ten primiparous rumen-cannulated Holstein cows (158 ± 24 d postpartum) were used in a replicated 5 × 5 Latin square design with 4-d treatment periods and 10 d of recovery (14 d/period). Treatments were unrestricted intake with abomasal infusion of water, restricted intake (R; 60% of net energy for lactation requirements) with abomasal infusion of water, or R plus abomasal infusion of 6.25, 12.5, or 25 g/d choline ion. Liver tissue was collected on d 5 after infusions ended, and blood was collected on d 1, 3, and 5. Statistical contrasts were A0 versus R0 (CONT1), R versus the average of choline doses (CONT2), and tests of linear and quadratic effects of choline dose. Activity of cystathionine ß-synthase was lower with R (CONT1) and decreased linearly with choline. Hepatic glutathione was not different with R or choline, but taurine tended to be greater with choline (CONT2). Betaine and carnitine were greater with R (CONT1) and further increased with choline (CONT2). Concentrations of NAD+ were greater with choline (CONT2). Cholic and glycol-chenodeoxycholic acids were decreased by R and choline, while taurocholic and tauro-chenodeoxycholic acids were not altered. Plasma aspartate aminotransferase and bilirubin were greater with R (CONT1) but decreased with choline (CONT2). Paraoxonase was lower with R and increased with choline (CONT2). Data suggest that enhanced supply of choline during NNB decreases entry of homocysteine to the transsulfuration pathway, potentially favoring remethylation to Met by acquiring a methyl group from betaine. As such, Met may provide methyl groups for synthesis of carnitine. Along with production data indicating that 12.5 g/d choline ion improved milk yield and liver fatty acid metabolism during NNB, the changes in blood biomarkers also suggest a beneficial effect of choline supply on liver function and oxidative stress.


Assuntos
Bovinos/fisiologia , Colina/administração & dosagem , Cistationina beta-Sintase/metabolismo , Fígado/fisiologia , Metionina/metabolismo , Compostos de Enxofre/metabolismo , Abomaso/metabolismo , Animais , Betaína/metabolismo , Dieta/veterinária , Metabolismo Energético , Feminino , Humanos , Lactação/efeitos dos fármacos , Metabolismo dos Lipídeos , Fígado/efeitos dos fármacos , Leite/metabolismo , Necessidades Nutricionais , Estado Nutricional/fisiologia , Estresse Oxidativo/efeitos dos fármacos , Período Periparto , Período Pós-Parto , Gravidez , Triglicerídeos/metabolismo
15.
Int J Med Microbiol ; 309(5): 288-298, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31126750

RESUMO

N-terminal methionine excision (NME) is a proteolytic pathway that cleaves the N-termini of proteins, a process that influences where proteins localise in the cell and their turnover rates. In bacteria, protein biosynthesis is initiated by formylated methionine start tRNA (fMet-tRNAfMet). The formyl group is attached by formyltransferase (FMT) and is subsequently removed by peptide deformylase (PDF) in most but not all proteins. Methionine aminopeptidase then cleaves deformylated methionine to complete the process. Components of NME, particularly PDF, are promising therapeutic targets for bacterial pathogens. In Mycoplasma hyopneumoniae, a genome-reduced, major respiratory pathogen of swine, pdf and fmt are absent from its genome. Our bioinformatic analysis uncovered additional enzymes involved in formylated N-terminal methionine (fnMet) processing missing in fourteen mycoplasma species, including M. hyopneumoniae but not in Mycoplasma pneumoniae, a major respiratory pathogen of humans. Consistent with our bioinformatic studies, an analysis of in-house tryptic peptide libraries confirmed the absence of fnMet in M. hyopneumoniae proteins but, as expected fnMet peptides were detected in the proteome of M. pneumoniae. Additionally, computational molecular modelling of M. hyopneumoniae translation initiation factors reveal structural and sequence differences in areas known to interact with fMet-tRNAfMet. Our data suggests that some mycoplasmas have evolved a translation process that does not require fnMet.


Assuntos
Metionina/metabolismo , Mycoplasma hyopneumoniae/genética , Iniciação Traducional da Cadeia Peptídica , Biossíntese de Proteínas , Biologia Computacional , Modelos Moleculares , Mycoplasma hyopneumoniae/enzimologia , Peptídeo Hidrolases/genética , Biblioteca de Peptídeos , Proteoma
16.
Prep Biochem Biotechnol ; 49(6): 567-577, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30929621

RESUMO

Polyhydroxyalkanoates (PHAs) are intracellular carbon and energy storage reserve material stored by gram-negative bacteria under nutrient limitation. PHAs are best alternative biodegradable plastics (bio-plastics) due to their resemblance to conventional synthetic plastic. The present study investigated the synergistic effect of nutritional supplements (amino acid and vitamin) on the PHA production by Alcaligenes sp. NCIM 5085 utilizing a sugar refinery waste (cane molasses) under submerged fermentation process. Initially, the effect of individual factor on PHA yield was studied by supplementing amino acids (cysteine, isoleucine, and methionine), vitamin (thiamin), and cane molasses at varying concentration in the production medium. Further, the cultivation medium was optimized by varying the levels of cane molasses, methionine and thiamin using response surface methodology to enhance the PHA yield. The maximum PHA yield of 70.89% was obtained under the optimized condition, which was then scaled up on 7.5 L-bioreactor. Batch cultivation in 7.5 L-bioreactor under the optimized condition gave a maximum PHA yield and productivity of 79.26% and 0.312 gL-1 h-1, respectively. The PHA produced was subsequently characterized as PHB by FTIR. PHB extracted was of relatively high molecular weight and crystallinity index. DSC analysis gave Tg, Tm, and Xc of 4.2, 179 °C and 66%, respectively. TGA analysis showed thermal stability with maximized degradation occurring at 302 °C, which is above the melting temperature (179 °C) of the purified polymer. The extracted polymer, therefore, possessed desirable material properties to be used in food packaging.


Assuntos
Aminoácidos/metabolismo , Poli-Hidroxialcanoatos/biossíntese , Tiamina/metabolismo , Alcaligenes/metabolismo , Reatores Biológicos , Cisteína/metabolismo , Fermentação , Embalagem de Alimentos , Resíduos Industriais/prevenção & controle , Isoleucina/metabolismo , Metionina/metabolismo , Melaço , Peso Molecular , Poli-Hidroxialcanoatos/química , Temperatura de Transição , Gerenciamento de Resíduos/métodos
17.
J Sci Food Agric ; 99(10): 4849-4862, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31001831

RESUMO

BACKGROUND: Methionine is an essential sulfur-containing amino acid. To elucidate the influence of l-methionine on activation of the nuclear factor erythroid 2-related factor 2-antioxidant responsive element (Nrf2-ARE) antioxidant pathway to stimulate the endogenous antioxidant activity for depressing reactive oxygen species (ROS)-derived oxidative stress, male Wistar rats were orally administered l-methionine daily for 14 days. RESULTS: With the intake of l-methionine, Nrf2 was activated by l-methionine through depressing Keap1 and Cul3, resulting in upregulation of ARE-driven antioxidant expression (glutamate cysteine ligase catalytic subunit, glutamate cysteine ligase modulatory subunit, glutathione synthase (GS), catalase (CAT), superoxide dismutase (SOD), heme oxygenase 1, NAD(P)H:quinone oxidoreductase 1, glutathione reductase (GR), glutathione S-transferase (GST), glutathione peroxidase (GPx)) with increasing l-methionine availability. Upon activation of Nrf2, glutathione synthesis was increased through upregulated expression of methionine adenosyltransferase, S-adenosylhomocysteine hydrolase, cystathionine ß-synthase, cystathionine γ-lyse, glutamate cysteine ligase (GCL) and GS, while hepatic expressions of methionine sulfoxide reductases (MsrA, MsrB2, MsrB3) and hepatic enzyme activities (CAT, SOD, GCL, GR, GST, GPx) were uniformly stimulated with increasing consumption of l-methionine. As a result, hepatic content of ROS and MDA were effectively reduced by l-methionine intake. CONCLUSION: The present study demonstrates that methionine availability plays a critical role in activation of the Nrf2-ARE pathway to induce an endogenous antioxidant response for depressing ROS-derived oxidative stress, which is primarily attributed to the stimulation of methionine sulfoxide reductase expression and glutathione synthesis. © 2019 Society of Chemical Industry.


Assuntos
Antioxidantes/metabolismo , Metionina/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo , Ratos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Animais , Glutationa , Glutationa Peroxidase/genética , Glutationa Peroxidase/metabolismo , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fígado/metabolismo , Masculino , Fator 2 Relacionado a NF-E2/genética , Ratos/genética , Ratos/crescimento & desenvolvimento , Ratos Wistar
18.
Plant Sci ; 280: 340-347, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30824013

RESUMO

The methionine-rich seed storage proteins of maize have been expressed in transgenic plants as a means to improve the overall sulfur amino acid content of seed. Previous attempts to increase the sulfur amino acid content of soybean seeds by this approach has met with limited success. It has been shown co-expression of different class of zeins can result in their stable accumulation in transgenic plants. In this study, conventional crosses between transgenic plants individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein were made to obtain plants that simultaneously express both the δ-zein and γ-zein. Transmission electron microscopic observation of thin-sections of transgenic soybean seeds revealed that the zeins accumulated in ER-derived protein bodies (PBs) which were found sparsely scattered in cytoplasm. The size of these PBs varied from 0.2 to 0.6 µm in soybean plants individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein. In contrast, soybeans co-expressing the 18 kDa δ-zein and 27 kDa γ-zein the PBs was 3-4 times larger. Electron microscopic observation also revealed the sequestration of PBs inside the vacuoles where they could be subjected to degradation by vacuolar proteases. Amino acid analysis of transgenic soybean individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein revealed only a minimal increase in the overall methionine content compared to the wild-type. In contrast, plants co-expressing 18 kDa δ-zein and 27 kDa γ-zein showed a significant increase (27%) in the methionine content compared to the control seeds.


Assuntos
Aminoácidos Sulfúricos/metabolismo , Metionina/metabolismo , Soja/metabolismo , Zea mays/genética , Zeína/metabolismo , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/ultraestrutura , Microscopia Eletrônica de Transmissão , Plantas Geneticamente Modificadas , Sementes/genética , Sementes/metabolismo , Sementes/ultraestrutura , Soja/genética , Soja/ultraestrutura , Vacúolos/metabolismo , Vacúolos/ultraestrutura , Zeína/genética
19.
Emerg Microbes Infect ; 8(1): 248-261, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30866779

RESUMO

p-Aminosalicylic acid (PAS) is an important second-line antibiotic for treating multidrug-resistant tuberculosis (MDR-TB). Due to gastrointestinal disturbance and intolerance, its potent and efficacy in the treatment of extensively drug-resistant (XDR)-TB commonly are poor. Thus, it is important to reveal the mechanism of susceptibility and resistance of Mycobacterium tuberculosis (Mtb) to this drug. Herein, we screened and established PAS-resistant (PASr) folC mutated and un-mutated Mtb strains, then utilized a multi-omics (genome, proteome, and metabolome) analysis to better characterize the mechanisms of PAS resistance in Mtb. Interestingly, we found that promotion of SAM-dependent methyltransferases and suppression of PAS uptake via inhibiting some drug transport associated membrane proteins were two key pathways for the folC mutated strain evolving into the PASr Mtb strain. However, the folC un-mutated strain was resistant to PAS via uptake of exogenous methionine, mitigating the role of inhibitors, and promoting DfrA, ThyA and FolC expression. Beyond these findings, we also found PAS resistance in Mtb might be associated with the increasing phenylalanine metabolism pathway. Collectively, our findings uncovered the differences of resistant mechanism between folC mutated and un-mutated Mtb strains resistant to PAS using multi-omics analysis and targeting modulators to these pathways may be effective for treatment of PASr Mtb strains.


Assuntos
Biologia Computacional/métodos , Farmacorresistência Bacteriana , Mutação , Mycobacterium tuberculosis/efeitos dos fármacos , Peptídeo Sintases/genética , Ácido Aminossalicílico/farmacologia , Proteínas de Bactérias/genética , Redes e Vias Metabólicas , Metabolômica , Metionina/metabolismo , Testes de Sensibilidade Microbiana , Mycobacterium tuberculosis/genética , Fenilalanina/metabolismo , Proteômica , Sequenciamento Completo do Genoma
20.
BMB Rep ; 52(3): 163-164, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30885288

RESUMO

The ribosomal synthesis of proteins in the eukaryotic cytosol has always been thought to start from the unformylated N-terminal (Nt) methionine (Met). In contrast, in virtually all nascent proteins in bacteria and eukaryotic organelles, such as mitochondria and chloroplasts, Nt-formyl-methionine (fMet) is the first building block of ribosomal synthesis. Through extensive approaches, including mass spectrometric analyses of the N-termini of proteins and molecular genetic techniques with an affinity-purified antibody for Nt-formylation, we investigated whether Nt-formylated proteins could also be produced and have their own metabolic fate in the cytosol of a eukaryote, such as yeast Saccharomyces cerevisiae. We discovered that Nt-formylated proteins could be generated in the cytosol by yeast mitochondrial formyltransferase (Fmt1). These Nt-formylated proteins were massively upregulated in the stationary phase or upon starvation for specific amino acids and were crucial for the adaptation to specific stresses. The stress-activated kinase Gcn2 was strictly required for the upregulation of Nt-formylated proteins by regulating the activity of Fmt1 and its retention in the cytosol. We also found that the Nt-fMet residues of Nt-formylated proteins could be distinct N-terminal degradation signals, termed fMet/N-degrons, and that Psh1 E3 ubiquitin ligase mediated the selective destruction of Nt-formylated proteins as the recognition component of a novel eukaryotic fMet/N-end rule pathway, termed fMet/N-recognin. [BMB Reports 2019; 52(3): 163-164].


Assuntos
Hidroximetil e Formil Transferases/fisiologia , Biossíntese de Proteínas/fisiologia , Aminoácidos/metabolismo , Citosol/metabolismo , Células Eucarióticas/metabolismo , Hidroximetil e Formil Transferases/metabolismo , Metionina/metabolismo , Mitocôndrias/metabolismo , Proteínas/metabolismo , Proteólise , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Regulação para Cima
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA