Elucidation of an anaerobic pathway for metabolism of L-carnitine-derived γ-butyrobetaine to trimethylamine in human gut bacteria
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PROVIDER: PRJNA698819 | ENA |
REPOSITORIES: ENA
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Project description:Trimethylamine (TMA) is an important gut microbial metabolite strongly associated with human disease. There are prominent gaps in our understanding of how TMA is produced from the essential dietary nutrient L-carnitine, particularly in the anoxic environment of the human gut where oxygen-dependent L-carnitine-metabolizing enzymes are likely inactive. Here, we elucidate the chemical and genetic basis for anaerobic TMA generation from the L-carnitine-derived metabolite γ-butyrobetaine (γbb) by the human gut bacterium Emergencia timonensis. We identify a set of genes upregulated by γbb and demonstrate that the enzymes encoded by the induced γbb utilization (bbu) gene cluster convert γbb to TMA. The key TMA-generating step is catalyzed by a previously unknown type of TMA-lyase enzyme that utilizes a flavin cofactor to catalyze a redox neutral transformation. We identify additional cultured and uncultured host-associated bacteria that possess the bbu gene cluster, providing insights into the distribution of anaerobic γbb metabolism. Lastly, we present genetic, transcriptional, and metabolomic evidence that confirms the relevance of this metabolic pathway in the human gut microbiota. These analyses indicate that the anaerobic pathway is a more substantial contributor to TMA generation from L-carnitine in the human gut than the previously proposed aerobic pathway. The discovery and characterization of the bbu pathway provides the critical missing link in anaerobic metabolism of L-carnitine to TMA, enabling investigation into the connection between this microbial function and human disease.
2021-02-03 | GSE165976 | GEO
Project description: Not available
| S-EPMC8364193 | biostudies-literature
Project description:Despite this large body of evidence from clinical studies that an improvement of carnitine status has beneficial effects on metabolic health, serious safety concerns with carnitine supplementation have been raised based on the recent observation that longterm carnitine supplementation (from weaning to 5 mo of age) in a transgenic mouse model of atherosclerosis (Apoe-/- mice) promotes atherosclerosis through gut microbiota-dependent formation of trimethylamine (TMA) and subsequent hepatic conversion into proatherogenic TMA-N-oxide (TMAO) (Koeth et al., 2013). In addition, Lu et al. (2017) found that carnitine supplementation to normal mice for 3 mo induces oxidative stress, liver inflammation, liver lipid accumulation and even liver damage as well as hypercholesterinemia. However, it has to be mentioned that the carnitine dose administered to the mice in the abovementioned studies was extremely high. In order to address whether safety concerns are founded under conditions of longterm supplementation of a carnitine dose used in clinical trials, the present study aimed to investigate the effect of almost lifelong daily administration of a carnitine-supplemented diet (1 g/kg diet) to mice from weaning to 18 mo of age. Considering a body weight of 50 g for an adult mice and a daily feed intake of 5 g, the daily intake of this diet results in a daily carnitine dose of 100 mg/kg body weight which better reflects the dose used in clinical trials. In order to evaluate possible detrimental effects of carnitine supplementation, we investigated parameters of lipid metabolism and stress signaling pathways in the liver and performed a genome-wide transcriptome analysis of skeletal muscle in the mice at advanced age.
2018-09-19 | GSE120120 | GEO
Project description:Eubacterium limosum ATCC 8486 makes acetate and butyrate from various substrates and is found in the human intestine. The proteome of L-carnitine-grown Eubacterium limosum was obtained in order to identify enzymes required for growth on L-carnitine, in particular to identify components that are unique to growth on L-carnitine in comparison to other substrates for acetogenesis, such as lactic acid. L-carnitine and derviatives are converted to trimethylamine (TMA) by certain members of the gut microbiome, metabolism of TMA is now tied to progression of cardiovascular disease. Demethylation of carnitine is observed during growth of Eubacterium limosum on this substrate, and does not produce TMA. Carnitine demethylation by organisms like Eubacterium limosum could lessen TMA production in the gut, thereby lessening the propensity towards atherorsclerosis caused by metabolism of TMA in the body. The carnitine proteome led to the description of a carnitine:tetrahydrofolate methyltransferase system. The key carnitine demethylating enzyme is a member of the widespread TMA methyltransferase protein superfamily.
2020-06-19 | PXD013961 | Pride
Project description:Eubacterium limosum ATCC 8486 makes acetate and butyrate from various substrates and is found in the human intestine. The proteome of gamma-butyrobetaine -grown Eubacterium limosum was obtained in order to identify enzymes required for growth on gamma-butyrobetaine, in particular to identify components that are unique to growth on gamma-butyrobetaine in comparison to other substrates for acetogenesis, such as lactic acid, L-carnitine, or proline betaine. Gamma-butyrobetaine is converted to trimethylamine (TMA) by certain members of the gut microbiome. Subsequent liver metabolism of TMA is now tied to progression of cardiovascular disease. Demethylation of gamma-butyrobetaine is observed during growth of Eubacterium limosum on this substrate, and does not produce TMA. Gamma-butyrobetaine demethylation by organisms like Eubacterium limosum could lessen TMA production in the gut, thereby lessening the propensity towards atherosclerosis caused by metabolism of TMA in the body. This proteome led to discovery of gamma-butyrobetaine:tetrahydrofolate methyltransferase system. The key gamma-butyrobetaine demethylating enzyme is a member of the widespread TMA methyltransferase protein superfamily.
2021-11-04 | PXD020152 | Pride
Project description:Microarray analysis of the effect of L-carnitine supplementation on global expression of Sachharomyces cerevisiae cultures in logarithmic growing conditions and after exposure to H2O2 induced oxidative stress; L-Carnitine plays a well documented role in eukaryotic energy homeostasis by acting as a shuttling molecule for activated acyl residues across intracellular membranes. This activity is supported by carnitine acyl-transferases and transporters, and is referred to as the carnitine shuttle. However, several pleiotropic and often beneficial effects of carnitine in humans have been reported that appear to be unrelated to the shuttling activity, but little conclusive evidence regarding the molecular networks that would be affected by carnitine exist. We have recently demonstrated a protective role of carnitine in oxidative stress in yeast that is independent of the carnitine shuttle. A DNA microarray-based global gene expression analysis identified Cyc3p, a cytochrome c heme lyase, as being important for carnitine's protective impact in oxidative stress conditions. These findings establish a direct genetic link to a carnitine-related phenotype that is independent of the shuttle system. The data suggest that the yeast Saccharomyces cerevisiae should provide a useful model for further elucidation of carnitine's physiological roles. Experiment Overall Design: Yeast cultures was grown to mid-log phase with and without carnitine supplementation to a final concentration of 100 mg/L. A second set was grown to mid log phase, with and without carnitine supplementation and exposed to 0.4 mM H2O2 for 30 min. The experiments were performed using biological duplicate.
2009-07-04 | E-GEOD-16346 | biostudies-arrayexpress
Project description:Microarray analysis of the effect of L-carnitine supplementation on global expression of Sachharomyces cerevisiae cultures in logarithmic growing conditions and after exposure to H2O2 induced oxidative stress L-Carnitine plays a well documented role in eukaryotic energy homeostasis by acting as a shuttling molecule for activated acyl residues across intracellular membranes. This activity is supported by carnitine acyl-transferases and transporters, and is referred to as the carnitine shuttle. However, several pleiotropic and often beneficial effects of carnitine in humans have been reported that appear to be unrelated to the shuttling activity, but little conclusive evidence regarding the molecular networks that would be affected by carnitine exist. We have recently demonstrated a protective role of carnitine in oxidative stress in yeast that is independent of the carnitine shuttle. A DNA microarray-based global gene expression analysis identified Cyc3p, a cytochrome c heme lyase, as being important for carnitine's protective impact in oxidative stress conditions. These findings establish a direct genetic link to a carnitine-related phenotype that is independent of the shuttle system. The data suggest that the yeast Saccharomyces cerevisiae should provide a useful model for further elucidation of carnitine's physiological roles.
2009-06-29 | GSE16346 | GEO
Project description:rs07-01_carnitine - carnitine effect - Effect of carnitine on the transcriptome of A. thaliana - Our objective is the description of the existence of an intracellular transport depend on the carnitine at Arabidopsis thaliana. For that, we planned the study of the response of the transcriptome in the presence of exogenic L-carnitine. Seedlings WT are cultivated on medium MS, 6 independent times. At 144h, the seedlings are collected and pools are formed with 3 samples. We proceed in the same way for the seedlings which are cultivated on medium MS containing L-carnitine 5mM. Keywords: treated vs untreated comparison
2008-03-05 | GSE10676 | GEO
Project description:Carnitine is a water soluble quaternary amine which is essential for normal function of all tissues. Besides improving performance characteristics of livestock animals carnitine has attracted scientific interest due to several health-related effects, like protection against neurodegeneration, mitochondrial decay, and oxidative stress, improvement of glucose tolerance and insulin sensitivity as well as reduction of hepatic steatosis. To gain insight into mechanisms through which carnitine exerts its beneficial metabolic effects, we fed piglets either a control or a carnitine supplemented diet, and analyzed the transcriptome in the liver, which plays a central role in whole body metabolism. Total RNA was isolated from pig liver samples for hybridization on Affymetrix GeneChip porcine genome arrays. Two RNA pools, each for the control group and the carnitine group, were used. Each RNA pool comprised RNA from 4 pigs.
2010-07-15 | E-GEOD-22931 | biostudies-arrayexpress
Project description: Not available
| S-EPMC3964110 | biostudies-literature