Branched chain amino acids, as essential amino acids, can be used to synthesize nitrogen-containing compounds and also act as signal molecules to regulate substance metabolism. Studies have shown that the elevated level of branched chain amino acids is closely related to insulin resistance and type 2 diabetes. It can affect insulin signal transduction by activating mammalian target of rapamycin (mTOR) signal pathway, and regulate insulin resistance by damaging lipid metabolism and affecting mitochondrial function. In addition, abnormal catabolism of branched amino acids can lead to the accumulation of metabolic intermediates, such as branched chain α-keto acids, 3-hydroxyisobutyrate and β-aminoisobutyric acid. Branched chain α-keto acids and 3-hydroxyisobutyrate can induce insulin resistance by affecting insulin signaling pathway and damaging lipid metabolism. β-aminoisobutyric acid can improve insulin resistance by reducing lipid accumulation and inflammatory reaction and enhancing fatty acid oxidation. This paper systematically reviewed the regulatory effects and mechanisms of branched chain amino acids and their metabolic intermediates on insulin resistance, which will provide a new direction for the prevention and treatment of insulin resistance and type 2 diabetes.
Humans ; Amino Acids, Branched-Chain/metabolism* ; Insulin Resistance/physiology* ; Diabetes Mellitus, Type 2 ; Insulin/pharmacology* ; Keto Acids/metabolism*

ω-transaminase (ω-TA) is a natural biocatalyst that has good application potential in the synthesis of chiral amines. However, the poor stability and low activity of ω-TA in the process of catalyzing unnatural substrates greatly hampers its application. To overcome these shortcomings, the thermostability of (R)-ω-TA (AtTA) from Aspergillus terreus was engineered by combining molecular dynamics simulation assisted computer-aided design with random and combinatorial mutation. An optimal mutant AtTA-E104D/A246V/R266Q (M3) with synchronously enhanced thermostability and activity was obtained. Compared with the wild- type (WT) enzyme, the half-life t_1/2 (35 ℃) of M3 was prolonged by 4.8-time (from 17.8 min to 102.7 min), and the half deactivation temperature (T¹⁰₅₀) was increased from 38.1 ℃ to 40.3 ℃. The catalytic efficiencies toward pyruvate and 1-(R)-phenylethylamine of M3 were 1.59- and 1.56-fold that of WT. Molecular dynamics simulation and molecular docking showed that the reinforced stability of α-helix caused by the increase of hydrogen bond and hydrophobic interaction in molecules was the main reason for the improvement of enzyme thermostability. The enhanced hydrogen bond of substrate with surrounding amino acid residues and the enlarged substrate binding pocket contributed to the increased catalytic efficiency of M3. Substrate spectrum analysis revealed that the catalytic performance of M3 on 11 aromatic ketones were higher than that of WT, which further showed the application potential of M3 in the synthesis of chiral amines.
Transaminases/chemistry* ; Molecular Docking Simulation ; Amines/chemistry* ; Pyruvic Acid/metabolism* ; Enzyme Stability

Heme, which exists widely in living organisms, is a porphyrin compound with a variety of physiological functions. Bacillus amyloliquefaciens is an important industrial strain with the characteristics of easy cultivation and strong ability for expression and secretion of proteins. In order to screen the optimal starting strain for heme synthesis, the laboratory preserved strains were screened with and without addition of 5-aminolevulinic acid (ALA). There was no significant difference in the heme production of strains BA, BAΔ6 and BAΔ6ΔsigF. However, upon addition of ALA, the heme titer and specific heme production of strain BAΔ6ΔsigF were the highest, reaching 200.77 μmol/L and 615.70 μmol/(L·g DCW), respectively. Subsequently, the hemX gene (encoding the cytochrome assembly protein HemX) of strain BAΔ6ΔsigF was knocked out to explore its role in heme synthesis. It was found that the fermentation broth of the knockout strain turned red, while the growth was not significantly affected. The highest ALA concentration in flask fermentation reached 82.13 mg/L at 12 h, which was slightly higher than that of the control 75.11 mg/L. When ALA was not added, the heme titer and specific heme production were 1.99 times and 1.45 times that of the control, respectively. After adding ALA, the heme titer and specific heme production were 2.08 times and 1.72 times higher than that of the control, respectively. Real-time quantitative fluorescent PCR showed that the expressions of hemA, hemL, hemB, hemC, hemD, and hemQ genes at transcription level were up-regulated. We demonstrated that deletion of hemX gene can improve the production of heme, which may facilitate future development of heme-producing strain.
Gene Deletion ; Bacillus amyloliquefaciens/metabolism* ; Aminolevulinic Acid/metabolism* ; Heme/metabolism* ; Fermentation

OBJECTIVE: To explore the clinical characteristics and variants of ATP7A gene in a child with Menkes disease. METHODS: A child with Menkes disease diagnosed at the West China Second Hospital of Sichuan University and its family members in March 2022 was selected as the study subjects. Clinical manifestations and results of laboratory tests and genetic testing were summarized. RESULTS: The main manifestations of the child included seizures, global development delay, facial dysmorphism, sparse and curly hair, increased lactate and pyruvate, and significantly decreased cuprin. EEG showed frequent issuance of multifocal spikes, spines, polyspines (slow) and polymorphic slow waves. Multiple tortuous vascular shadows were observed on cranial MRI. Whole exome sequencing revealed that the child has harbored a hemizygous c.3076delA (p.ile1026*) variant of the ATP7A gene, which was inherited from his mother. The variant may lead to premature termination of protein translation. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was predicted as pathogenic (PVS1+PM2+PP4). CONCLUSION The c.3076delA (p.Ile1026*) variant of the ATP7A gene probably underlay the Menkes disease in this child. Above finding has provided evidence for clinical diagnosis. The significantly increased lactic acid and pyruvate can be used as a reference for the diagnosis and management of Menkes disease. Microscopic abnormalities in the hair of the carriers may also facilitate their diagnosis.
Child ; Humans ; Copper-Transporting ATPases/genetics* ; East Asian People ; Menkes Kinky Hair Syndrome/genetics* ; Mutation ; Pedigree ; Peptide Fragments ; Pyruvic Acid

L-glutamic acid is the world's largest bulk amino acid product that is widely used in the food, pharmaceutical and chemical industries. Using Corynebacterium glutamicum G01 as the starting strain, the fermentation by-product alanine content was firstly reduced by knocking out the gene encoding alanine aminotransferase (alaT), a major by-product related to alanine synthesis. Secondly, since the α-ketoglutarate node carbon flow plays an important role in glutamate synthesis, the ribosome-binding site (RBS) sequence optimization was used to reduce the activity of α-ketoglutarate dehydrogenase and enhance the glutamate anabolic flow. The endogenous conversion of α-ketoglutarate to glutamate was also enhanced by screening different glutamate dehydrogenase. Subsequently, the glutamate transporter was rationally desgined to improve the glutamate efflux capacity. Finally, the fermentation conditions of the strain constructed using the above strategy were optimized in 5 L fermenters by a gradient temperature increase combined with a batch replenishment strategy. The glutamic acid production reached (135.33±4.68) g/L, which was 41.2% higher than that of the original strain (96.53±2.32) g/L. The yield was 55.8%, which was 11.6% higher than that of the original strain (44.2%). The combined strategy improved the titer and the yield of glutamic acid, which provides a reference for the metabolic modification of glutamic acid producing strains.
Glutamic Acid ; Corynebacterium glutamicum/genetics* ; Ketoglutaric Acids ; Metabolic Engineering ; Alanine

Salicylate 2-O-β-d-glucoside (SAG) is a derivative of salicylate in plants. Recent reports showed that SAG could be considered as a potential anti-inflammatory substance due to its anti-inflammatory and analgesic effects, and less irritation compared with salicylic acid and aspirin. The biological method uses renewable resources to produce salicylic acid compounds, which is more environmentally friendly than traditional industry methods. In this study, Escherichia coli Tyr002 was used as the starting strain, and a salicylic acid producing strain of E. coli was constructed by introducing the isochorismate pyruvate lyase gene pchB from Pseudomonas aeruginosa. By regulating the expression of the key genes in the downstream aromatic amino acid metabolic pathways, the titer of salicylic acid reached 1.05 g/L in shake flask fermentation. Subsequently, an exogenous salicylic acid glycosyltransferase was introduced into the salicylic acid producing strain to glycosylate the salicylic acid. The newly engineered strain produced 5.7 g/L SAG in shake flask fermentation. In the subsequent batch fed fermentation in a 5 L fermentation tank, the titer of SAG reached 36.5 g/L, which is the highest titer reported to date. This work provides a new route for biosynthesis of salicylate and its derivatives.
Escherichia coli/genetics* ; Glucosides ; Metabolic Engineering ; Salicylic Acid ; Pyruvic Acid

Silver nanoparticles (AgNPs) is known as one of the most valuable metal nanoparticles in antibacterial and anticancer application. AgNPs-resistant bacteria has been documented, but it is unclear whether cancer cells can also escape the anti-cancer effect of AgNPs. In this study, we aimed to investigate this phenomenon and its underlying mechanism. The antibacterial activity and cytotoxicity of AgNPs were measured in the presence of HeLa cell metabolites. The status of AgNPs in the system associated with metabolites were characterized by UV-Vis, Zetasizer Nano ZS, and transmission electron microscopy. Non-targeted metabolomics was used to reveal the metabolites components that bind with AgNPs. HeLa cells were injected intraperitoneally to establish the tumor-bearing mice model, and the stability of AgNPs in mice serum was analyzed. The results manifested that HeLa cell metabolites inhibited the anticancer and antibacterial effects of AgNPs in a dose-dependent manner by causing AgNPs aggregation. Effective metabolites that inhibited the biological activity of AgNPs were stable in 100 ℃, insoluble in chloroform, containing sulfur elements, and had a molecular weight less than 1 kDa in molecular weight. There were 115 compounds bound with AgNPs. In vitro experiments showed that AgNPs aggregation occurred only when the concentration of α-ketoglutarate (AKG) and glutathione (GSH) together reached a certain threshold. Interestingly, the concentration of AKG and GSH in HeLa cellular metabolites was 10 and 6 times higher than that in normal cervical epithelial cells, respectively, which explained why the threshold was reached. Furthermore, the stability of AgNPs in the serum of tumor-bearing mice decreased by 20% (P < 0.05) compared with the healthy mice. In conclusion, our study demonstrates that HeLa cells escaped the anti-cancer effect of AgNPs through the synergistic effect of AKG and GSH, suggesting the need to develop strategies to overcome this limitation.
Humans ; Animals ; Mice ; HeLa Cells ; Silver/pharmacology* ; Ketoglutaric Acids/pharmacology* ; Metal Nanoparticles ; Anti-Bacterial Agents/pharmacology* ; Glutathione ; Microbial Sensitivity Tests

Pyroptosis ; Ketoglutaric Acids ; Gasdermins ; Intracellular Signaling Peptides and Proteins/metabolism* ; Caspases/metabolism* ; Inflammasomes/metabolism*

Objective: To analyze the clinical and genetic features of patients with mitochondrial pyruvate carrier deficiency (MPYCD). Methods: This was a case series research. The clinical data, genetic characteristics, and glutamine treatment efficacy of 3 patients diagnosed with MPYCD at the Department of Neurology, Beijing Children's Hospital, Capital Medical University and Department of Pediatrics, Guizhou Provincial People's Hospital, from August 2019 to June 2023 were retrospectively collected. A literature search with "MPC1 gene" "MPC2 gene and" "mitochondrial pyruvate carrier deficiency" as keywords was conducted at the Wanfang Data Knowledge Service Platform, China National Knowledge Infrastructure (CNKI) and PubMed (up to June 2023). Clinical and genetic characteristics of patients with MPYCD were summarized. Results: Case 1 was a 3 years and 11 months old boy, while case 2 was a 4 years and 10 months old boy and case 3 was an 8 years and 9 months old girl. Case 2 and case 3 were siblings from one consanguineous family. All 3 patients presented with general developmental delay, growth failure and elevated serum lactate. Cranial magnetic resonance imaging (MRI) showed subtle bilateral symmetrical T2 signal hyperintensity in basal ganglia and thalamus in case 1, but normal in case 2 and 3. Trio-WES revealed case 1 harboring compound heterozygous missense variants c.208G>A (p.Ala70Thr) and c.290G>A (p.Arg97Gln) in MPC1 gene, while case 2 and 3 revealed a homozygous variant c.290G>A (p.Arg97Gln) in the same gene. All 3 cases were diagnosecl as MPYCD. Clinical symptoms including motor ability, cognition and activity endurance were improved in these 3 patients after taking glutamine for 2 years. A total of 5 articles published in English were reviewed, and no Chinese literature was found. Including these 3 cases, 15 cases were enrolled for analysis. Eleven patients carried MPC1 gene variants and 4 cases carried MPC2 gene variants. Except for 3 cases died during prenatal period, 9 of 12 enrolled born cases were onset before 6 months old. The most common clinical symptoms were mental and motor general developmental delay, microcephaly, growth failure and hypotonia. All patients had elevated blood lactate and pyruvate, but the ratio of lactate/pyruvate was normal. Seven patients performed cranial MRI, 3 exhibited non-specific changes, 2 showed bilateral symmetrical T2 signal hyperintensity in basal ganglia and thalamus, and 3 were normal. A total of 5 MPC1 gene missense variants and 2 MPC2 gene variants were identified in 15 cases. Conclusions: Onset age of patients with MPYCD is usually within 6 months. The main clinical characteristics are developmental delay, microcephaly and growth failure, accompanied by increased serum lactate and pyruvate. Glutamine supplement could lead to clinical improvements.
Child ; Female ; Humans ; Male ; Glutamine ; Lactates ; Microcephaly ; Monocarboxylic Acid Transporters ; Pyruvates ; Retrospective Studies ; Child, Preschool

OBJECTIVES: To study the metabolic mechanism of neonatal sepsis at different stages by analyzing the metabolic pathways involving the serum metabolites with significant differences in neonates with sepsis at different time points after admission. METHODS: A total of 20 neonates with sepsis who were hospitalized in the Department of Neonatology, Hunan Provincial People's Hospital, from January 1, 2019 to January 1, 2020 were enrolled as the sepsis group. Venous blood samples were collected on days 1, 4, and 7 after admission. Ten healthy neonates who underwent physical examination during the same period were enrolled as the control group. Ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry was used for the metabonomic analysis of serum samples to investigate the change in metabolomics in neonates with sepsis at different time points. RESULTS: On day 1 after admission, the differentially expressed serum metabolites between the sepsis and control groups were mainly involved in the biosynthesis of terpenoid skeleton. For the sepsis group, the differentially expressed serum metabolites between days 1 and 4 after admission were mainly involved in pyruvate metabolism, and those between days 4 and 7 after admission were mainly involved in the metabolism of cysteine and methionine. The differentially expressed serum metabolites between days 1 and 7 after admission were mainly involved in ascorbic acid metabolism. CONCLUSIONS The metabolic mechanism of serum metabolites varies at different stages in neonates with sepsis and is mainly associated with terpenoid skeleton biosynthesis, pyruvate metabolism, cysteine/methionine metabolism, and ascorbic acid metabolism.
Ascorbic Acid ; Cysteine ; Humans ; Infant, Newborn ; Metabolomics ; Methionine ; Neonatal Sepsis ; Pyruvates ; Sepsis