L-methionine, also known as L-aminomethane, is one of the eight essential amino acids required by the human body and has important applications in the fields of feed, medicine, and food. In this study, an L-methionine high-yielding strain was constructed using a modular metabolic engineering strategy based on the M2 strain (Escherichia coli W3110 ΔIJAHFEBC/PAM) previously constructed in our laboratory. Firstly, the production of one-carbon module methyl donors was enhanced by overexpression of methylenetetrahydrofolate reductase (methylenetetrahydrofolate reductase, MetF) and screening of hydroxymethyltransferase (GlyA) from different sources, optimizing the one-carbon module. Subsequently, cysteamine lyase (hydroxymethyltransferase, MalY) and cysteine internal transporter gene (fliY) were overexpressed to improve the supply of L-homocysteine and L-cysteine, two precursors of the one-carbon module. The production of L-methionine in shake flask fermentation was increased from 2.8 g/L to 4.05 g/L, and up to 18.26 g/L in a 5 L fermenter. The results indicate that the one carbon module has a significant impact on the biosynthesis of L-methionine, and efficient biosynthesis of L-methionine can be achieved through optimizing the one carbon module. This study may facilitate further improvement of microbial fermentation production of L-methionine.
Humans ; Methionine ; Methylenetetrahydrofolate Reductase (NADPH2) ; Carbon ; Cysteine ; Escherichia coli/genetics* ; Hydroxymethyl and Formyl Transferases ; Carrier Proteins ; Escherichia coli Proteins

Methylation plays a vital role in biological systems. SAM (S-adenosyl-L-methionine), an abundant cofactor in life, acts as a methyl donor in most biological methylation reactions. SAM-dependent methyltransferases (MTase) transfer a methyl group from SAM to substrates, thereby altering their physicochemical properties or biological activities. In recent years, many SAM analogues with alternative methyl substituents have been synthesized and applied to methyltransferases that specifically transfer different groups to the substrates. These include functional groups for labeling experiments and novel alkyl modifications. This review summarizes the recent progress in the synthesis and application of SAM methyl analogues and prospects for future research directions in this field.
S-Adenosylmethionine/metabolism* ; Methionine ; Methyltransferases/metabolism* ; Methylation ; Racemethionine

OBJECTIVE: To investigate the effects of methionine restriction on proliferation, cell cycle and apoptosis of human acute leukemia cells. METHODS: Cell Counting Kit-8 (CCK-8) assay was used to detect the effect of methionine restriction on HL-60 and Jurkat cells proliferation. The effect of methionine restriction on cell cycle of HL-60 and Jurkat cells was examined by PI staining. Annexin V-FITC / PI double staining was applied to detect apoptosis of HL-60 and Jurkat cells following methionine restriction. The expression of cell cycle-related proteins cyclin B1, CDC2 and apoptosis-related protein Bcl-2 was evaluated by Western blot assay. RESULTS: Methionine restriction significantly inhibited the proliferation of HL-60 and Jurkat cells in a time-dependent manner (HL-60: r =0.7773, Jurkat: r =0.8725), arrested the cells at G2/M phase (P < 0.001), and significantly induced apoptosis of HL-60 and Jurkat cells (HL-60: P < 0.001; Jurkat: P < 0.05). Furthermore, Western blot analysis demonstrated that methionine restriction significantly reduced the proteins expression of Cyclin B1 (P < 0.05), CDC2 (P < 0.01) and Bcl-2 (P < 0.001) in HL-60 and Jurkat cells. CONCLUSION Acute leukemia cells HL-60 and Jurkat exhibit methionine dependence. Methionine restriction can significantly inhibit the proliferation, promote cell cycle arrest and induce apoptosis of HL-60 and Jurkat cells, which suggests that methionine restriction may be a potential therapeutic strategy for acute leukemia.
Humans ; Cyclin B1/pharmacology* ; Cell Proliferation ; Methionine/pharmacology* ; Cell Cycle ; Apoptosis ; Leukemia, Myeloid, Acute ; Cell Division ; Cell Cycle Proteins ; Jurkat Cells ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; HL-60 Cells

In this study, an ultra-performance liquid chromatography-quadrupole time-of-flight high resolution mass spectrometer(UPLC-Q-TOF-HRMS) was used to investigate the effects of the active ingredients in Periploca forrestii compound on spleen metabolism in rats with collagen-induced arthritis(CIA), and its potential anti-inflammatory mechanism was analyzed by network pharmacology. After the model of CIA was successfully established, the spleen tissues of rats were taken 28 days after administration. UPLC-Q-TOF-HRMS chromatograms were collected and analyzed by principal component analysis(PCA), orthogonal partial least squares discriminant analysis(OPLS-DA), and MetPA. The results showed that as compared with the blank control group, 22 biomarkers in the spleen tissues such as inosine, citicoline, hypoxanthine, and taurine in the model group increased, while 9 biomarkers such as CDP-ethanolamine and phosphorylcholine decreased. As compared with the model group, 21 biomarkers such as inosine, citicoline, CDP-ethanolamine, and phosphorylcholine were reregulated by the active ingredients in P. forrestii. Seventeen metabolic pathways were significantly enriched, including purine metabolism, taurine and hypotaurine metabolism, glycerophospholipid metabolism, and cysteine and methionine metabolism. Network pharmacology analysis found that purine metabolism, glycerophospholipid metabolism, and cysteine and methionine metabolism played important roles in the pathological process of rheumatoid arthritis. This study suggests that active ingredients in P. forrestii compound can delay the occurrence and development of inflammatory reaction by improving the spleen metabolic disorder of rats with CIA. The P. forrestii compound has multi-target and multi-pathway anti-inflammatory mechanism. This study is expected to provide a new explanation for the mechanism of active ingredients in P. forrestii compound against rheumatoid arthritis.
Rats ; Animals ; Periploca ; Cysteine ; Cytidine Diphosphate Choline ; Network Pharmacology ; Phosphorylcholine ; Metabolomics ; Arthritis, Rheumatoid/drug therapy* ; Biomarkers ; Glycerophospholipids ; Methionine ; Purines ; Chromatography, High Pressure Liquid

S-adenosyl-l-methionine (SAM) is ubiquitous in living organisms and plays important roles in transmethylation, transsulfuration and transamination in organisms. Due to its important physiological functions, production of SAM has attracted increasing attentions. Currently, researches on SAM production mainly focus on microbial fermentation, which is more cost-effective than that of the chemical synthesis and the enzyme catalysis, thus easier to achieve commercial production. With the rapid growth in SAM demand, interests in improving SAM production by developing SAM hyper-producing microorganisms aroused. The main strategies for improving SAM productivity of microorganisms include conventional breeding and metabolic engineering. This review summarizes the recent research progress in improving microbial SAM productivity to facilitate further improving SAM productivity. The bottlenecks in SAM biosynthesis and the solutions were also addressed.
S-Adenosylmethionine/metabolism* ; Plant Breeding ; Fermentation ; Metabolic Engineering

OBJECTIVE: To explore the clinical features and genetic basis of a child with Galactosemia. METHODS: A child who had presented at the Children's Hospital Affiliated to Zhengzhou University on November 20, 2019 was selected as the study subject. Clinical data of the child was collected. Whole exome sequencing was carried out for the child. Candidate variants were validated by Sanger sequencing. RESULTS: Clinical manifestations of the child have included anemia, feeding difficulty, jaundice, hypomyotonia, abnormal liver function and coagulation abnormality. Tandem mass spectrometry showed increased citrulline, methionine, ornithine and tyrosine. Urine organic acid analysis showed increased phenyllactic acid, 4-hydroxyphenylacetic acid, 4-hydroxyphenyllactic acid, 4-hydroxyphenylpyruvate and N-acetyltyrosine. Genetic testing revealed that the child has harbored compound heterozygous variants of the GALT gene, namely c.627T>A (p.Y209*) and c.370G>C (p.G124R), which were respectively inherited from her healthy parents. Among these, c.627T>A (p.Y209*) was known as a likely pathogenic variant, while c.370G>C (p. G124R) was unreported previously and also predicted as a likely pathogenic variant(PM1+PM2_Supporting+PP3_Moderate+PPR). CONCLUSION Above discovery has expanded the spectrum of the GALT gene variants underlying Galactosemia. Patients with thrombocytopenia, feeding difficulties, jaundice, abnormal liver function and coagulation abnormality without obvious causes should be analyzed by screening of metabolic diseases in combination with genetic testing.
Child ; Female ; Humans ; Galactosemias/genetics* ; Genetic Testing ; Health Status ; Methionine ; Muscle Hypotonia ; Mutation

Circadian Clocks/genetics* ; Reactive Oxygen Species ; Methionine ; Gastrointestinal Microbiome ; Gastrointestinal Tract ; Racemethionine ; Gene Expression

Objective: To characterize the relationship between the levels of plasma methyl donor and related metabolites (including choline, betaine, methionine, dimethylglycine and homocysteine) and fetal growth in twin pregnancies. Methods: A hospital-based cohort study was used to collect clinical data of 92 pregnant women with twin pregnancies and their fetuses who were admitted to Peking University Third Hospital from March 2017 to January 2018. Fasting blood was collected from the pregnant women with twin pregnancies (median gestational age: 18.9 weeks). The levels of methyl donors and related metabolites in plasma were quantitatively analyzed by high-performance liquid chromatography combined with mass spectrometry. The generalized estimation equation was used to analyze the relationship between maternal plasma methyl donors and related metabolites levels and neonatal outcomes of twins, and the generalized additive mixed model was used to analyze the relationship between maternal plasma methyl donors and related metabolites levels and fetal growth ultrasound indicators. Results: (1) General clinical data: of the 92 women with twin pregnancies, 66 cases (72%) were dichorionic diamniotic (DCDA) twin pregnancies, and 26 cases (28%) were monochorionic diamniotic (MCDA) twin pregnancies. The comparison of the levels of five plasma methyl donors and related metabolites in twin pregnancies with different basic characteristics showed that the median levels of plasma choline and betaine in pregnant women ≥35 years old were higher than those in pregnant women <35 years old, and the differences were statistically significant (all P<0.05). (2) Correlation between plasma methyl donor and related metabolites levels and neonatal growth indicators: after adjusting for confounding factors, plasma homocysteine level in pregnant women with twins was significantly negatively correlated with neonatal birth weight (β=-47.9, 95%CI:-94.3- -1.6; P=0.043). Elevated methionine level was significantly associated with decreased risks of small for gestational age infants (SGA; OR=0.5, 95%CI: 0.3-0.9; P=0.021) and low birth weight infants (OR=0.6, 95%CI: 0.4-0.9; P=0.020). Increased homocysteine level was associated with increased risks of SGA (OR=1.5, 95%CI: 1.0-2.2; P=0.029) and inconsistent growth in twin fetuses (OR=1.9, 95%CI: 1.0-3.7; P=0.049). (3) Correlation between the levels of plasma methyl donors and related metabolites and intrauterine growth indicators of twins pregnancies: for every 1 standard deviation increase in plasma choline level in pregnant women with twin pregnancies, fetal head circumference, abdominal circumference, femoral length and estimated fetal weight in the second trimester increased by 1.9 mm, 2.6 mm, 0.5 mm and 20.1 g, respectively, and biparietal diameter, abdominal circumference and estimated fetal weight increased by 0.7 mm, 3.0 mm and 38.4 g in the third trimester, respectively, and the differences were statistically significant (all P<0.05). (4) Relationship between plasma methyl donor and related metabolites levels in pregnant women with different chorionicity and neonatal birth weight and length: the negative correlation between plasma homocysteine level and neonatal birth weight was mainly found in DCDA twin pregnancy (β=-65.9, 95%CI:-110.6- -21.1; P=0.004). The levels of choline, betaine and dimethylglycine in plasma of MCDA twin pregnancy were significantly correlated with the birth weight and length of newborns (all P<0.05). Conclusion: Homocysteine level is associated with low birth weight in twins, methionine is associated with decreased risk of SGA, and choline is associated with fetal growth in the second and third trimesters of pregnancy.
Adult ; Female ; Humans ; Infant, Newborn ; Pregnancy/metabolism* ; Betaine/metabolism* ; Birth Weight/physiology* ; Choline/metabolism* ; Cohort Studies ; Fetal Development/physiology* ; Fetal Weight/physiology* ; Homocysteine/metabolism* ; Methionine/metabolism* ; Pregnancy, Twin/physiology* ; Biomarkers/metabolism* ; Pregnancy Trimesters/physiology* ; Pregnancy Outcome

Animals ; Cadmium/toxicity* ; Dysbiosis/metabolism* ; Gastrointestinal Microbiome ; Glutamine/pharmacology* ; Methionine ; Mice ; Mice, Inbred C57BL ; Ostreidae ; Protein Hydrolysates ; Tyrosine

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