Flavoprotein monooxygenases(FPMOs) and cytochrome P450(CYP450) oxygenases are pivotal monooxygenases in nature, catalyzing crucial redox reactions in diverse biological processes and contributing to the synthesis of highly complex natural products. While CYP450 enzymes have been extensively reported and studied, numerous FPMOs have also been discovered in past research endeavors, yet their classification, catalytic reactions, and catalytic mechanisms remain to be systematically analyzed. This paper comprehensively reviews the latest advancements in FPMOs research, initiating with a classification based on sequence similarities and distinct structural features. It delves into the catalytic characteristics of three subfamilies(FMO, BVMO, and NMO) within Class B FPMOs of plants, which are integral to biosynthetic pathways of natural products. Class B FPMOs encompass two canonical Rossmann fold motifs(FAD-binding GxGxxG and NADPH-binding GxGxxA), along with a central FMO recognition motif FxGxxxHxxxF/Y/W. These enzymes play a key role in regulating various metabolic routes and precisely modulate plant growth and development. Furthermore, the review summarizes the applications of Class B FPMOs of plants, showcasing through concrete examples their potential in synthesizing natural products such as auxins, indigo, and cyanogenic glycosides. These insights will broaden and deepen our understanding of FPMOs, fostering their transition from fundamental research to practical applications. More optimized biosynthetic pathways can be devised by leveraging FPMOs, conducive to the development of novel strategies and tools for agriculture, plant protection, natural product biosynthesis, and synthetic biology.
Biological Products/metabolism* ; Mixed Function Oxygenases/chemistry* ; Flavoproteins/chemistry* ; Plants/metabolism* ; Plant Proteins/chemistry* ; Cytochrome P-450 Enzyme System/genetics*

OBJECTIVES: Psoriasis is associated with lipid metabolism disorders, but the underlying mechanisms remain unclear. This study aims to investigate the role of trimethylamine N-oxide (TMAO) in lipid metabolism dysregulation in psoriasis. METHODS: An imiquimod (IMQ)-induced psoriasis-like mouse model was used to assess lipid metabolism parameters, TMAO levels, and liver flavin monooxygenase 3 (FMO3) mRNA expression. Blood samples from healthy individuals and psoriatic patients were collected to measure serum TMAO levels and lipid profiles. To clarify the role of TMAO in the lipid metabolism disorder of mice with psoriasis model, exogenous TMAO, choline, or 3,3-dimethyl-1-butanol (DMB) were administered via intraperitoneal injections or diet in IMQ-treated mice. Liver tissues from the mouse models were subjected to RNA sequencing to identify TMAO-regulated signaling pathways. RESULTS: IMQ-induced psoriatic mice exhibited abnormal glucose, insulin, and lipid levels. IMQ treatment also downregulated the hepatic mRNA expression of glucose transporter 2 (Glut2) and silence information regulator 1 (Sirt1), while upregulating glucose transporter 4 (Glut4) and peroxisome proliferator-activated receptor gamma (PPARγ). Elevated serum TMAO levels were observed in both psoriatic patients and IMQ-treated mice. Additionally, liver FMO3 mRNA expression was increased in the psoriatic mouse model. In patients, TMAO levels positively correlated with Psoriasis Area and Severity Index (PASI) scores, serum triglyceride (TG), and total cholesterol (TC) levels. The intraperitoneal injection of TMAO exacerbated lipid dysregulation in IMQ-treated mice. A choline-rich diet further aggravated lipid abnormalities and liver injury in psoriatic mice, whereas DMB treatment alleviated these effects. RNA-Seq analysis demonstrated that TMAO upregulated hepatic microRNA-122 (miR-122), which may suppress the expression of gremlin 2 (GREM2), thus contributing to lipid metabolism disorder. CONCLUSIONS TMAO may promote lipid metabolism dysregulation in psoriasis by modulating the hepatic miR-122/GREM2 pathway.
Animals ; Methylamines/blood* ; Mice ; Psoriasis/chemically induced* ; Lipid Metabolism/drug effects* ; Humans ; Male ; Liver/metabolism* ; Female ; Oxygenases/genetics* ; Disease Models, Animal ; Lipid Metabolism Disorders/etiology* ; Adult ; Mice, Inbred C57BL

S-methyl-L-cysteine sulfoxide (SMCO) is a non-protein sulfur-containing amino acid with a variety of functions. There are few reports on the enzymes catalyzing the biosynthesis of SMCO from S-methyl-L-cysteine (SMC). In this study, the flavin-containing monooxygenase gene derived from Schizosaccharomyces pombe (spfmo) was heterologously expressed in Escherichia coli BL21(DE3) and the enzymatic properties of the expressed protein were analyzed. The optimum catalytic conditions of the recombinant SpFMO were 30 ℃ and pH 8.0, under which the enzyme activity reached 72.77 U/g. An appropriate amount of Mg²⁺ improved the enzyme activity. The enzyme kinetic analysis showed that the K_m and k_cat/K_m of SpFMO on the substrate SMC were 23.89 μmol/L and 61.71 L/(min·mmol), respectively. Under the optimal reaction conditions, the yield of SMCO synthesized from SMC catalyzed by SpFMO was 12.31% within 9 h. This study provides reference for the enzymatic synthesis of SMCO.
Schizosaccharomyces/genetics* ; Escherichia coli/metabolism* ; Recombinant Proteins/metabolism* ; Cysteine/biosynthesis* ; Mixed Function Oxygenases/metabolism* ; Schizosaccharomyces pombe Proteins/metabolism* ; Oxygenases/metabolism* ; Kinetics

Conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) by ten-eleven translocation (TET) family proteins leads to the accumulation of 5hmC in the central nervous system; however, the role of 5hmC in the postnatal brain and how its levels and target genes are regulated by TETs remain elusive. We have generated mice that lack all three Tet genes specifically in postnatal excitatory neurons. These mice exhibit significantly reduced 5hmC levels, altered dendritic spine morphology within brain regions crucial for cognition, and substantially impaired spatial and associative memories. Transcriptome profiling combined with epigenetic mapping reveals that a subset of genes, which display changes in both 5hmC/5mC levels and expression patterns, are involved in synapse-related functions. Our findings provide insight into the role of postnatally accumulated 5hmC in the mouse brain and underscore the impact of 5hmC modification on the expression of genes essential for synapse development and function.
Animals ; Brain/growth & development* ; 5-Methylcytosine/metabolism* ; Mice ; Synapses/genetics* ; Proto-Oncogene Proteins/metabolism* ; DNA-Binding Proteins/metabolism* ; Dioxygenases/metabolism* ; Cognition/physiology* ; Gene Expression ; Mixed Function Oxygenases/metabolism* ; Epigenesis, Genetic ; Mice, Knockout ; Mice, Inbred C57BL

Ten-eleven translocation 1 (TET1) protein is an alpha-ketoglutaric acid (α-KG) and Fe²⁺-dependent dioxygenase. It plays a role in the active demethylation of DNA by hydroxylation of 5-methyl-cytosine (5-mC) to 5-hydroxymethyl-cytosine (5-hmC). Ten-eleven translocation 1 (TET1) protein is involved in maintaining genome methylation homeostasis and epigenetic regulation. Abnormally expressed TET1 and 5-mC oxidative derivatives have become potential markers in various biological and pathological processes and a research focus in the fields of embryonic development and malignant tumors. This paper introduces the structure and demethylation mechanism of TET1, reviews the research status of epigenetic regulation by TET1 in embryonic development, immune responses, stem cell regulation, cancer progression, and nervous system development, and briefs the upstream regulatory mechanism of TET1, hoping to provide new inspirations for further research in related fields.
Proto-Oncogene Proteins/genetics* ; Epigenesis, Genetic ; Humans ; DNA-Binding Proteins/metabolism* ; DNA Methylation ; Mixed Function Oxygenases/metabolism* ; 5-Methylcytosine/analogs & derivatives* ; Animals ; Embryonic Development/genetics* ; Neoplasms/genetics* ; Dioxygenases/metabolism*

The association among plasma trimethylamine-N-oxide (TMAO), FMO3 polymorphisms, and chronic heart failure (CHF) remains to be elucidated. TMAO is a microbiota-dependent metabolite from dietary choline and carnitine. A prospective study was performed including 955 consecutively diagnosed CHF patients with reduced ejection fraction, with the longest follow-up of 7 years. The concentrations of plasma TMAO and its precursors, namely, choline and carnitine, were determined by liquid chromatography-mass spectrometry, and the FMO3 E158K polymorphisms (rs2266782) were genotyped. The top tertile of plasma TMAO was associated with a significant increment in hazard ratio (HR) for the composite outcome of cardiovascular death or heart transplantation (HR = 1.47, 95% CI = 1.13-1.91, P = 0.004) compared with the lowest tertile. After adjustments of the potential confounders, higher TMAO could still be used to predict the risk of the primary endpoint (adjusted HR = 1.33, 95% CI = 1.01-1.74, P = 0.039). This result was also obtained after further adjustment for carnitine (adjusted HR = 1.33, 95% CI = 1.01-1.74, P = 0.039). The FMO3 rs2266782 polymorphism was associated with the plasma TMAO concentrations in our cohort, and lower TMAO levels were found in the AA-genotype. Thus, higher plasma TMAO levels indicated increased risk of the composite outcome of cardiovascular death or heart transplantation independent of potential confounders, and the FMO3 AA-genotype in rs2266782 was related to lower plasma TMAO levels.
Carnitine ; Choline/metabolism* ; Chronic Disease ; Heart Failure/genetics* ; Humans ; Methylamines ; Oxygenases ; Prospective Studies

To explore the mechanism of tea albino variation and high theanine formation, 'Fuyun 6' and a new theanine-rich tea cultivar 'Fuhuang 2' were as materials in this study, pigment content, metabolome and transcriptome of the two cultivars were analyzed by ultramicroelectron microscopy, widely targeted metabolomics, targeted metabolomics and transcriptomics. The results showed that five catechins, theobromine, caffeine, and 20 free amino acids, including theanine, glutamine, arginine, etc., were identified by targeted metabolomics. The amino acid content of 'Fuhuang 2' was significantly higher than that of 'Fuyun 6', and the theanine content was as high as 57.37 mg/g in 'Fuhuang 2'. The ultrastructure of leaves showed that the chloroplast cell structure of 'Fuhuang 2' was fuzzy, most of the grana lamellae were arranged in disorder, with large gaps, and the thylakoids were filiform. The determination of pigments showed that compared with 'Fuyun 6', the contents of chlorophyll A and B, carotenoids, flavonoids and other pigments of 'Fuhuang 2' decreased significantly, some important pigment-related-genes, such as chlorophyllase (CLH), 9-cis-epoxycarotenoid dioxygenase (NCED), flavonoid 3β-hydroxylase (F3H) and flavonoid 3', 5'-hydroxylase (F3'5'H) were significantly changed. Compared with 'Fuyun 6', 'Fuhuang 2' identified 138 significantly changed metabolites (SCMs) and 658 differentially expressed genes (DEGs). KEGG enrichment analysis showed that SCMs and DEGs were significantly enriched in amino acid biosynthesis, glutathione metabolism and TCA cycle. In general, the albino phenotype of 'Fuhuang 2' may be caused by a deficiency in photosynthetic proteins, chlorophyll metabolism genes and chlorophyll content. The accumulation of high theanine in 'Fuhuang 2' may be due to the low nitrogen consumption in yellowed leaves and the lack of carbon skeleton, amino and nitrogen resources are stored more effectively, resulting in the up regulation of metabolites and related gene expression in the amino acid synthesis pathway, theanine has become a significant accumulation of nitrogen-containing compounds in yellowed leaves.
Camellia sinensis/genetics* ; Chlorophyll A/metabolism* ; Plant Proteins/genetics* ; Plant Leaves/chemistry* ; Chlorophyll/metabolism* ; Transcriptome ; Flavonoids/metabolism* ; Amino Acids/genetics* ; Tea ; Mixed Function Oxygenases/metabolism* ; Nitrogen/metabolism*

The methylation of cytosine is one of the most fundamental epigenetic modifications in mammalian genomes, and is involved in multiple crucial processes including gene expression, cell differentiation, embryo development and oncogenesis. In the past, DNA methylation was thought to be an irreversible process, which could only be diluted passively through DNA replication. It is now becoming increa-singly obvious that DNA demethylation can be an active process and plays a crucial role in biological processes. Ten eleven translocation (TET) proteins are the key factors modulating DNA demethylation. This family contains three members: TET1, TET2 and TET3. Although three TET proteins have relatively conserved catalytic domains, their roles in organisms are not repeated, and their expression has significant cell/organ specificity. TET1 is mainly expressed in embryonic stem cells, TET2 is mainly expressed in hematopoietic system, and TET3 is widely expressed in cerebellum, cortex and hippocampus. This family catalyzes 5-methylcytosine to 5-hydroxymethylcytosine and other oxidative products, reactivates silenced-gene expression, in turn maintains stem cell pluripotency and regulates lineage specification. With the development of tissue engineering, organ transplantation, autologous tissue transplantation and artificial prosthesis have been widely used in clinical treatment, but these technologies have limitations. Regenerative medicine, which uses stem cells and stem cell related factors for treatment, may provide alternative therapeutic strategies for multiple diseases. Among all kinds of human stem cells, adipose-derived stem cells (ADSCs) are the most prospective stem cell lineage since they have no ethical issues and can be easily obtained with large quantities. To date, ADSCs have been shown to have strong proli-feration capacity, secrete numerous soluble factors and have multipotent differentiation ability. However, the underlying mechanism of the proliferation, secretion, acquired pluripotency, and lineage specific differentiation of ADSCs are still largely unknown. Some studies have explored the role of epigenetic regulation and TET protein in embryonic stem cells, but little is known about its role in ADSCs. By studying the roles of TET proteins and 5-hydroxymethylcytosine in ADSCs, we could provide new theoretical foundation for the clinical application of ADSCs and the stem cell-based therapy. In the future, combined with bioprinting technology, ADSCs may be used in tissue and organ regeneration, plastic surgery reconstruction and other broader fields.
5-Methylcytosine/analogs & derivatives* ; Animals ; DNA Methylation ; DNA-Binding Proteins/genetics* ; Epigenesis, Genetic ; Humans ; Mixed Function Oxygenases/metabolism* ; Prospective Studies ; Proto-Oncogene Proteins/metabolism* ; Regenerative Medicine ; Stem Cells/metabolism*

Hyoscyamine and scopolamine are two main alkaloids in Atropa belladonna with great medicinal value. In this paper, the contents of hyoscyamine and scopolamine, the upstream products in alkaloid synthesis, and the expression levels of key enzyme genes PMT, TRⅠ and H6H in secondary metabolism of A. belladonna seedlings were measured to clarify the mechanism of nitrogen forms regulating alkaloids synthesis.The results showed that the 50/50 (NH⁺₄/NO⁻₃) treatment was more favorable for the accumulation of alkaloids and the conversion of hyoscyamine to scopolamine. The content of putrescine was almost consistent with the change of key enzymes activities in the synthesis of putrescine, they both increased with the rise of ammonium ratio, reaching the highest at 75/25 (NH⁺₄/NO⁻₃). The detection of signaling molecule nitric oxide (NO) showed that the NO concentration decreased with the decrease of nitrate proportion. Further detection of gene expression levels of PMT, TRⅠ and H6H in TAs synthesis pathway showed that a certain amount of ammonium promoted the expression of PMT and H6H in roots. When the ratio of ammonium to nitrate was 50/50, PMT, TRⅠ and H6H in leaves and roots had higher expression levels. It can be speculated that the regulation of the formation of hyoscyamine to scopolamine by nitrogen forms mainly through affecting the expression of key enzyme genes. 50/50 (NH⁺₄/NO⁻₃) treatment increased the gene expression of TRⅠ in both leaves and roots as well as PMT and H6H in roots, promoting the synthesis of putrescine to hyoscyamine and the conversion of hyoscyamine to scopolamine.
Atropa belladonna ; enzymology ; genetics ; Gene Expression Regulation, Plant ; Hyoscyamine ; biosynthesis ; Mixed Function Oxygenases ; Nitrogen ; metabolism ; Scopolamine ; metabolism

OBJECTIVEAberrant expression of ten-eleven translocation 1 (TET1) plays a critical role in tumor development and progression. We systematically summarized the latest research progress on the role and mechanisms of TET1 in cancer biology.

DATA SOURCESRelevant articles published in English from 1980 to April 2016 were selected from the PubMed database. The terms "ten-eleven translocation 1," "5mC," "5hmC," "microRNA," "hypoxia," and "embryonic stem cell" were used for the search.

STUDY SELECTIONArticles focusing on the role and mechanism of TET1 in tumor were reviewed, including clinical and basic research articles.

RESULTSTET proteins, the key enzymes converting 5-methylcytosine to 5-hydroxymethylcytosine, play vital roles in DNA demethylation regulation. Recent studies have shown that loss of TET1 is associated with tumorigenesis and can be used as a potential biomarker for cancer therapy, which indicates that TET1 serves as tumor suppressor gene. Moreover, besides its dioxygenase activity, TET1 could induce epithelial-mesenchymal transition and act as a coactivator to regulate gene transcription, such as developmental regulator in embryonic stem cells (ESCs) and hypoxia-responsive gene in cancer. The regulation of TET1 is also correlated with microRNA in a posttranscriptional modification process. Hence, it is complex but critical to comprehend the mechanisms of TET1 in the biology of ESCs and cancer.

CONCLUSIONSTET1 not only serves as a demethylation enzyme but also plays multiple roles during tumorigenesis and progression. More studies should be carried out to elucidate the exact mechanisms of TET1 and its associations with cancer before considering it as a therapeutic tool.

Animals ; Biomarkers ; metabolism ; Carcinogenesis ; genetics ; metabolism ; pathology ; Humans ; MicroRNAs ; genetics ; Mixed Function Oxygenases ; genetics ; metabolism ; Proto-Oncogene Proteins ; genetics ; metabolism