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*

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*

17α hydroxylase is a key enzyme for the conversion of progesterone to prepare various progestational drug intermediates. To improve the specific hydroxylation capability of this enzyme in steroid biocatalysis, the CYP260A1 derived from cellulose-mucilaginous bacteria Sorangium cellulosum Soce56 and the Fpr and bovine adrenal-derived Adx_4-108 derived from Escherichia coli str. K-12 were used to construct a new electron transfer system for the conversion of progesterone. Selective mutation of CYP260A1 resulted in a mutant S276I with significantly enhanced 17α hydroxylase activity, and the yield of 17α-OH progesterone reached 58% after optimization of the catalytic system in vitro. In addition, the effect of phosphorylation of the ferredoxin Adx_4-108 on 17α hydroxyl activity was evaluated using a targeted mutation technique, and the results showed that the mutation Adx_4-108T69E transferred electrons to S276I more efficiently, which further enhanced the catalytic specificity in the C17 position of progesterone, and the yield of 17α-OH progesterone was eventually increased to 74%. This study provides a new option for the production of 17α-OH progesterone by specific transformation of bacterial-derived 17α hydroxylase, and lays a theoretical foundation for the industrial production of progesterone analogs using biotransformation method.
Animals ; Cattle ; Progesterone/metabolism* ; Hydroxylation ; Biocatalysis ; Electron Transport ; Mixed Function Oxygenases/metabolism*

The 4-hydroxyphenylacetate 3-hydroxylase (4HPA3H), originated from Escherichia coli, converts p-coumaric acid to caffeic acid. In order to improve the efficiency of caffeic acid biosynthesis, we engineered E. coli for overexpression of 4HPA3H. The high-density fermentation of the engineered E. coli was conducted in a 5 L bioreactor. Subsequently, the conditions for whole-cell biocatalysis were optimized. The dry cell weight of the 4HPA3H-expressed strain reached 34.80 g/L. After incubated in the bioreactor for 6 h, 18.74 g/L (0.85 g/(L·OD₆₀₀)) of caffeic acid was obtained, with a conversion rate of 78.81% achieved. To the best of our knowledge, the titer of caffeic acid is the highest reported to date. The high-density fermentation of E. coli for overexpression of 4HPA3H and the efficient biosynthesis of caffeic acid may facilitate future large-scale production of caffeic acid.
Caffeic Acids ; Escherichia coli/metabolism* ; Fermentation ; Metabolic Engineering ; Mixed Function Oxygenases/metabolism* ; Phenylacetates

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*

Aims: Lytic polysaccharide monooxygenase (LPMO) is an enzyme capable of cleaving glycoside bonds of recalcitrant polysaccharides through an oxidative mechanism. LPMO activity, in synergy with hydrolytic enzymes, increases the production of monomer sugars from the biodegradation of lignocellulose. This study was aimed at evaluating actinomycete S2 strain LPMO activity based on the release of xylose as one of reducing sugar and hydrogen peroxide (H2O2) in the course of lignocellulosic biodegradation. Methodology and results: The oxidation activity of LPMO from actinomycete S2 strain was measured by using the substrate of Avicel supplemented with ascorbic acid and copper ions (Cu2+) to identify its effect on the release of xylose as one of reducing sugar. The optimum incubation time for the LPMO production was also conducted. Further, H2O2 quantitative analysis was performed as by-product of LPMO activity and 16S rRNA gene sequence of actinomycete S2 strain were subsequently determined. We found that supplementation of 1 mM ascorbic acid and 0.2 mM Cu2+ increased xylose as one of reducing sugar production by up to 5-fold from 255.03 to 1290 μg/mL after an optimal incubation period of 6 days. Based on H2O2 production, the LPMO activity of actinomycete S2 strain was 0.019 ± 0.001 U/mL. There is likelihood that LPMO activity derived from actinomycete S2 strain has a synergistic effect with the activity of other lignocellulose-degrading enzymes. This actinomycete showed 99% similarity to the 16S rRNA gene sequence of Streptomyces avermitilis strain EAAG80. Conclusion, significance, and impact of study LPMO enzyme activity from actinomycete S2 strain as determined by the production of reducing sugar and H2O2 was greatly increased by supplementation with ascorbic acid as an electron donor and Cu2+ ions. To the best of our knowledge, this is the first elucidation of LPMO activity from an indigenous Indonesian actinomycete.
Mixed Function Oxygenases--metabolism ; Lignin--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