Recombinant expression and in vitro activity identification of a bioactive peptide QUB2984 from skin secretion of Agalychnis callidryas / 中国组织工程研究

BACKGROUND:Frog active peptides have rich activities,such as antibacterial and anti-tumor,and are expected to solve the problem of antibiotic resistance. OBJECTIVE:The active peptide QUB2984 was discovered in the skin secretions of Agalychnis callidryas.Its structure and properties were simulated by bioinformatics.The peptide was synthesized,purified,and identified and its biological functions were investigated. METHODS:Agalychnis callidryas skin secretions were collected by electrostimulation.The sequence of QUB2984 was obtained through constructing a cDNA library with isolated mRNA.BLAST was used for peptide sequence alignment.Besides that,Iterative Threading ASSEmbly Refinement(I-TASSER)and HeliQuest tools were used for protein secondary structure simulation.It was synthesized by solid-phase peptide synthesis,purified by reverse-phase high-performance liquid chromatography,and structurally confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.The purified peptide was used to evaluate its biological activity.Its antibacterial effect was evaluated by the minimum inhibitory concentration method.Its cytotoxic effect was detected by MTT assay.Its safety was investigated by a hemolysis test. RESULTS AND CONCLUSION:(1)Peptide QUB2984 had basically α-spiral structure,with a relatively intact hydrophobic surface,and a certain destructive ability to biofilm.The third amino acid position of QUB2984 was composed of W and had a G-X-G structure.(2)The minimum inhibitory concentration of QUB2984 against gram-positive Staphylococcus aureus was 2 μmol/L,the minimum inhibitory concentration against gram-negative Escherichia coli was 2 μmol/L,and the minimum inhibitory concentration against the fungus Candida albicans was 8 μmol/L.(3)The active peptide QUB2984 had obvious inhibitory effect on human non-small cell lung cancer cells NCI-H838 at 10-5 mol/L concentration,and the hemolytic effect on horse red cells at 64 μmol/L concentration was 50%.(4)The results showed that QUB2984 had anti-bacterial and anti-cancer activity,and it had a positive charge of +3,which was conducive to contact with bacteria or cells.

Effect of Naozhenning Granules on Energy Metabolism of Cortical Mitochondria in Rat Model of Post-concussion Syndrome / 中国实验方剂学杂志

ObjectiveTo explore the effects of Naozhenning granules on the memory function and neuron cells in the rat model of post-concussion syndrome based on mitochondrial biosynthesis. MethodSPF-grade Wistar rats were used to establish the multiple cerebral concussion （MCC） model by the weight-drop method. The successfully modeled rats were assigned into model， piracetam （0.324 g·kg-1）， and low-， medium-， and high-dose （2.25， 4.5， and 9 g·kg-1， respectively） Naozhenning groups. The rats were administrated with corresponding drugs by gavage and those in the blank group and model group were administrated the same volume of normal saline once a day for 14 days. The general state of rats was observed before and after treatment. The open field test and new object recognition test were conducted to examine the motor and memory abilities of rats. Hematoxylin-eosin staining was employed to observe the pathological changes of cortical neurons in rats. Western blot and real-time polymerase chain reaction were employed to determine the protein and mRNA levels， respectively， of peroxisome proliferator-activated receptor γ-coactivator-1α （PGC-1α）， nuclear respiratory factor-1 （NRF-1）， and transcription factor A mitochondrial （TFAM） in rat cortex. ResultCompared with the blank group， the model group showed anxious and manic mental status， yellow and messy fur， and reduced food intake. In the open field experiment， the model group showed reduced total movement distance， times of entering the central grid， and times of rearing decreased and increased resting time compared with the blank group （P<0.01）. The model group had lower recognition index of new objects than the blank group （P<0.01）. In addition， the modeling caused reduced neurons with sparse distribution and deformed， broken， and irregular nucleoli and down-regulated the mRNA and protein levels of PGC-1α， NRF-1， and TFAM in the cortex （P<0.01）. Compared with the model group， piracetam and Naozhenning improved the mental state， coat color， food intake， and activities of rats. In the open field test， piracetam and Naozhenning increased the total movement distance， the times of entering the central grid， and the times of rearing and shortened the resting time （P<0.05， P<0.01）. The piracetam and Naozhenning groups had higher recognition index of new objects than the model group （P<0.05， P<0.01）. Compared with the model group， the piracetam and Naozhenning groups showed increased neurons with tight arrangement and large and round nuclei， and some cells with irregular morphology and turbid cytoplasm. Furthermore， piracetam and medium-dose Naozhenning upregulated the protein levels of PGC-1α， NRF-1， and TFAM （P<0.01）. Low-dose Naozhenning upregulated the protein levels of NRF-1 and TFAM （P<0.01）， and high-dose Naozhenning upregulated the protein levels of PGC-1α and TFAM in the cortex （P<0.01）. The mRNA levels of PGC-1α， NRF-1， and TFAM in the cortex were upregulated in the piracetam group and Naozhenning groups （P<0.05， P<0.01）. ConclusionNaozhenning granules can improve the motor， memory， and learning， repair the neuronal damage， and protect the nerve function in the rat model of MCC by promoting mitochondrial biosynthesis.

Research Progress on Mechanism of Action of DHODH in Progression of Malignant Tumors / 肿瘤防治研究

Dihydroorotate dehydrogenase (DHODH) is a flavin-dependent metabolic enzyme that oxidizes dihydroorotate acid to orotic acid in the de novo synthesis pathway of pyrimidine metabolism. DHODH is located in mitochondria, closely related to cellular oxidative phosphorylation, and an important suppressor of the ferroptosis pathway. This study investigates the influence of DHODH on the progression of malignant tumors, including its important role in the de novo synthesis of pyrimidine, oxidative phosphorylation, and ferroptosis. The objective is to present evidence that DHODH is a potential target for the clinical treatment of tumors.

The biotin synthesis pathway in Mycobacteria tuberculosis is a new target for the development of anti-tuberculosis drugs / 药学学报

italic>Mycobacterium tuberculosis, responsible for tuberculosis (TB), remains a major health problem worldwide and is one of the infectious diseases causing increased morbidity and mortality worldwide. Biotin, namely vitamin H, is an important cofactor necessary for fatty acid biosynthesis, gluconeogenesis and amino acid metabolism in organisms including Mycobacterium tuberculosis. Due to its inability to ingestion biotin from outside, Mycobacterium tuberculosis can only obtain biotin through biotin biosynthesis. Different from the classical BioC-BioH, BioI-BioW and non-classical BioZ pathways, Mycobacterium tuberculosis synthesized biotin by "BioC-BioH(2)" pathway in the early stage. This review focuses on the unique biotin synthesis pathway of Mycobacterium tuberculosis and its key genes, especially the response of this pathway and biotin-dependent carboxylase to tuberculosis first-and second-line drugs, as well as inhibitors and natural products targeting biotin synthesis.

Analysis of phenotype formation mechanism of a new variety of Lonicera japonica Flos "Huajin 6" at long bud stage / 药学学报

Based on the long bud stage phenotype of a new Lonicera japonica Flos variety "Huajin 6", using "Huajin 6" and "Da Mao Hua" as materials, probing the mechanism of its phenotype formation. Detection of endogenous Jasmonic acid hormones (JAs) content; the genes related to jasmonic acid (JA) synthesis were identified by transcriptome analysis of Lonicera japonica; flower buds and flowers of "Huajin 6" and "Da Mao Hua" were collected at different periods, and the qRT-PCR (quantitative real-time PCR) technique was used to analyze the trend of the expression of synthesis-related enzyme genes in Lonicera japonica Flos during the bud stage. The study found that the content of JAs in "Huajin 6" Lonicera japonica Flos was significantly lower than that in "Da Mao Hua"; applying exogenous methyl-jasmonate (MeJA) to "Huajin 6" can restore its flowering phenotype, making it close to wild type Lonicera japonica Flos; there are significant differences in the expression of two allene oxide synthase genes (AOS), three lipoxygenase genes (LOX), and two allene oxide cyclase genes (AOC) in the flowers and buds of "Huajin 6" and "Da Mao Hua" at different periods. It is hypothesized that the low expression of JA synthesis-related enzyme genes in " Huajin 6" leads to the blockage of JA synthesis, which causes the formation of the long bud phenotype. This study laid a certain foundation for the genetic breeding of Lonicera japonica, provided a new idea for the improvement of Lonicera japonica varieties, and provided a reference for the study of JAs in plant flower organs.

Research progress on the role of cytochrome P450 in plant sesquiterpene biosynthesis / 药学学报

Sesquiterpenes are natural terpenoids with 15 carbon atoms in the basic skeleton, which mainly exist in plant volatile oil and have important physiological and medicinal value. Cytochrome P450 (CYP450) is a kind of monooxygenase encoded by supergene family, which is one of the largest gene families in plants. It is involved in the synthesis and metabolism of terpenoids, alkaloids and other secondary metabolites. In the process of terpene biosynthesis, CYP450 participates in the post-modification stage of terpenes by introducing functional groups such as hydroxyl, carboxyl and carbonyl, which plays an important role in enriching the diversity of terpenes. The CYP450 enzymes involved in sesquiterpene synthesis and their substrate catalytic specificity mechanisms have been partially investigated. In this paper, the biosynthetic pathway of plant sesquiterpenes, the structure and classification of CYP450 enzymes were briefly introduced, and the CYP450 enzymes involved in sesquiterpene biosynthesis were summarized, in order to provide a reference for intensive study of the role of CYP450 enzymes in the synthesis of sesquiterpenoids.

Genomics-driven derivatization of the bioactive fungal sesterterpenoid variecolin: Creation of an unnatural analogue with improved anticancer properties

A biosynthetic gene cluster for the bioactive fungal sesterterpenoids variecolin ( 1) and variecolactone ( 2) was identified in Aspergillus aculeatus ATCC 16872. Heterologous production of 1 and 2 was achieved in Aspergillus oryzae by expressing the sesterterpene synthase VrcA and the cytochrome P450 VrcB. Intriguingly, the replacement of VrcB with homologous P450s from other fungal terpenoid pathways yielded three new variecolin analogues ( 5- 7). Analysis of the compounds' anticancer activity in vitro and in vivo revealed that although 5 and 1 had comparable activities, 5 was associated with significantly reduced toxic side effects in cancer-bearing mice, indicating its potentially broader therapeutic window. Our study describes the first tests of variecolin and its analogues in animals and demonstrates the utility of synthetic biology for creating molecules with improved biological activities.

Disulfide bridge-targeted metabolome mining unravels an antiparkinsonian peptide

Peptides are a particular molecule class with inherent attributes of some small-molecule drugs and macromolecular biologics, thereby inspiring continuous searches for peptides with therapeutic and/or agrochemical potentials. However, the success rate is decreasing, presumably because many interesting but less-abundant peptides are so scarce or labile that they are likely 'overlooked' during the characterization effort. Here, we present the biochemical characterization and druggability improvement of an unprecedented minor fungal RiPP (ribosomally synthesized and post-translationally modified peptide), named acalitide, by taking the relevant advantages of metabolomics approach and disulfide-bridged substructure which is more frequently imprinted in the marketed peptide drug molecules. Acalitide is biosynthetically unique in the macrotricyclization via two disulfide bridges and a protease (AcaB)-catalyzed lactamization of AcaA, an unprecedented precursor peptide. Such a biosynthetic logic was successfully re-edited for its sample supply renewal to facilitate the identification of the in vitro and in vivo antiparkinsonian efficacy of acalitide which was further confirmed safe and rendered brain-targetable by the liposome encapsulation strategy. Taken together, the work updates the mining strategy and biosynthetic complexity of RiPPs to unravel an antiparkinsonian drug candidate valuable for combating Parkinson's disease that is globally prevailing in an alarming manner.

Role and Possible Mechanism of Clock Gene Rev-erbα in Exercise-induced Mitochondrial Biogenesis / 生物化学与生物物理进展

The clock gene Rev-erbα, also known as nuclear receptor subfamily 1 group D member 1 (Nr1d1), is a crucial regulatory factor in organisms. It exhibits circadian rhythmic expression in metabolically active tissues such as skeletal muscles, heart, liver, and adipose tissue, responding to various environmental stimuli. Rev-erbα plays a significant role in regulating circadian rhythms, metabolic homeostasis, and other physiological processes, earning its designation as an “integrator” of the circadian system and metabolism. Rev-erbα establishes complex connections with other clock genes through the transcriptional-translational feedback loop (TTFL), which is important for the rhythmic output of biological clock system and for the relative stability of phases and cycles. Mitochondrial biogenesis is a physiological process initiated by cells to maintain energy homeostasis by using existing mitochondria as a template for self-growth and division. As the “energy factory” of organism, disruptions in mitochondrial biogenesis are closely associated with the development of various diseases. Studies have shown that not only the factors involved in mitochondrial biogenesis have circadian oscillations, but also the morphology, dynamics and energy metabolism of mitochondria themselves have cyclic fluctuations throughout the day, suggesting that mitochondrial biogenesis is regulated by the biological clock system, in which the clock gene Rev-erbα plays a key role, it drives mitochondrial biogenesis and synergistically regulates autophagy to normalize a number of physiological processes in the body. Rev-erbα is sensitive to both internal and external environmental changes, and disruptions in circadian rhythms, metabolic diseases, and aging are significant inducers of changes in Rev-erbα expression, and its concomitant inflammation and oxidative stress may be an intrinsic mechanism for inhibiting mitochondrial biogenesis. Therefore, the enhancement of mitochondrial biogenesis by regulating the Rev-erbα activity status may be an important way to improve the pathology and promote the health of organism. Exercise, as a commonly accepted non-pharmacological tool, plays an important role in enhancing mitochondrial biogenesis and promoting health. It has been found that there is a close relationship between exercise and Rev-erbα. On the one hand, exercise stimulation directly affects the expression of Rev-erbα, especially high-intensity and long-term regular exercise; on the other hand, Rev-erbα achieves indirect regulation of exercise capacity by mediating processes such as skeletal muscle mitochondrial biogenesis and autophagy, muscle mass maintenance, energy metabolism and skeletal muscle regeneration. Based on the above findings, it is hypothesized that Rev-erbα may serve as a key bridge between exercise and mitochondrial biogenesis. Exercise enhances the transcriptional response of Rev-erbα in the nucleus, upregulates the expression of Rev-erbα protein in cytoplasm, activates the AMP-activated proteinkinase (AMPK)/ silent information regulator 1 (SIRT1)/peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) pathway, regulates Ca2+ flux and downstream signaling molecules; meanwhile, exercise can upregulate antioxidant gene expression and alleviate oxidative stress through Rev-erbα, which ultimately enhances the function of mitochondria, and promotes mitochondrial biogenesis. In conclusion, the clock gene Rev-erbα emerges as a crucial target for exercise-induced enhancement of mitochondrial biogenesis. In this paper, the biological characteristics ofRev-erbα, the role of Rev-erbα in regulating mitochondrial biogenesis and the factors that may influence it, the interaction between exercise and Rev-erbα, and the potential mechanism of exercise-induced mitochondrial biogenesis via Rev-erbα are sorted out and discussed, which can provide theoretical references to the mechanism of exercise-promoted mitochondrial biogenesis.

Bioinformatics Reveals Mechanism of Zuoguiwan in Treating Polycystic Ovary Syndrome / 中国实验方剂学杂志

ObjectiveTo explore the potential mechanism of Zuoguiwan in ameliorating polycystic ovary syndrome （PCOS） by network pharmacology and liquid chromatography-mass spectrometry （LC-MS）-based metabolomics. MethodThe active ingredients and potential targets of Zuoguiwan for treating PCOS were predicted by bioinformatics. SD rats were assigned into a control group and a modeling group. The rat model of PCOS was established by gavage with letrozole （1 mg·kg-1） combined with feeding with a high-fat diet. At the end of modeling， the modeled rats were assigned into model （normal saline）， metformin （300 mg·kg-1）， and Zuoguiwan （concentrate 1.62 g·kg-1） groups. The body weight and oestrous cycle of each rat were recorded， and the ovary was stained with hematoxylin and eosin for observation of ovarian morphology. Enzyme-linked immunosorbent assay was employed to determine the serum levels of follicle-stimulating hormone （FSH）， luteinizing hormone （LH）， anti-mullerian hormone （AMH）， testosterone （T）， and estradiol （E2）， and the LH/FSH ratio was calculated. Serum metabolomics of rats was conducted by orthogonal partial least squares-discriminant analysis （OPLS-DA） to screen the metabolite-enriched pathways. Furthermore， network pharmacology and association analysis were employed construct the compound-response-enzyme-gene network. ResultA total of 503 potential targets of Zuoguiwan and 5 843 targets of PCOS were screened out， with 271 common targets. The Gene Ontology enrichment analysis revealed that the common targets were involved in the response to lipopolysaccharide， etc.， and the Kyoto Encyclopedia of Genes and Genomes （KEGG） enrichment yielded 119 pathways. Animal experiments showed that compared with the control group， the model group presented increased body weight （P<0.01）， elevated LH and AMH levels （P<0.01）， increased LH/FSH ratio （P<0.01）， lowered E2 level （P<0.01）， and increased cystic follicles. Compared with the model group， Zuoguiwan and metformin decreased the body weight （P<0.01）， reduced atretic follicles and cystic follicles， increased mature follicles and corpus luteum， and thickened the granulosa layer. Moreover， Zuoguiwan lowered the T， FSH， LH， and AMH， and LH/FSH levels （P<0.01） and elevated the E2 level （P<0.01）. The principal component analysis and OPLS-DA in metabolomics showed that the differential metabolites between Zuoguiwan and model groups included 26 up-regulated metabolites in the Zuoguiwan group. There were 8 common pathways predicted by the KEGG enrichment analysis in network pharmacology and the metabolite enrichment in metabolomics. The results of topological analysis revealed the pathways of steroid hormone biosynthesis and glycerol-phospholipid metabolism， and the constructed compound-response-enzyme-gene network revealed that the key targets were protein kinase B1 （Akt1）， epithelial growth factor receptor （EGFR）， prostaglandin-endoperoxide synthase 2 （PTGS2）， and mitogen-activated protein kinase 1 （MAPK1）. ConclusionZuoguiwan regulated the steroid hormone biosynthesis pathway to recover hormone levels， promote follicle production and development， and improve ovarian function， which may be the potential mechanism of this medicine in treating PCOS.

Absence of trehalose synthesis in Acidithiobacillus ferrooxidans ATCC 23270 and Acidithiobacillus ferrivorans CF27 at low temperature

Trehalose is a type of carbohydrate that protects against different types of stress and is also used as a source of carbon storage in prokaryotes. There are four different ways of synthesizing trehalose in Acidithiobacillus ferrivorans and two in Acidithiobacillus ferrooxidans, but its purpose remains unknown. This study aimed to measure the production of trehalose under different conditions by quantifying it in three culture media at two different temperatures. The growth kinetics of both species were also assessed, and the trehalose concentration was analysed during the early stationary phase using an enzymatic method. The results showed that the modified 9K medium with ferrous iron at 28°C had the highest production of trehalose, with A. ferrivorans CF27 having a higher production of 0.34 µmol/mg protein compared to A. ferrooxidans ATCC 23270 at 0.31 µmol/mg protein. When using CuS, the production of trehalose was lower, with 0.02 and 0.03 µmol/mg protein for A. ferrivorans CF27 and A. ferrooxidans ATCC 23270, respectively, while no trehalose was detected in the presence of zinc. At 15°C, the enzymatic method did not detect any trehalose in all three culture media, this would indicate that this carbohydrate does not protect against low temperatures in either species.

La trehalosa es un tipo de carbohidrato, que en procariotas protege contra diferentes tipos de estrés y también se utiliza como fuente de almacenamiento de carbono. Hay cuatro formas diferentes de sintetizar trehalosa en Acidithiobacillus ferrivorans y dos en Acidithiobacillus ferrooxidans, pero su propósito sigue siendo desconocido. Este estudio tuvo como objetivo medir la producción de trehalosa en diferentes condiciones mediante su cuantificación en tres medios de cultivo a dos temperaturas diferentes. También se evaluó la cinética de crecimiento de ambas especies y se analizó la concentración de trehalosa durante la fase estacionaria temprana mediante un método enzimático. Los resultados mostraron que el medio 9K modificado con hierro ferroso a 28 °C tuvo la mayor producción de trehalosa, con A. ferrivorans CF27 con una mayor producción de 0.34 µmol/mg de proteína en comparación con A. ferrooxidans ATCC 23270 a 0.31 µmol/mg de proteína. Al utilizar CuS, la producción de trehalosa fue menor, con 0.02 y 0.03 µmol/mg de proteína para A. ferrivorans CF27 y A. ferrooxidans ATCC 23270, respectivamente, mientras que en presencia de zinc no se detectó trehalosa. A 15°C, el método enzimático no detectó trehalosa en los tres medios de cultivo, lo que indicaria que este carbohidrato no protege contra las bajas temperaturas en ninguna de las especies.

Research progress on triterpenoids of Betula plants / 药学学报

The secondary metabolites of plants are important sources of natural drugs. Betula plants have abundant pharmacological value, complex mechanism and wide applications, which are closely related to the triterpenoids of theirs. Triterpenoids in Betula species are mainly divided into dammarane-type, ocotillol-type, oleanane-type, lupane-type and cycloaltunane-type. The extracts of Betula species have varieties of activities such as anti-tumor, anti-inflammatory, anti-oxidant, anti-bacterial, etc. And the biosynthetic pathways of triterpenoids after 2,3-oxidosqualene are split into four branches of dammarenediol-II, lupeol, cycloartenol and amyrin according to the different oxidosqualene cyclases. This review summarizes the chemical constituents, pharmacological activities and biosynthetic pathways of triterpenoids in Betula plants. It provides a reference for the research and development of new drugs and the production of these triterpenoids in microbial cell factories by synthetic biology methods.

Advances on the production of organic acids by yeast / 生物工程学报

Organic acids are organic compounds that can be synthesized using biological systems. They often contain one or more low molecular weight acidic groups, such as carboxyl group and sulphonic group. Organic acids are widely used in food, agriculture, medicine, bio-based materials industry and other fields. Yeast has unique advantages of biosafety, strong stress resistance, wide substrate spectrum, convenient genetic transformation, and mature large-scale culture technology. Therefore, it is appealing to produce organic acids by yeast. However, challenges such as low concentration, many by-products and low fermentation efficiency still exist. With the development of yeast metabolic engineering and synthetic biology technology, rapid progress has been made in this field recently. Here we summarize the progress of biosynthesis of 11 organic acids by yeast. These organic acids include bulk carboxylic acids and high-value organic acids that can be produced naturally or heterologously. Finally, future prospects in this field were proposed.

Advances in the production of chemicals by organelle compartmentalization in Saccharomyces cerevisiae / 生物工程学报

As a generally-recognized-as-safe microorganism, Saccharomyces cerevisiae is a widely studied chassis cell for the production of high-value or bulk chemicals in the field of synthetic biology. In recent years, a large number of synthesis pathways of chemicals have been established and optimized in S. cerevisiae by various metabolic engineering strategies, and the production of some chemicals have shown the potential of commercialization. As a eukaryote, S. cerevisiae has a complete inner membrane system and complex organelle compartments, and these compartments generally have higher concentrations of the precursor substrates (such as acetyl-CoA in mitochondria), or have sufficient enzymes, cofactors and energy which are required for the synthesis of some chemicals. These features may provide a more suitable physical and chemical environment for the biosynthesis of the targeted chemicals. However, the structural features of different organelles hinder the synthesis of specific chemicals. In order to ameliorate the efficiency of product biosynthesis, researchers have carried out a number of targeted modifications to the organelles grounded on an in-depth analysis of the characteristics of different organelles and the suitability of the production of target chemicals biosynthesis pathway to the organelles. In this review, the reconstruction and optimization of the biosynthesis pathways for production of chemicals by organelle mitochondria, peroxisome, golgi apparatus, endoplasmic reticulum, lipid droplets and vacuole compartmentalization in S. cerevisiae are reviewed in-depth. Current difficulties, challenges and future perspectives are highlighted.

Research progress on chemical structures and pharmacological effects of natural cytisine and its derivatives / 中国中药杂志

Cytisine derivatives are a group of alkaloids containing the structural core of cytisine, which are mainly distributed in Fabaceae plants with a wide range of pharmacological activities, such as resisting inflammation, tumors, and viruses, and affecting the central nervous system. At present, a total of 193 natural cytisine and its derivatives have been reported, all of which are derived from L-lysine. In this study, natural cytisine derivatives were classified into eight types, namely cytisine type, sparteine type, albine type, angustifoline type, camoensidine type, cytisine-like type, tsukushinamine type, and lupanacosmine type. This study reviewed the research progress on the structures, plant sources, biosynthesis, and pharmacological activities of alkaloids of various types.

Advances in physiological activities and synthesis of β-nicotinamide mononucleotide / 生物工程学报

Nicotinamide mononucleotide (NMN) is one of the key precursors of coenzyme Ⅰ (NAD+). NMN exists widely in a variety of organisms, and β isomer is its active form. Studies have shown that β-NMN plays a key role in a variety of physiological and metabolic processes. As a potential active substance in anti-aging and improving degenerative and metabolic diseases, the application value of β-NMN has been deeply explored, and it is imminent to achieve large-scale production. Biosynthesis has become the preferred method to synthesize β-NMN because of its high stereoselectivity, mild reaction conditions, and fewer by-products. This paper reviews the physiological activity, chemical synthesis as well as biosynthesis of β-NMN, highlighting the metabolic pathways involved in biosynthesis. This review aims to explore the potential of improving the production strategy of β-NMN by using synthetic biology and provide a theoretical basis for the research of metabolic pathways as well as efficient production of β-NMN.

Genome-wide analysis of AP2/ERF superfamily in Isatis indigotica / 中西医结合学报

OBJECTIVE@#AP2/ERF (APETALA2/ethylene-responsive factor) superfamily is one of the largest gene families in plants and has been reported to participate in various biological processes, such as the regulation of biosynthesis of active lignan. However, few studies have investigated the genome-wide role of the AP2/ERF superfamily in Isatis indigotica. This study establishes a complete picture of the AP2/ERF superfamily in I. indigotica and contributes valuable information for further functional characterization of IiAP2/ERF genes and supports further metabolic engineering.@*METHODS@#To identify the IiAP2/ERF superfamily genes, the AP2/ERF sequences from Arabidopsis thaliana and Brassica rapa were used as query sequences in the basic local alignment search tool. Bioinformatic analyses were conducted to investigate the protein structure, motif composition, chromosome location, phylogenetic relationship, and interaction network of the IiAP2/ERF superfamily genes. The accuracy of omics data was verified by quantitative polymerase chain reaction and heatmap analyses.@*RESULTS@#One hundred and twenty-six putative IiAP2/ERF genes in total were identified from the I. indigotica genome database in this study. By sequence alignment and phylogenetic analysis, the IiAP2/ERF genes were classified into 5 groups including AP2, ERF, DREB (dehydration-responsive element-binding factor), Soloist and RAV (related to abscisic acid insensitive 3/viviparous 1) subfamilies. Among which, 122 members were unevenly distributed across seven chromosomes. Sequence alignment showed that I. indigotica and A. thaliana had 30 pairs of orthologous genes, and we constructed their interaction network. The comprehensive analysis of gene expression pattern in different tissues suggested that these genes may play a significant role in organ growth and development of I. indigotica. Members that may regulate lignan biosynthesis in roots were also preliminarily identified. Ribonucleic acid sequencing analysis revealed that the expression of 76 IiAP2/ERF genes were up- or down-regulated under salt or drought treatment, among which, 33 IiAP2/ERF genes were regulated by both stresses.@*CONCLUSION@#This study undertook a genome-wide characterization of the AP2/ERF superfamily in I. indigotica, providing valuable information for further functional characterization of IiAP2/ERF genes and discovery of genetic targets for metabolic engineering.

Late-stage cascade of oxidation reactions during the biosynthesis of oxalicine B in Penicillium oxalicum

Oxalicine B ( 1) is an α-pyrone meroterpenoid with a unique bispirocyclic ring system derived from Penicillium oxalicum. The biosynthetic pathway of 15-deoxyoxalicine B ( 4) was preliminarily reported in Penicillium canescens, however, the genetic base and biochemical characterization of tailoring reactions for oxalicine B ( 1) has remained enigmatic. In this study, we characterized three oxygenases from the metabolic pathway of oxalicine B ( 1), including a cytochrome P450 hydroxylase OxaL, a hydroxylating Fe(II)/α-KG-dependent dioxygenase OxaK, and a multifunctional cytochrome P450 OxaB. Intriguingly, OxaK can catalyze various multicyclic intermediates or shunt products of oxalicines with impressive substrate promiscuity. OxaB was further proven via biochemical assays to have the ability to convert 15-hydroxdecaturin A ( 3) to 1 with a spiro-lactone core skeleton through oxidative rearrangement. We also solved the mystery of OxaL that controls C-15 hydroxylation. Chemical investigation of the wild-type strain and deletants enabled us to identify 10 metabolites including three new compounds, and the isolated compounds displayed potent anti-influenza A virus bioactivities exhibiting IC50 values in the range of 4.0-19.9 μmol/L. Our studies have allowed us to propose a late-stage biosynthetic pathway for oxalicine B ( 1) and create downstream derivatizations of oxalicines by employing enzymatic strategies.

Functional characterization of a cycloartenol synthase and four glycosyltransferases in the biosynthesis of cycloastragenol-type astragalosides from Astragalus membranaceus

Astragalosides are the main active constituents of traditional Chinese medicine Huang-Qi, of which cycloastragenol-type glycosides are the most typical and major bioactive compounds. This kind of compounds exhibit various biological functions including cardiovascular protective, neuroprotective, etc. Owing to the limitations of natural sources and the difficulties encountered in chemical synthesis, re-engineering of biosynthetic machinery will offer an alternative and promising approach to producing astragalosides. However, the biosynthetic pathway for astragalosides remains elusive due to their complex structures and numerous reaction types and steps. Herein, guided by transcriptome and phylogenetic analyses, a cycloartenol synthase and four glycosyltransferases catalyzing the committed steps in the biosynthesis of such bioactive astragalosides were functionally characterized from Astragalus membranaceus. AmCAS1, the first reported cycloartenol synthase from Astragalus genus, is capable of catalyzing the formation of cycloartenol; AmUGT15, AmUGT14, AmUGT13, and AmUGT7 are four glycosyltransferases biochemically characterized to catalyze 3-O-xylosylation, 3-O-glucosylation, 25-O-glucosylation/O-xylosylation and 2'-O-glucosylation of cycloastragenol glycosides, respectively. These findings not only clarified the crucial enzymes for the biosynthesis and the molecular basis for the structural diversity of astragalosides in Astragalus plants, also paved the way for further completely deciphering the biosynthetic pathway and constructing an artificial pathway for their efficient production.

Insights into the biosynthesis of septacidin l-heptosamine moiety unveils a VOC family sugar epimerase

l-Heptopyranoses are important components of bacterial polysaccharides and biological active secondary metabolites like septacidin (SEP), which represents a group of nucleoside antibiotics with antitumor, antifungal, and pain-relief activities. However, little is known about the formation mechanisms of those l-heptose moieties. In this study, we deciphered the biosynthetic pathway of the l,l-gluco-heptosamine moiety in SEPs by functional characterizing four genes and proposed that SepI initiates the process by oxidizing the 4'-hydroxyl of l-glycero-α-d-manno-heptose moiety of SEP-328 ( 2) to a keto group. Subsequently, SepJ (C5 epimerase) and SepA (C3 epimerase) shape the 4'-keto-l-heptopyranose moiety by sequential epimerization reactions. At the last step, an aminotransferase SepG installs the 4'-amino group of the l,l-gluco-heptosamine moiety to generate SEP-327 ( 3). An interesting phenomenon is that the SEP intermediates with 4'-keto-l-heptopyranose moieties exist as special bicyclic sugars with hemiacetal-hemiketal structures. Notably, l-pyranose is usually converted from d-pyranose by bifunctional C3/C5 epimerase. SepA is an unprecedented monofunctional l-pyranose C3 epimerase. Further in silico and experimental studies revealed that it represents an overlooked metal dependent-sugar epimerase family bearing vicinal oxygen chelate (VOC) architecture.