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Abscisic acid, a plant hormone that inhibits growth, is a key factor in balancing plant endogenous hormones and regulating growth and metabolism. Abscisic acid can improve the drought resistance and salt tolerance of crops, reduce fruit browning, reduce the incidence rate of malaria and stimulate insulin secretion, so it has a broad application potential in agriculture and medicine. Compared with traditional plant extraction and chemical synthesis, abscisic acid synthesis by microorganisms is an economic and sustainable route. At present, a lot of progress has been made in the synthesis of abscisic acid by natural microorganisms such as Botrytis cinerea and Cercospora rosea, while the research on the synthesis of abscisic acid by engineered microorganisms is rarely reported. Saccharomyces cerevisiae, Yarrowia lipolytica and Escherichia coli are common hosts for heterologous synthesis of natural products due to their advantages of clear genetic background, easy operation and friendliness for industrial production. Therefore, the heterologous synthesis of abscisic acid by microorganisms is a more promising production method. The author reviews the research on the heterologous synthesis of abscisic acid by microorganisms from five aspects: selection of chassis cells, screening and expression enhancement of key enzymes, regulation of cofactors, enhancement of precursor supply and promotion of abscisic acid efflux. Finally, the future development direction of this field is prospected.
Subject(s)
Abscisic Acid/metabolism , Plant Growth Regulators/metabolism , Plants/metabolism , Yarrowia/metabolismABSTRACT
Constraint-based genome-scale metabolic network models (genome-scale metabolic models, GEMs) have been widely used to predict metabolic phenotypes. In addition to stoichiometric constraints, other constraints such as enzyme availability and thermodynamic feasibility may also limit the cellular phenotype solution space. Recently, extended GEM models considering either enzymatic or thermodynamic constraints have been developed to improve model prediction accuracy. This review summarizes the recent progresses on metabolic models with multiple constraints (MCGEMs). We presented the construction methods and various applications of MCGEMs including the simulation of gene knockout, prediction of biologically feasible pathways and identification of bottleneck steps. By integrating multiple constraints in a consistent modeling framework, MCGEMs can predict the metabolic bottlenecks and key controlling and modification targets for pathway optimization more precisely, and thus may provide more reliable design results to guide metabolic engineering of industrially important microorganisms.
Subject(s)
Genome , Metabolic Engineering , Metabolic Networks and Pathways/genetics , Models, Biological , ThermodynamicsABSTRACT
Retinal metabolism includes material metabolism and energetic metabolism.Retina is one of the most energy-consuming nerve tissue in human body and mainly relies on glycolysis for energy production, which is similar to very fast-growing tumor tissue.This process is known as Warburg effect.Warburg effect is of great significance, which is demonstrated that glucose is metabolized via glycolysis in a more rapid approach in comparison with oxidative phosphorylation pathway.In addition, glucose also supplies neoplastic tissue with carbon source or metabolic intermediates due to biosynthesis.The produced energy of retina is a summation of different retinal cells and tissue, such as photoreceptors, retinal pigment epithelium (RPE), Müller cells and retinal capillary endothelial cells etc.To understand the underlying mechanism contributing to Warburg effect and provide insight into metabolic coupling between neuron and glia is of important significance.Since key glycolysis enzymes (HK2, PFKFB3 and PKM2) take a pivotal role in controlling retinal cell proliferation and neovascularization, bioenergetic strategy targeting these enzymes suggests new idea in the treatment of retinal diseases where energy failure is part of the pathogenesis.Investigating underlying mechanism of retinal energy metabolism can provide new ideas for the treatment of age-related macular degeneration (AMD) and other diseases related to disordered retinal energy metabolism.The Warburg effect of retinal energetic metabolism and its regulatory mechanism were reviewed in this article.
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Objective:To study the dynamic changes of the pharmacodynamic components of Scutellaria baicalensis in the harvest period and the effects of ecological factors and key enzyme expression on it. Methods :The artificial cultivated annual S. baicalensis was studied and the expression of nine key enzyme genes (PAL, C4H, 4CL, CHS, CHI, FNS, F6H, UBGAT, and GUS) in the roots of S. baicalensis were determined by real-time quantitative PCR. The content of four main flavonoids (baicalin, wogonoside, baicalein, and wogonin) in the roots was determined by HPLC. The meteorological data of S. baicalensis were collected by the ecological meteorological station. SPSS statistical software and DPS statistical software were used for data analysis. Results: The content of flavonoids of four monomers of annual S. baicalensis decreased slowly in autumn, so the best harvest time of S. baicalensis was in early September. The results of grey correlation analysis showed that the ecological factors affecting the four flavonoids were SWC, Max Ta, RH, and PAR. The expression of C4H and UBGAT genes had an important effect on the accumulation of flavonoids in the roots of S. baicalensis in autumn. Maximum rainfall intensity may indirectly affect the accumulation of the pharmacodynamic components of S. baicalensis by affecting the gene expression of key enzymes. Conclusion: The dynamic changes of four main flavonoids of annual S. baicalensis in autumn and the expression of key enzyme genes of S. baicalensis annual are clarified, providing the theoretical basis for the clarification of the physiological and ecological mechanism of the biosynthesis of S. baicalensis and the improvement of the quality of S. baicalensis.
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Objective: To select reference genes suitable for the expression analysis of Bupleurum chinense, and analyze the relationship between the content of saikosaponin and the gene expression of key enzymes in different tissues of B. chinense. Methods The roots, stems, leaves and fruits of B. chinense were used as test materials, and five commonly used internal reference genes of Actin, α-tubublin, β-tubulin, Cyclophilin and EF-1α were selected as candidates by real-time quantitative PCR. Based on the selected internal reference gences, tissue expression pattern of ACAT, FPS, HMGR, IPPI, PMD, PMK, SE, SS, β-AS, UGT1, UGT3, UGT6, UGT8, UGT10, P450-7 and P450-12 genes in B. chinense was analyzed. The content of saikosaponin a, saikosaponin c and saikosaponin d were determined by HPLC, and correlation analysis was performed by SPSS. Results:The EF-1α gene with the best stability in the five candidate genes (EF-1α, Cyclophilin, Actin, β-tubulin, α-tubublin) was selected as the internal reference gene. The expression levels of 16 key enzymes in the roots of B. chinense were measured. The results showed that ACAT, PMK, IPPI, SS, SE, UGT1, UGT3, UGT6, and UGT8 were the highest in the aboveground parts, the levels of HMGR, β-AS, P450-7 and P450-12 were higher in the roots than those in the aboveground parts, but PMD, FPS and UGT10 were not significantly different in the tissues. The content of saponins in the root was much higher than that in the aerial parts (stem, leaf and fruit) by HPLC. The results of correlation analysis showed that 16 key enzyme genes in the upstream ACAT, HMGR, PMD, SE and so on were significantly correlated with downstream P450-7, P450-12, UGT3, UGT6 and UGT8 (P < 0.05). It showed that the key enzyme genes were closely related to each other and regulated the synthesis of saikosaponin in common. The correlation analysis between the 16 key enzyme genes and the content of saikosaponin showed: HMGR, P450-7, p450-12 and the total of three saponins were significantly positively correlated (P < 0.01), and β-AS was significantly correlated with the total content of three saponins (P < 0.05), and HMGR, P450-7, P450-12, and β-AS were significantly correlated with the monomer saponins a, c, d (P < 0.05). These four genes jointly regulated the synthesis of saikosaponin and had an important effect on the accumulation of saponin. Conclusion:The HMGR, β-AS, P450-7 and P450-12 genes in the saikosaponin synthesis pathway have a consistent distribution in saikosaponin synthesis and play an important role in the regulation of saponin synthesis.
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Objective: To select suitable references genes of Bupleurum scorzonerifolium for tissue expression analyses, and study the tissue expression characteristics of the key enzyme genes of saikosaponins biosynthesis. Methods: Five candidate reference genes including Actin, α-tubulin, β-tubulin, Cyclophilin, and EF-1α were chosen. The stability of these candidate reference genes was investigated by using four softwares (Delta CT, BestKeeper, NormFinder, and GeNorm). The stability of these candidate reference genes was tested and verified by real-time quantitative PCR. Used the stable reference gene, the tissue expression characteristics of the saikosaponins biosynthesis key enzyme genes (HMGR, IPPI, FPS, SS, and β-AS) was analyzed by qRT-PCR. Results: The average expression stability of the five candidate reference genes from high to low was β-tubulin > Cyclophilin > Actin > EF-1α > α-tubulin. Β-tubulin was the most suitable reference gene for tissue expression analysis in B. scorzonerifolium. HMGR expression level was roots > stems and fruits > leaves, IPPI expression level was roots > stems > fruits and leaves, FPS expression level was leaves > roots > stems and fruits, SS expression level was leaves > fruits > roots > stems, β-AS expression level was leaves > roots > fruits > stems. HMGR was significant positive correlated with IPPI, and FPS was significant positive correlated with β-AS (P < 0.05). Conclusion: β-tubulin gene was confirmed as the most suitable reference gene in different tissues of B. scorzonerifolium. It provided a methodological basis for the tissue expression analysis on the functional genes of B. scorzonerifolium. The expression pattern of five key enzyme genes of saikosaponins biosynthesis in different tissues had obvious differentiation, which might be involved in regulating the flow of saikosaponins synthesis and accumulation in various tissues of B. scorzonerifolium.
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Objective To compare and analyze the transcriptome of rhizome and leaves of Dioscorea zingiberensis, and excavate the key enzyme genes related to the saponin biosynthetic pathway in D. zingiberensis. Methods The transcriptome of rhizome and leaves of D. zingiberensis were sequenced by Illumina HiSeq2000 high-throughput sequencing technique. According to sequence annotate results to find the differentially expressed genes. Then the key enzyme genes related to the biosynthesis of diosgenin were identified according to the content of saponins in rhizomes and leaves of D. zingiberensis. The expression levels of some candidate genes were analyzed by real-time fluorescence quantitative PCR (qRT-PCR). Results A total of 81 660 Unigenes were gained and 64.33% of them were annotated in NT, NR, Swiss-Prot, KOG, GO, and KEGG databases. Based on their expression and KEGG annotation, totally 227 catalytic enzyme genes of 29 kinds that may participate in D. zingiberensis saponin biosynthetic pathway were screened. The expression pattern of some catalytic enzymes was correlated with the content of saponin. Also were found five D. zingiberensis endophyte genes. Conclusion This experiment obtained candidate key enzyme genes tentatively that involved in the biosynthesis of saponin. Some candidate enzyme genes may participate in the post-modification process of steroidal saponins in D. zingiberensis. In additon, it was found that D. zingiberensis endotrophic bacteria may be involved in the saponin biosynthesis. The results laid a foundation to further elucidate the molecular mechanism of sapogenin synthesis pathway.
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Nonsyndromic cleft of lip with or without palate ( NSCL/P ) is one of the most common congenital birth defects in the maxillofacial region and it is related to genetic factors and environment .Folic acid deficiency , metabolic disorder and the genetic polymorphisms of key metabolic enzymes may be the important factors contributing to NSCL /P .Maternal folic acid intake may reduce the risk of non syndrome cleft lip and palate .This article will review the relationship among the metabolism of folic acid , the genetic polymorphisms of key enzymes in folate metabolism and NSCL /P .
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Phenolic acids with significant biological activity and pharmacological effects are a class of active ingredients in the roots and rhizomes of Salvia miltiorrhiza used for the treatment of cardiovascular and cerebrovascular diseases. With increasing the demand of clinical and market, enhancing the contents and utilization efficiency of phenolic acids in the roots and rhizomes of S. miltiorrhiza has the important practical significance for sustainable development. In this paper, the research progress in study on genomics, proteomics, and metabonomics in recent years was carried out to summarize the biosynthesis pathway, key enzymes genes, regulation mechanism, and bioconversion and utilization of phenolic acids in the roots and rhizomes of S. miltiorrhiza, which lays the scientific foundation for the efficient production and comprehensive utilization of phenolic acids resources in S. miltiorrhiza.
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One strain of endophytic fungus ZPRa-R-1 was obtained for the capacity of promoting production of salidroside in Rhodiola crenulata. To explain the mechanism of salidroside biosynthesis in host plant, eight housekeeping genes were evaluated, and the evaluation method was created for the expression activities of four key enzyme genes PAL (phenylalanine ammonia-lyase), TyDC (tyrosine decarboxylase), TAT (tyrosine transaminase), UDPGT (UDP-glucosyltransferase) referenced double reference genes in biosynthesis pathway of salidroside in R. crenulata. Stabilities of housekeeping genes were confirmed by real-time fluorescent quantitative PCR technology and three softwares including geNorm, NormFinder and BestKeeper, then relative expressions of key enzyme genes were analysized by the 2-ΔΔCt method. The results showed that the most stable gene was GAPDH, followed by PCS, and the most appropriate reference of internal genes were combination with two genes in R. crenulata inoculated with endophytic fungus ZPRa-R-1. Under symbiosis conditions, regularity changes of key enzyme genes affected by endophytic fungus ZPRa-R-1 were as follows:the relative expression activity of PAL attached to peak value, which was 4.9 times as that of control group when inoculated ten days. The relative expression of TyDC reached the maximum value, which was 2.8 times of that control after inoculating 12 days. The relative expression of UDPGT actually reach 17.1 times than that of control after inoculating 8 days. However, the relative expression of TAT was not affected by this fungus. The changes of four key enzyme genes are positively correlated with the changes of salidroside content in R. crenulata.
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To better understand the biosynthetic pathway of flavonoids in Blumea balsamifera, and to increase the biosynthesis of flavone and flavonol amount, we carried out this research. Basing on transcriptome information, B. balsamifera flavonoids metabolic pathway was analyzed in KEGG data base. The result demonstrated that two metabolic pathways of flavonoids were found in KEGG data base. They were flavonoid biosynthesis pathway (No.ko00941) that contained 32 genes and flavone and flavonol biosynthesis pathway (No.ko00944) that contained 12 genes. Metabolic pathway of flavonoids in B. balsamifera was similar to that in other plants. Chalcone synthase (CHS) and Chalconeisomerase were much likely to be key enzymes on metabolic pathway of flavonoids in B. balsamifera. HCT was much relevant to biosynthesis of favones.
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Cytosine arabinoside (Ara-C) is one of the key chemotherapy drugs comprising all stages combined protocols during long-term chemotherapy for children with acute leukemias,which demonstrated its efficacy and safety.Along with the progress of basic and clinical researches,in Ara-C clinical dose and treatment,prevention of adverse reactions,relationship between the drug metabolism and long-term clinical results,and new nucleoside drugs have achieved remarkable results.This paper on the above fields of research,progress and trends,briefly summarized as follows.