• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1143-1146
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• 2011

Metabolic engineering of plant-specific phenylpropanoid biosynthesis has attracted an increasing amount of attention recently, owing to the vast potential of flavonoids as nutraceuticals and pharmaceuticals. Recently, we have developed a recombinant Streptomyces venezuelae as a heterologous host for the production of flavonoids. In this study, we successfully improved flavonoid production by expressing two sets of genes predicted to be involved in malonate assimilation. The introduction of matB and matC encoding for malonyl-CoA synthetase and the putative dicarboxylate carrier protein, respectively, from Streptomyces coelicolor into the recombinant S. venezuelae strains expressing flavanone and flavone biosynthetic genes resulted in enhanced production of both flavonoids.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.658-661
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• 2015

Genes encoding enzymes with sequence similarity to hopanoids biosynthetic enzymes of other organisms were cloned from the hopanoid (hop) gene cluster of Streptomyces peucetius ATCC 27952 and transformed into Streptomyces venezuelae YJ028. The cloned fragments contained four genes, all transcribed in one direction. These genes encode polypeptides that resemble polyprenyl diphosphate synthase (hopD), squalene-phytoene synthases (hopAB), and squalene-hopene cyclase (hopE). These enzymes are sufficient for the formation of the pentacyclic triterpenoid lipid, hopene. The formation of hopene was verified by gas chromatography/mass spectrometry.

• Journal of Microbiology and Biotechnology
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• v.17 no.3
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• pp.534-538
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• 2007

Avermectin and its analogs are major commercial antiparasitic agents in the fields of animal health, agriculture, and human infections. To increase our understanding about the genetic mechanism underlying avermectin overproduction, comparative transcriptomes were analyzed between the low producer S. avermitilis ATCC31267 and the high producer S. avermitilis ATCC31780 via a S. avermitilis whole genome chip. The comparative transcriptome analysis revealed that fifty S. avermitilis genes were expressed at least two-fold higher in S. avermitilis ATCC31780. In particular, all the avermectin biosynthetic genes, including polyketide synthase (PKS) genes and an avermectin pathway-specific regulatory gene, were less expressed in the low producer S. avermitilis ATCC31267. The present results imply that avermectin overproduction in S. avermitilis ATCC31780 could be attributed to the previously unidentified fifty genes reported here and increased transcription levels of avermectin PKS genes.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.352-352
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• 2006

Corynebacterium glutamicum, which is well known as an amino acid fermentation bacterium, has been used as a producer of poly(3-hydroxybutyrate) [P(3HB)]. P(3HB) was synthesized in recombinant C. glutamicum harboring the expression plasmid vector with a strong promoter for cell surface protein gene derived from C. glutamicum and P(3HB) biosynthetic gene operon derived from Ralstonia eutropha. The expression of P(3HB) synthase gene was detected by enzyme activity assay. Intracellular P(3HB) was microscopically observed as inclusion granules and its content was calculated to be 22.5 % (w/w) with molecular weight of $2.1{\times}10^{5}$ and polydispersity of 1.63.

• BMB Reports
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• v.32 no.1
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• pp.72-75
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• 1999

In an effort to understand the function of the eryBVII gene in the erythromycin biosynthetic gene cluster, we overexpressed the eryBVII gene in E. coli and TDP-6-deoxy-L-threo-D-glycero-4-hexulose was used as a substrate of the overexpressed EryBVII enzyme. The enzymatic reaction product was chemically modified by reduction and peracetylation. Structural analysis of the derivatized enzymatic products by GC-Mass Spectrophotometry indicated that TDP-6-deoxy-L-threo-D-glycero-4-hexulose could be converted into its epimer by EryBVII enzyme. Based on this result, TDP-6-deoxy-L-threo-D-glycero-4-hexulose was indeed the substrate of EryBVII enzyme and the function of the eryBVII gene was confirmed.

• Journal of Microbiology and Biotechnology
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• v.29 no.6
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• pp.845-855
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• 2019

Synthetic biology builds programmed biological systems for a wide range of purposes such as improving human health, remedying the environment, and boosting the production of valuable chemical substances. In recent years, the rapid development of synthetic biology has enabled synthetic bacterium-based diagnoses and therapeutics superior to traditional methodologies by engaging bacterial sensing of and response to environmental signals inherent in these complex biological systems. Biosynthetic systems have opened a new avenue of disease diagnosis and treatment. In this review, we introduce designed synthetic bacterial systems acting as living therapeutics in the diagnosis and treatment of several diseases. We also discuss the safety and robustness of genetically modified synthetic bacteria inside the human body.

• Korean Journal of Microbiology
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• v.41 no.2
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• pp.105-111
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• 2005

Streptomyces produces many kinds of secondary-metabolites including antibiotics. Screening of a new compound and elucidation of a biosynthetic pathway for the secondary metabolites are very important fields of biology, however, there is a main problem that most of the identified compounds are already researched compounds. To solve these problems, a microarray system that is based on the data related to the biosynthetic genes for secondary-metabolites was designed. For the main contents of DNA microarray, the important genes for the bio-synthesis of aminoglycosides, polyenes group, enediyne group, alpha-glucosidase inhibitors, glycopeptide group, and orthosomycin group were chosen. A DNA microarray with 69 genes that were involved in the bio-synthesis for the antibiotics mentioned above was prepared. The usability of the DNA microarray was confirmed with the chromosomal DNA and total RNA extracted from S. coelicolor whose genomic sequence had already been reported.

• Journal of Plant Biotechnology
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• v.46 no.4
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• pp.247-254
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• 2019

Flavonoids are widely distributed secondary metabolites in plants that have a variety biological functions, as well as beneficial biological and pharmacological activities. In barley (Hordeum vulgare L.), for example, high levels of saponarin accumulate during primary leaf development. However, the effect of saponarin biosynthetic pathway genes on the accumulation of saponarin in barley is poorly understood. Accordingly, the aim of the present study was to examine the saponarin contents and expression levels of saponarin biosynthetic pathway genes [chalcone synthase (CHS), chalcone isomerase (CHI), and UDP-Glc:isovitexin 7-O-glucosyltransferase (OGT)] during early seedling developmental and under several abiotic stress conditions. Interestingly, the upregulation of HvCHS, HvCHI, and HvOGT during early development was associated with saponarin accumulation during later stages. In addition, exposure to abiotic stress conditions (e.g., light/dark transition, drought, and low or high temperature) significantly affected the expression of HvCHS and HvCHI but failed to affect either HvOGT expression or saponarin accumulation. These findings suggested that the expression of HvOGT, which encodes an enzyme that catalyzes the final step of saponarin biosynthesis, is required for saponarin accumulation. Taken together, the results of the present study provide a basis for metabolic engineering in barley plants, especially in regards to enhancing the contents of useful secondary metabolites, such as saponarin.

• Journal of Microbiology
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• v.34 no.4
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• pp.355-362
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• 1996

Complementation cloning of the argC, E, B, D, F, and G genes in Corynebacterium glutamicum was done by transforming the genomic DNA library into the corresponding arginine auxotrophs fo Escherichia coli. Recombinant plasmids containing 6.7 kb and 4.8kb fragments complementing the E. coli argB mutant were also able to complement the E. coli argC, E, A, D, and F mutants, indicating the clustered organization of the arginine biosynthetic genes within the cloned DNA fragments. The insert DNA fragments in the recombinant plasmids, named pRB1 AND pRB2, were physically mapped with several restriction enzymes. By further subcloning the entire DNA fragment containing the functions and by complementation analysis, we located the arg genes in the order of ACEBDF on the restriction map. We also determined the DNA nucleotide sequence of the fragment and report here the sequence of the argB gene. When compared to that with the mutant strain, higher enzyme activity of N-acetylglutamate kinase was detected in the extract of the mutant carrying the plasmid containing the putative argB gene, indicating that the plasmid contains a functional argB gene. Deduced amino acid sequence of the argB gene shows 45%, 38%, and 25% identity to that from Bacillus strearothermophilus, Bacillus substilus, and E. coli respectively. Our long term goal is genetically engineering C. glutamicum which produces more arginine than a wild type strain does.

• Journal of Plant Biotechnology
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• v.48 no.1
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• pp.12-17
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• 2021

Saponarin found in young barley sprouts has a variety of beneficial biological and pharmacological properties, including antioxidant, hypoglycemic, antimicrobial, and hepatoprotective activities. Our previous work demonstrated that saponarin content was correlated with the expression levels of three biosynthetic pathway genes [chalcone synthase (HvCHS1), chalcone isomerase (HvCHI), and UDP-Glc:isovitexin 7-O-glucosyltransferase (HvOGT1)] in young barley seedlings under various abiotic stress conditions. In this study, we investigated the saponarin content and expression levels of three saponarin biosynthetic pathway genes in hulled and hulless domestic barley cultivars. In the early developmental stages, some hulled barley cultivars (Kunalbori1 and Heukdahyang) had much higher saponarin contents than did the hulless barley cultivars. An RNA expression analysis showed that in most barley cultivars, decreased saponarin content correlated with reduced expression of HvCHS1 and HvCHI, but not HvOGT1. Heat map analysis revealed both specific increases in HvCHS1 expression in certain hulled and hulless barley cultivars, as well as general changes that occurred during the different developmental stages of each barley cultivar. In summary, our results provide a molecular genetic basis for the metabolic engineering of barley plants to enhance their saponarin content.