• Journal of Microbiology and Biotechnology
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• 제21권11호
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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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• 제25권5호
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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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• 제17권3호
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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.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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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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• 제32권1호
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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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• 제29권6호
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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.

• 미생물학회지
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• 제41권2호
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• pp.105-111
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• 2005

다양한 균주들을 대상으로 무작위로 신물질을 스크리닝하는 방법은 많은 노력과 시간이 소요되는 방법이며, 신물질을 발견하는 비율도 계속 낮아지고 있다. 따라서 기존 균주들을 대상으로 microarray 기술을 이용한 target-directed screening기술의 개발은, 학문적 뿐만 아니라 산업적으로도 중요한 의미를 가진다. 본 연구에서는, 이미 분리된 방선균각각의 유전체를 대상으로 microarray 분석을 통해, 새로운 생리활성 물질 생산균주 및 생합성 유전자를 확보할 수 있는 기법을 개발하기 위한 기초실험을 수행하였다. 즉, 기존에 알려진 생리활성물질 생합성 유전자들을 확보하여 DNA chip을 제조하였으며, 유전체 염기서열이 밝혀진 S. coelicolor 균주를 대상으로 그 효율성을 검증하였다. 전체적으로 유전자 상동성이 높을수록 반응감도도 높은 편이었으나, 이러한 상환관계가 일치하지 않는 유전자들도 있었다. 이와 같은 문제는, probe 유전자의 G+C 비율$(\%)$을 서로 비슷하게 구성하거나, 반응조건을 최적화 시킨다면 DNA chip의 효율성을 더욱 높일 수 있을 것으로 판단된다. DNA microarray를 통한 생리활성물질 발굴 연구는 세계적으로도 보고된 바 없는 새로운 접근방법으로서, 본 연구에서 시도하고 있는 방법은 발굴 target과 대상을 지정하고 시도되기 때물에, 효율면에서 무작위 스크리닝과는 비교되지 않을 정도로 높을것으로 예상된다. 또한 본 연구와 같은 접근방법을 최적화 시킨다면, 방선균뿐만 아니라 다른 미생물부터 생리활성물질 및 생합성유전자 스크리닝에도 효과적으로 응용할 수 있을 것이다.

• Journal of Plant Biotechnology
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• 제46권4호
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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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• 제34권4호
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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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• 제48권1호
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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.