• Natural Product Sciences
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• 제26권3호
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• pp.183-190
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• 2020

Genome mining has recently emerged as a powerful strategy to discover novel microbial secondary metabolites. However, more than 50% of biosynthetic gene clusters are not transcribed under standardized laboratory culture condition. Several methods have been applied to activate silent biosynthetic gene clusters in the microbes so far. Among the regulatory systems for production of secondary metabolites, global regulators, which affect transcription of genes through regulatory cascades, typically govern the production of small molecules. In this review, global regulators to affect production of microbial secondary metabolites were discussed.

• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.1909-1921
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• 2007

Significant progress has recently been made concerning the engineering of deoxysugar biosynthesis. The biosynthetic gene clusters of several deoxysugars from various polyketides and aminoglycosides-producing microorganisms have been cloned and studied. This review introduces the biosynthetic pathways of several deoxysugars and the generation of novel hybrid macrolide antibiotics via the coexpression of deoxysugar biosynthetic gene cassettes and the substrate-flexible glycosyltransferases in a host organism as well as the production of TDP-deoxysugar derivatives via one-pot enzymatic reactions with the identified enzymes. These recent developments in the engineering of deoxysugars biosynthesis may pave the way to create novel secondary metabolites with potential biological activities.

• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.906-911
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• 2003

The function of genes related to spectinomycin biosynthesis (spcD, speA, speB, spcS2) from Streptomyces spectabilis ATCC 27741, a spectinomycin producer, was analyzed. Each gene was subcloned from a spectinomycin biosynthetic gene cluster and overexpressed in E. coli BL21 (DE3) using pET vector. After incubating each purified protein with its possible substrates, the final products were analyzed using high-performance liquid chromatography (HPLC). From these results, spcD, speA, and speB have been identified to be dTDP-glucose synthase, myo-inositol monophosphatase, and myo-inositol dehydrogenase, respectively. In addition, the results suggest that the spcS2 gene product functions downstream of the speB gene product in the biosynthetic pathway of spectinomycin. Taken together, the present study elucidates the early steps of the biosynthetic pathway for 6-deoxyhexose (6-DOH) part (actinospectose) and aminocyclitol part (actinamine) of spectinomycin.

• Animal cells and systems
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• 제6권4호
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• pp.305-309
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• 2002

Actinorhodin antibiotics produced by Streptomyces lividans TK24 are blue pigments with a weak antibiotic activity, derived from one acetyl-CoA and 15 malonyl-CoA units via a typical ployketide pathway. In an attempt to clone polyketide biosynthetic genes of S. lividans TK24, hybridizing fragments in the genomic DNA of S. lividans TK24 were detected by use of acn and act III polyketide synthase gene probes. Since typical aromatic polyketide bio-synthetic gene clusters are roughly 22-34 Kb long, we constructed in E. coli XL-Blue MR using the Streptomyces-E. coli bifunctional shuttle cosmid vector (pojn46). Then, about 5,000 individual E. coii colonies were thor-oughly screened with acrl-ORFI and actIII probes. From these cosmid libra-ries, 12 positive clones were identified. Restriction analysis and southern hybridization showed two polyketide biosynthetic gene clusters in this organism. These cosmid clones can be transformed into Streptomyces parvulus 12434 for expression test that identify product of actinorhodin biosynthetic genes by heterologous expression. Thus, heterologous expres-sion of a derivative compound of a actinorhodin biosynthetic intermediate was obtained in pKE2430. Expression of these compounds by the trans-formants was detected by photodiode array HPLC analysis of crude extracts.

• 한국미생물·생명공학회지
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• 제32권3호
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• pp.282-285
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• 2004

The polyene antibiotics including nystatin, pimaricin, amphotericin and candicidin are a family of most promising antifungal polyketide compounds, typically produced by rare actinomycetes species. The biosynthetic gene clusters for these polyenes have been previously investigated, revealing the presence of highly homologous biosynthetic genes among polyene-producers such as polyketide synthase (PKS) and cytochrome P450 hydroxylase (CYP) genes. Based on amino acid sequence alignment among actinomycetes CYP genes, the highly-conserved regions specific for only polyene CYP genes were identified and chosen for degenerate PCR primers, followed by the PCR-screening with various actinomycetes genomic DNAs. Among tested several polyene non-producing actinomycetes strains, Pseudonorcardia autotrophica strain was selected based on the presence of PCR product with polyene-specific CYP gene primers, and then confirmed to contain a cryptic novel polyene hydroxylase gene in the chromosome. These results suggest that the polyene-specific hydroxylase gene PCR should be an efficient way of screening and isolating potentially-valuable cryptic polyene antibiotic biosynthetic genes from various microorganisms including rare actinomycetes.

• Journal of Microbiology
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• 제44권1호
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• pp.121-125
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• 2006

Mycothiol is a low molecular weight thiol compound produced by a number of actinomycetes, and has been suggested to serve both anti-oxidative and detoxifying roles. To investigate the metabolism and the role of mycothiol in Streptomyces coelicolor, the biosynthetic genes (mshA, B, C, and D) were predicted based on sequence homology with the mycobacterial genes and confirmed experimentally. Disruption of the mshA, C, and D genes by PCR targeting mutagenesis resulted in no synthesis of mycothiol, whereas the mshB mutation reduced its level to about $10\%$ of the wild type. The results indicate that the mshA, C, and D genes encode non-redundant biosynthetic enzymes, whereas the enzymatic activity of MshB (acetylase) is shared by at least one other gene product, most likely the mca gene product (amidase).

• Journal of Microbiology and Biotechnology
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• 제22권11호
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• pp.1478-1481
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• 2012

Geldanamycin (GM) and its analogs are important anticancer agents that inhibit heat shock protein (Hsp) 90, which is a major chaperone protein in cancer cells. Accordingly, based on interest in obtaining novel natural GM derivatives, the potential of Streptomyces hygroscopicus JCM4427, a GM producer, was explored for novel natural GM derivative(s), resulting in the discovery of new GM analogs as a biosynthetic shunt product and intermediates from its fermentation broth. In this study, the fermentation, isolation, structure determination, and biological activity of the compounds, two new tetracyclic thiazinogeldanamycin (1) and 19-hydroxy-4,5-dihydrogeldanamycin (3), together with the three known 4,5-dihydrothiazinogeldanamycin (2), reblastatin (4), and 17-demethoxy-reblastatin (5), are described.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.614-618
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• 2014

Resveratrol, which is a polyphenolic antioxidant, is dose-dependent when used to provide health benefits, to enhance stress resistance, and to extend lifespans. However, even though resveratrol has therapeutic benefits, its clinical therapeutic effect is limited owing to its low oral bioavailability. An Escherichia coli system was developed that contains an artificial biosynthetic pathway that produces resveratrol glucoside derivatives, such as resveratrol-3-Oglucoside (piceid) and resveratrol-4'-O-glucoside (resveratroloside), from simple carbon sources. This artificial biosynthetic pathway contains a glycosyltransferase addition (YjiC from Bacillus) with resveratrol biosynthetic genes. The produced glucoside compounds were verified through the presence of a product peak(s) and also through LC/MS analyses. The strategy used in this research demonstrates the first harnessing of E. coli for de novo synthesis of resveratrol glucoside derivatives from a simple sugar medium.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1999년도 춘계학술대회
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• pp.5-8
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• 1999

여성의 breast cancer의 1/3 의 경우가 hormone-dependent에 의한 것이다. 따라서 그 치료의 접근 방법으로써 estrogen receptor에 작용하거나, receptor-mediated gene trenscription을 저해하는 antiestrogen을 사용하는 것이 있다. Estrogen은 microsomal cytochrome P-450 enzyme complex system에 의해 androgen으로부터 생합성되는 hormone이며, estrogen product는 steroid product의 biosynthetic sequence의 마지막 단계에서 생산되고, aromatase는 이에 관여하는 enzyme으로써, aromatase를 선택적으로 저해하는 경우에 다른 steroid의 생산에 영향을 미치지 않고 estrogen 생산을 감소 시킬 수 있다. 이러한 관점에서, aromatase를 선택적으로 저해하는 것은 hormone-dependent breast cancer를 완화시킬 수 있는 가능성을 가진 cancer chernopreventive agents의 새로운 방법이라 할 수 있다.

• 식물조직배양학회지
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• 제27권4호
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• pp.269-282
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• 2000

Benzylisoquinoline alkaloids are a diverse group of natural products that include many pharmacologically active compounds produced in a limited number of plant families. Despite their complexity, intensive biochemical research has extended our knowledge of the chemistry and enzymology of many important benzylisoquinoline alkaloid pathways, such as those leading to the analgesic drugs morphine and codeine, and the antibiotics sanguinarine and berberine. The use of cultured plant cells as an experimental system has facilitated the identification and characterization of more than 30 benzylisoquinoline alkaloid biosynthetic enzymes, and the molecular cloning of the genes that encode at least 8 of these enzymes. The recent expansion of biochemical and molecular technologies has creat-ed unique opportunities to dissect the mechanisms involved in the regulation of benzylisoquinoline alkaloid biosynthesis in plants. Research has suggested that product accumulation is controlled by the developmental and inducible regulation of several benzylisoquinoline alkaloid biosynthetic genes, and by the subcellular compartmentation of biosynthetic enzymes and the intracellular localization and trafficking of pathway intermediates. In this paper, we review our current understanding of the biochemistry, cell biology, and molecular regulation of benzylisoquinoline alkaloid biosynthesis in plants. We also summarize our own research activities, especially those related to the establishment of protocols for the genetic transformation of benzylisoquinoline alkaloid-producing species, and the development of metabolic engineering strategies in these plants.