• Journal of Microbiology and Biotechnology
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• v.5 no.2
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• pp.74-79
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• 1995

Sequence analysis of a DNA region encompassing the site of hybridization to actl, the gene for type II minimal polyketide synthase (PKS) for actinorhodin biosynthesis, from Streptomyces ablus revealed three more complete open reading frames additional to the already found two genes, plausibly encoding ${\beta}-ketoacyl$ synthase/acyl transferase (KS/AT) and chain length determining factor (ClF). The open reading frames (ORFs) were named salA, salD, and salE, from the upstream. In the homology analysis of the deduced amino acid sequences, SalA resembles the Streptomyces glaucescens Tcml, decaketide cyclase, SalD resembles acyl carrier protein in type II PKS, and SalE resembles the Actlll ketoreductase, The whole 4.4 kb of DNA sequence obeys the same conservation pattern as other type II PKSs. Therefore, we suggest that the 4.4 kb DNA from Streptomyces albus encompasses genes encoding enzymes for polyketide biogenesis in the organism and its organization is type II. The exsitence of SaIA, an analogue of the aromatic cyclase, revealed a relatedness of the 4.4 kb DNA with the aromatic PKS.

• Proceedings of the Zoological Society Korea Conference
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• 1994.10a
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• pp.64-64
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• 1994

No Abstract, See Full Text

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.119-119
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• 2005

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.764-770
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• 2006

Dihydrochalcomycin (GERI-155), produced by Streptomyces sp. KCTC-0041BP isolated from Korean soil, is a 16-membered macrolide antibiotic consisting of two deoxysugar moieties at C-5 and C-20 positions of a branched lactone ring. The cloning and sequencing of a gene cluster for dihydrochalcomycin biosynthesis revealed a 63-kb nucleotide region containing 25 open reading frames (ORFs). The products of all of these 25 ORFs playa role in dihydrochalcomycin biosynthesis and self-resistance against the compounds synthesized. At the core of this cluster lies a 39.6-kb polyketide synthase (PKS) region encoding eight modules in five giant multifunctional protein-coding genes (gerSI-SV). The genes responsible for the biosynthesis of deoxysugar moieties, D-chalcose and D-mycinose, and their modification and attachment were found on either side of this PKS region. The involvement of this gene cluster in dihydrochalcomycin biosynthesis was confirmed by disruption of the dehydratase (DH) domain in module 3 of the PKS gene and by metabolite analysis.

• Proceedings of the PSK Conference
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• 2003.10a
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• pp.75-78
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• 2003

Polyketides are a class of structurally diverse natural products which possess a wide range of biological activities. These compounds are used throughout medicine and agriculture as antimicrobials, immunosuppressants, antiparasitics, and anticancer agents. While structurally diverse, polyketides are assembled by a common mechanism of decarboxylative condensations of simple malonate derivatives by polyketide synthases (PKSs) in a manner very similar to fatty acid biosynthesis (Fig 1). (omitted)

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.420-422
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• 2005

TMC (Tautomycetin) is a liner polyketide immunosuppressive antifungal compound produced by Streptomyces spp. Inhibition of T cell proliferation with TMC was observed highly efficient at 100-fold lower than those needed to achieve maximal inhibition with cyclosporin A. To elucidate the biosynthetic pathway of TMC, a genomic DNA library was constructed using a E. coil-Streptomyces shuttle cosmid vector, pOJ446. The DNA libraries were screened by colony blot hybridization using several polyketide ${\beta}-ketosynthase$ (KS) probes amplified from TMC-producing Streptomyces genomic DNA using polymerase chain reaction (PCR), of which the degenerate primers were designed based on the highly conserved sequences present in KS domains of various type I polyketide synthase genes in Streptomyces species. This library construction and screening approach led to the isolation of several positive cosmid clones representing type I polyketide biosynthetic gene clusters. In addition, a Streptomyces regulatory gene called afsR2 (a global regulatory gene stimulating antibiotic production in both S. coelicolor and S. lividans) was successfully integrated into the TMC-producing Streptomyces chromosome via E. coil-Streptomyces heterologous conjugation mehtod. The more detailed results of production improvement and genetic characterization of TMC-producing Streptomyces spp. will be discussed.

• Journal of Microbiology
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• v.43 no.3
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• pp.277-284
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• 2005

The avermectins are composed of eight compounds, which exhibit structural differences at three positions. A family of four closely-related major components, A1a, A2a, B1a and B2a, has been identified. Of these components, B1a exhibits the most potent antihelminthic activity. The coexistence of the '1' components and '2' components has been accounted for by the defective dehydratase of aveAI module 2, which appears to be responsible for C22-23 dehydration. Therefore, we have attempted to replace the dehydratase of aveAI module 2 with the functional dehydratase from the erythromycin eryAII module 4, via homologous recombination. Erythromycin polyketide synthetase should contain the sole dehydratase domain, thus generating a saturated chain at the C6-7 of erythromycin. We constructed replacement plasmids with PCR products, by using primers which had been derived from the sequences of avermectin aveAI and the erythromycin eryAII biosynthetic gene cluster. If the original dehydratase of Streptomyces avermitilis were exchanged with the corresponding erythromycin gene located on the replacement plasmid, it would be expected to result in the formation of precursors which contain alkene at C22-23, formed by the dehydratase of erythromycin module 4, and further processed by avermectin polyketide synthase. Consequently, the resulting recombinant strain JW3105, which harbors the dehydratase gene derived from erythromycin, was shown to produce only C22,23-unsaturated avermectin compounds. Our research indicates that the desired compound may be produced via polyketide gene replacement.

• Animal cells and systems
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• v.6 no.4
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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.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.596-596
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• 2003

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.662-662
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• 2005