• Journal of Microbiology and Biotechnology
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• 제7권5호
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• pp.363-366
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• 1997

A doxorubicin-nonproducing mutant, Nu23 was selected from the mutagenesis of Streptomyces peucetius ATCC27952. Chemical and molecular biological analysis suggested that the mutant was blocked at the step between polyketide synthase and aklaviketon reductase in the biosynthesis of doxorubicin. Furthermore, the bioconversion experiment with the mutant revealed that 13-dihydrodaunorubicin is likely to be a biosynthetic intermediate.

• 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.

• Journal of Microbiology and Biotechnology
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• 제20권11호
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• pp.1484-1490
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• 2010

In the Streptomyces hygroscopicus JCM4427 geldanamycin biosynthetic gene cluster, five putative regulatory genes were identified by protein homology searching. Among those genes, gel14, gel17, and gel19 are located downstream of polyketide synthase genes. Gel14 and Gel17 are members of the LAL family of transcriptional regulators, including an ATP/GTP-binding domain at the N-terminus and a DNA-binding helix-turn-helix domain at the C-terminus. Gel19 is a member of the TetR family of transcriptional regulators, which generally act to repress transcription. To verify the biological significance of the putative regulators in geldanamycin production, they were individually characterized by gene disruption, genetic complementation, and transcriptional analyses. All three genes were confirmed as positive regulators of geldanamycin production. Specifically, Gel17 and Gel19 are required for gel14 as well as gelA gene expression.

• Molecules and Cells
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• 제26권3호
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• pp.278-284
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• 2008

An open reading frame, designated GerGTII and located downstream of the polyketide synthase genes, has been identified as a chalcosyltransferase by sequence analysis in the dihydrochalcomycin biosynthetic gene cluster of Streptomyces sp. KCTC 0041BP. The deduced product of gerGTII is similar to several glycosyltransferases, authentic and putative, and it displays a consensus sequence motif that appears to be characteristic of a sub-group of these enzymes. Specific disruption of gerGTII within the S. sp. KCTC 0041BP genome by insertional in-frame deletion method, resulted complete abolishment of dihydrochalcomycin and got the 20-O-mycinosyl-dihydrochalconolide as intermediate product in dihydrochalcomycin biosynthesis which was confirmed by electron spray ionization-mass spectrometry and liquid chromatography-mass spectrometry. Dihydrochalcomycin also was recovered after complementation of gerGTII.

• 한국미생물·생명공학회지
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• 제51권1호
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• pp.128-131
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• 2023

Here we report the draft genome sequence of Weissella koreensis strain HJ and genomic analysis of its key features. The genome consists of 1,427,571 bp with a GC content of 35.5%, and comprises 1,376 coding genes. In silico analysis revealed the absence of pathogenic factors within the genome. The genome harbors several genes that play an important role in the survival of the gastrointestinal tract. In addition, a type III polyketide synthase cluster was identified. Pangenome analysis identified 68 unique genes in W. koreensis strain HJ. The genome information of this strain provides the basis for understanding its probiotic properties.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.510-515
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• 2006

The putative EPA synthesis gene cluster was mined from the entire genome sequence of Shewanella oneidensis MR-1. The gene cluster encodes a PKS-like pathway that consists of six open reading frames (ORFs): ORFSO1602 (multi-domain beta-ketoacyl synthase, KS-MAT-4ACPs-KR), ORFSO1600 (acyl transferase, AT), ORFSO1599 (multi-domain beta-ketoacyl synthase, KS-CLF-DH-DH), ORFSO1597 (enoyl reductase, ER), ORFSO1604 (phosphopentetheine transferase, PPT), and ORFSO1603 (transcriptional regulator). In order to prove involvement of the PKS-like machinery in EPA synthesis, a 20.195-kb DNA fragment containing the genes was amplified from S. oneidensis MR-1 by the long-PCR method. Its identity was confirmed by the methods of restriction enzyme site mapping and nested PCR of internal genes orfSO1597 and orfSO1604. The DNA fragment was cloned into Escherichia coli using cosmid vector SuperCos1 to form pCosEPA. Synthesis of EPA was observed in four E. coli clones harboring pCosEPA, of which the maximum yield was 0.689% of the total fatty acids in a clone designated 9704-23. The production yield of EPA in the E. coli clone was affected by cultivation temperature, showing maximum yield at $20^{\circ}C$ and no production at $30^{\circ}C$ or higher. In addition, production yield was inversely proportional to glucose concentration of the cultivation medium. From the above results, it was concluded that the PKS-like modules catalyze the synthesis of EPA. The synthetic process appears to be subject to regulatory mechanisms triggered by various environmental factors. This most likely occurs via the control of gene expression, protein stability, or enzyme activity.

• Journal of Microbiology and Biotechnology
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• 제21권4호
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• pp.359-365
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• 2011

Cyanobacterial strains of the genus Spirulina have recently been identified as an excellent source of sulfolipids, some of which possess anti-HIV properties. Thus, to investigate the distribution of sufolipid biosynthesis pathways in Spirulina, a genetic screening/phylogentic study was performed. Five different strains of Spirulina [Spirulina (Jiangmen), Spirulina sp., S. platensis, S. maxima, and Spirulina seawater] sourced from different locations were initially classified via 16S rDNA sequencing, and then screened for the presence of the sulfolipid biosynthesis genes sqdB and sqdX via a PCR. To assess the suitability of these strains for human consumption and safe therapeutic use, the strains were also screened for the presence of genes encoding nonribosomal peptide synthases (NRPSs) and polyketide synthases (PKSs), which are often associated with toxin pathways in cyanobacteria. The results of the 16S rDNA analysis and phylogenetic study indicated that Spirulina sp. is closely related to Halospirulina, whereas the other four Spirulina strains are closely related to Arthrospira. Homologs of sqdB and sqdX were identified in Spirulina (Jiangmen), Spirulina sp., S. platensis, and the Spirulina seawater. None of the Spirulina strains screened in this study tested positive for NRPS or PKS genes, suggesting that these strains do not produce NRP or PK toxins.

• 식물병연구
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• 제18권4호
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• pp.310-316
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• 2012

Gibberellea fujikuroi (Gf) 종복합체는 최소 15개의 종으로 구성되어 있으며, 대부분 식물에 병을 일으킬 뿐 아니라 푸모니신과 같은 곰팡이독소를 생성한다. 본 연구에서는 우리나라 벼와 옥수수로부터 분리한 Gf 종복합체 소속 야생형 균주의 푸모니신 생성능을 검정하였다. 이들 분석대상 균주는 모두 푸모니신 생합성에 필수적인 polyketide synthase 유전자 FUM1을 가지고 있는 것으로 확인되었다. 총 88주의 Gf 종복합체 소속 균주(55 F. fujikuroi, 10 F. verticillioides, 20 F. proliferatum, 2 F. subglutinans, 1 F. concentricum)와 Gf 종복합체의 근연종인 4주의 F. commune를 쌀 배지에 배양한 후 각 균주의 푸모니신 생성 농도를 HPLC 방법으로 측정하였다. 대부분의 F. verticillioides과 F. proliferatum 균주는 기주 식물에 관계없이 푸모니신 $B_1$($0.5-2,686.4{\mu}g/g$)과 $B_2$($0.7-1,497.6{\mu}g/g$)를 다양한 범위 내에서 생성하였다. 반면 모든 F. fujikuroi을 비롯한 다른 Fusarium spp.의 균주로부터는 푸모니신이 검출되지 않았거나 $10{\mu}g/g$ 이하 수준의 미량만 검출되었다. 흥미롭게도 F. proliferatum과 F. fujikuroi의 경우, 옥수수 유래 균주 집단에서 벼 유래 균주 집단에 비해 상대적으로 고농도 푸모니신 생성 균주의 비율이 높았다. 한편, FUM1 유전자를 함유하고 있는 F. commune의 푸모니신 생성능은 본 연구를 통해 처음 보고된다.

• 농약과학회지
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• 제18권4호
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• pp.396-403
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• 2014

인삼은 한국을 포함한 여러 국가에서 경제적으로 중요한 약용작물이다. 인삼에서 흔히 발생하는 뿌리썩음 병균을 친환경적으로 방제하기 위해서 병원균에 대해서 항균성이 있는 미생물을 탐색하였다. 토양에서 분리한 방선균 BK185균주는 인삼에 뿌리썩음병을 일으키는 병원균들(Cylindrocarpon, Fusarium, Rhizoctonia, Sclerotinia)에 대해서 높은 항균 활성을 보였다. 선발 균주 BK185의 동정을 위해서 16S rRNA 유전자 염기서열을 분석한 결과 Streptomyces 속에 해당하는 것으로 분석되었다. 특히, S. sporoclivatus 및 S. geldanamycininus와 99.6% 이상으로 매우 높은 유사도를 보였다. 선발 균주가 생산하는 2차 대사물질을 예측하기 위해서, 생산에 관여하는 생합성 유전자인PKS (Type-I polyketide synthase)와 NRPS (Non-ribosomal polypeptide synthetase) 유전자를 PCR반응을 통해 검출하였다. 검출된 유전자는 클로닝을 통해 염기서열을 결정하였다. 또한 최적 배양조건하에서 생산된 대사물질을 LC/MS로 분석하였고, geldanamycin 계열의 항생물질이 생산됨을 확인하였다.

• Journal of Applied Biological Chemistry
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• 제51권6호
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• pp.253-261
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• 2008

Isoflavone daidzein is a phytoestrogen widely distributed in Leguminosae and is especially rich in the soybean. The C6-C3 (rings B and C) unit of isoflavones is derived from the phenylpropanoid pathway and the remaining C6 (ring A) unit is from the polyketide pathway. This unique carbon skeleton is the result of isomerization of the flavone catalyzed by the isoflavone synthase, a cytochrome P450 enzyme. The isoflavones daidzein and genistein are present in the plant mostly in the glucosylated forms. However, in the human intestine, the glycosidic linkage is broken, and the free form is uptaked into blood stream. The free form is further metabolized into various reduction products to end up at the equol, which is known to have the most potent estrogenic effect among the metabolites. Several human intestinal bacteria that can convert daidzein into equol have been described, and the study into the chemistry and biochemistry of the daizein reduction would be rewarding to the improvement of the human health.