• 미생물학회지
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• 제28권4호
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• pp.351-363
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• 1990

A mutant was selected by NTG treatment of Mycobacterium sp. NRRL B-3805, which was capable of degrading plant sterol to androsta-4-ene-3, 17-dione and yields was higher than NRRL B-3805. Also this mutant produced androst-4-ene-3, 17-dione faster than NRRL B-3805. It described the mode of sitosteroidal degradation, and the interrelation between cell membrane and its attachment to substrate during the sterol degradation process by this mutant and it was compared with Mvcobacterium sp. NRRL B-3805.

• The Korean Journal of Physiology and Pharmacology
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• 제17권4호
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• pp.291-297
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• 2013

Notch1 has been reported to be highly expressed in triple-negative and other subtypes of breast cancer. Mutant p53 (R280K) is overexpressed in MDA-MB-231 triple-negative human breast cancer cells. The present study aimed to determine whether the mutant p53 can be a potent transcriptional activator of the Notch1 in MDA-MB-231 cells, and explore the role of this mutant p53-Notch1 axis in curcumin-induced apoptosis. We found that curcumin treatment resulted in an induction of apoptosis in MDA-MB-231 cells, together with downregulation of Notch1 and its downstream target, Hes1. This reduction in Notch1 expression was determined to be due to the decreased activity of endogenous mutant p53. We confirmed the suppressive effect of curcumin on Notch1 transcription by performing a Notch1 promoter-driven reporter assay and identified a putative p53-binding site in the Notch1 promoter by EMSA and chromatin immunoprecipitation analysis. Overexpression of mutant p53 increased Notch1 promoter activity, whereas knockdown of mutant p53 by small interfering RNA suppressed Notch1 expression, leading to the induction of cellular apoptosis. Moreover, curcumin-induced apoptosis was further enhanced by the knockdown of Notch1 or mutant p53, but it was decreased by the overexpression of active Notch1. Taken together, our results demonstrate, for the first time, that Notch1 is a transcriptional target of mutant p53 in breast cancer cells and suggest that the targeting of mutant p53 and/or Notch1 may be combined with a chemotherapeutic strategy to improve the response of breast cancer cells to curcumin.

• 식물조직배양학회지
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• 제22권6호
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• pp.345-350
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• 1995

완두 돌연변이체 ageotropum 뿌리의 굴중성 결여에 대하여 조사하였다. 정상 완두의 뿌리에서 에틸렌은 굴중성 반응을 억제하였다. 돌연변이체에서는 에틸렌이나 에틸렌 생합성 억제제 또는 작용 억제제 모두 뿌리의 굴중성 반응 결여를 회복시키지 못하였다. 옥신을 비대칭으로 처리한 뿌리에서 굴성반응이 일어나는 것으로 보아 옥신의 작용은 정상적으로 일어나는 것으로 판단되었다. 내생적 또는 옥신유도에 의한 에틸렌 생성은 정상 완두나 돌연변이체에서 크게 차이가 없었다. 그러나 정상 완두에서와는 달리 돌연변이체의 뿌리에서는 굴중성 반응의 작동체계인 옥신작용의 결함이 아니고 중력의 인식 또는 전달과정에 결함이 있다는 결론을 얻었다.

• 생명과학회지
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• 제8권1호
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• pp.8-13
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• 1998

옥수수의 미토콘드리아 변이체(NGS2)는 전자전달계 내의 NADH dehydrogenase를 구성하고 있는 subunit 4와 7 유전자의 재조합에 의해서 생성된 변이체이다. 이들의 변이체들은 식물의 성장과 발육에 절대적인 영양을 미치며, 또한 기내에서의 callus line들의 생성과 발달에도 상당한 영향을 미친다. 이들의 미토콘드리아 mutant 들은 3개의 primer를 사용하는 PCR 방법에 의해서 쉽게 선별이 가능하며, 세포 내의 키토콘드리아 변이 정도를 간접적으로 추측케 하며, 체시포 분열시 세포질 내의 기관들이 random으로 분리되는 현상을 간법적으로 알 수 있다. NGS2 mutant들에서 유기된callus line들은 식물체 재문화에도 영향을 미쳐 murant 미토콘드리아가 많은 call line들에슨 실질적인 부정 줄기의 유기를 방해하는 것으로 사료된다. 결론적으로 NADH-dehydrogenase는 식물체가 재분화 또는 성장하는데 있엇 필요한 요소라고 생각된다.

• 생명과학회지
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• 제17권1호
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• pp.39-44
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• 2007

분열형 효모에서 Rqh1은 Top3과 함께 vegetative growth에 필수적이다. $rqh^-$ 돌연변이는 DNA damaging agent에 민감성을 보이는데 이때, 부적절한 유전자 발현, 세포 신장, 염색체의 불안전성, 비정상적인 다중격막, 발아의 결핍을 포함한 넓은 범위의 표현형을 보인다. rqh1-overexpression cell 역시 rqh1 deletion mutant에서 보이는 DNA damaging agent 민감성을 관찰할 수 있다. 논문은 nmtl promoter를 가지는 PREP vector에 Rqhl이 과발현 할 때 나타나는 DNA damaging agent 민감성를 보상하는 유전자를 찾아 $rqh1^+$의 기능을 알아보는 것이다. 여기서 보상능이 보이는 rqh156, rqh172 두 개의 돌연변이를 골라냈다. rqhl deletion mutant의 DNA damaging agent 민감성은 rqh156, rqh172의 발현에 의해 보상 되어지는 것을 확인하였다.

• Journal of Ginseng Research
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• 제46권4호
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• pp.505-514
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• 2022

Background: The roots of Panax ginseng contain two types of tetracyclic triterpenoid saponins, namely, protopanaxadiol (PPD)-type saponins and protopanaxatiol (PPT)-type saponins. In P. ginseng, the protopanaxadiol 6-hydroxylase (PPT synthase) enzyme catalyses protopanaxatriol (PPT) production from protopanaxadiol (PPD). In this study, we constructed homozygous mutant lines of ginseng by CRISPR/Cas9-mediated mutagenesis of the PPT synthase gene and obtained the mutant ginseng root lines having complete depletion of the PPT-type ginsenosides. Methods: Two sgRNAs (single guide RNAs) were designed for target mutations in the exon sequences of the two PPT synthase genes (both PPTa and PPTg sequences) with the CRISPR/Cas9 system. Transgenic ginseng roots were generated through Agrobacterium-mediated transformation. The mutant lines were screened by ginsenoside analysis and DNA sequencing. Result: Ginsenoside analysis revealed the complete depletion of PPT-type ginsenosides in three putative mutant lines (Cr4, Cr7, and Cr14). The reduction of PPT-type ginsenosides in mutant lines led to increased accumulation of PPD-type ginsenosides. The gene editing in the selected mutant lines was confirmed by targeted deep sequencing. Conclusion: We have established the genome editing protocol by CRISPR/Cas9 system in P. ginseng and demonstrated the mutated roots producing only PPD-type ginsenosides by depleting PPT-type ginsenosides. Because the pharmacological activity of PPD-group ginsenosides is significantly different from that of PPT-group ginsenosides, the new type of ginseng mutant producing only PPD-group ginsenosides may have new pharmacological characteristics compared to wild-type ginseng. This is the first report to generate target-induced mutations for the modification of saponin biosynthesis in Panax species using CRISPR-Cas9 system.

• Journal of Microbiology and Biotechnology
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• 제34권5호
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• pp.1178-1187
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• 2024

Cordyceps militaris is a significant edible fungus that produces a variety of bioactive compounds. We have previously established a uridine/uracil auxotrophic mutant and a corresponding Agrobacterium tumefaciens-mediated transformation (ATMT) system for genetic characterization in C. militaris using pyrG as a screening marker. In this study, we constructed an ATMT system based on a dual pyrG and hisB auxotrophic mutant of C. militaris. Using the uridine/uracil auxotrophic mutant as the background and pyrG as a selection marker, the hisB gene encoding imidazole glycerophosphate dehydratase, required for histidine biosynthesis, was knocked out by homologous recombination to construct a histidine auxotrophic C. militaris mutant. Then, pyrG in the histidine auxotrophic mutant was deleted to construct a ΔpyrG ΔhisB dual auxotrophic mutant. Further, we established an ATMT transformation system based on the dual auxotrophic C. militaris by using GFP and DsRed as reporter genes. Finally, to demonstrate the application of this dual transformation system for studies of gene function, knock out and complementation of the photoreceptor gene CmWC-1 in the dual auxotrophic C. militaris were performed. The newly constructed ATMT system with histidine and uridine/uracil auxotrophic markers provides a promising tool for genetic modifications in the medicinal fungus C. militaris.

• 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.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.727-730
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• 2001

Xanthomonas oryzae #5로부터 클로닝 된 CFTase 의 functional domain의 분석을 위해 CFTase의 recombinant deletion mutant를 구성하고, recombinant protein을 분리, 정제하였다. 분리, 정제한 recombinant protein의 활성을 측정한 결과 C-terminal이 deletion 된 mutant는 cyclization 반응이 소실 되었다. 이와 같은 결과로부터 CFTase의 C-terminal 은 cyclization 반응의 중요한 functional domain 이다.

• Journal of Microbiology and Biotechnology
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• 제16권5호
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• pp.771-777
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• 2006

A novel gene (agiA) required for adventurous gliding motility in Myxococcus xanthus has been identified. Null mutations in this gene caused defects in the gliding movement of isolated cells, suggesting that it belongs to one of the A-motility genes. The isolated agiA mutant cells neither glided nor produced slime trails on agar surface. However, agiA was different from other known A-motility genes in that the agiA mutant created in the $S^-$ mutant background glided in the swarm of cells, since other known A-motility mutants created in the $S^-$ mutant background do not move in the swarm of cells. The agiA mutant was also defective in fruiting body development. Sequence analysis predicted that agiA encodes a 787-amino-acid protein with eight tripeptide repeat motifs.