• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.39-46
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• 1994

Pseudomonas fluorescens Biovar III strains S-2 antagonistic to Rhizoctonia solani was subjected to Tn5 mutagenesis by the transposon vector pGS9. Ampicillin and kanamycin resistant (Ampr, Kmr) transconjugants were recovered at a frequency of 1.3$\times$10-7 per initial recipient cell, when recipient cells were washed twice in TE buffer before conjugation. Of the ca. 3000 transconjugants, a frequency of noninhibitory (Inh-), nonfluorescent (Flu-) and auxotorphic (Pro-) mutants were 0.27%, 0.47% and 0.40%, respectively. In these mutants, all Inh- mutants showed the same colony morphology as wild type, whereas all Flu- and Pro- mutants inhibited the growth of R. solani. These mutants were also susceptible to chloramphenicol, indicating only the Tn5 element, except for parts of pGS9, was integrated into the recipient genome. In a Southern blot analysis, the Tn5 element inserted into one site on the chromosome for each of the chosen mutants. However, Tn5 insertion sites of Inh-, and Pro- mutants were differed in each other. These indicate that the genes essential for R. solani inhibition, fluorescent production and auxotrophic are chromosomally located, but not linked to each other.

• Proceedings of the Botanical Society of Korea Conference
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• 2000.04a
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• pp.24-24
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• 2000

• Proceedings of the Botanical Society of Korea Conference
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• 1987.07a
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• pp.323-347
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• 1987

The R locus of maize in one of several genes that regulate the anthocyanin pigments throughout the body of the plant and seed. The R gene product may regulate pigment deposition by controlling the expression of the flavonoid biosynthetic gene pathway in a tissue-specific manner. To understand the basis for tissue specific regulation and allelic variation at R, the molecular study has been done by cloning a portion of the R complex by transposon tagging with Ac. R specific probe were cloned from the R-nj mutant induced by Ac insertion mutagenesis. From southern analysis of R-r complex using the R-nj probe, the structure of R-r was proposed that R-r containes the three elements, (P)(Q)(S). These elements may organize as the inversion triplication model which (S) sequence was inverted in relation to (P) and (Q). The R-sc derivated from R-mb or R-nj was cloned with R-nj probe, and molecular genetical data showed that R-sc containes tissue specific and tissue nonspecific area, and the sequencing of R-sc are progressed now.

• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1337-1345
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• 2005

Vibrio vulnificus is the causative agent of foodborne diseases such as gastroenteritis and life-threatening septicemia. Microbial pathogenicity is a complex phenomenon in which expression of numerous virulence factors is frequently controlled by a common regulatory system. In the present study, a mutant exhibiting decreased cytotoxic activity toward intestinal epithelial cells was screened from a library of V. vulnificus mutants constructed by a random transposon mutagenesis. By a transposon-tagging method, an open reading frame, fexA, a homologue of Escherichia coli areA, was identified and cloned. The nucleotide and deduced amino acid sequences of the fexA were analyzed, and the amino acid sequence of FexA from V. vulnificus was $84\%\;to\;97\%$ similar to those of AreA, an aerobic respiration control global regulator, from other Enterobacteriaceae. Functions of the FexA were assessed by the construction of an isogenic mutant, whose fexA gene was inactivated by allelic exchanges, and by evaluating its phenotype changes in vitro and in mice. The disruption of fexA resulted in a significant alteration in growth rate under aerobic as well as anaerobic conditions. When compared to the wild-type, the fexA mutant exhibited a substantial decrease in motility and cytotoxicity toward intestinal epithelial cell lines in vitro. Furthermore, the intraperitoneal $LD_{50}$ of the fexA mutant was approximately $10^{1}-10^{2}$ times higher than that of parental wild-type. Therefore, it appears that FexA is a novel global regulator controlling numerous genes and contributing to the pathogenesis as well as growth of V. vulnificus.

• Korean Journal of Veterinary Research
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• v.42 no.4
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• pp.505-512
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• 2002

대장균 K99 섬모의 생합성은 8개로 구성된 K99의 특이 유전자의 발현과 숙주유래 인자에 의해 조절되는 다른 유전자들의 발현에 의존된다. 본 연구에서는 K99섬모 유전자군중 제 3지역 발현에 유전조절자의 관련성 여부를 연구하였다. Gel retardation 분석 방법올 통하여 제3지역의 발현에 관련된 유전조절단위를 함유한 fanF 지역의 단백질 인자가 부착됨을 암시하였다. 이 분석방법을 이용한 결과는 또한 이 단백질 인자가 K99 유전자에서 유래되지 않고 대장균 염색체에서 유래됨을 지적하였다. 이를 보다 더 조사하기 위하여 대장균 염색체에 Tn10 transposon 유전자 변이 실험을 수행하였다. K99 유전자군으로부터 제 1지역과 제2지역의 유전자를 제거시키고, 제 3지역의 유전자인 fanG에 transposon TnlacZ를 삽입한 pTL65-1 plasmid을 제작하였다. 이 pTL65-1는 다시 Tn10으로 염색체가 변이된 대장균에 주입하였다. 3개의 pTL65-1 주입된 Tn10 대장균 변이체 내에서 fanG의 발현이 증가되었다. 이들 변이대장균으로부터 Tn10이 어떤 염색체 유전자 부위를 변이 시켰는지 확인하기 위해서 변이부위 유전자를 cloning하여 염기서열을 분석하였다. 이중 2개의 clone이 동일하였으며 지금까지 알려지지 않은 유전자였다. 이들 2개의 변이체 내에서 fanG의 발현은 대조군과 비교해 약 4.2배 증가 되였다. 결론적으로 이들 2개의 clone으로부터 유래된 인자는 지금까지 알려지지 않은 제 3지역의 억제 조절자임을 나타내었다.

• The Plant Pathology Journal
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• v.28 no.4
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• pp.439-445
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• 2012

The chitinase producing Lysobacter enzymogenes C-3 has previously been shown to suppress plant pathogens in vitro and in the field, but little is known of the regulation of chitinase production, or its role in antimicrobial activity and biocontrol. In this study, we isolated and characterized chitinase-defective mutants by screening the transposon mutants of L. enzymogenes C-3. These mutations disrupted genes involved in diverse functions: glucose-galactose transpoter (gluP), disulfide bond formation protein B (dsbB), Clp protease (clp), and polyamine synthase (speD). The chitinase production of the SpeD mutant was restored by the addition of exogenous spermidine or spermine to the bacterial cultures. The speD and clp mutants lost in vitro antifungal activities against plant fungal pathogens. However, the gluP and dsbB mutants showed similar antifungal activities to that of the wild-type. The growth of the mutants in nutrient rich conditions containing chitin was similar with that of the wild-type. However, growth of the speD and gluP mutants was defective in chitin minimal medium, but was observed no growth retardation in the clp and dsbB mutant on chitin minimal medium. In this study, we identified the four genes might be involved and play different role in the production of extracellular chitinase and antifungal activity in L. enzymogenes C-3.

• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1609-1616
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• 2017

The complex roles of cell surface modification in the biofilm formation of Campylobacter jejuni, a major cause of worldwide foodborne diarrheal disease, are poorly understood. In a screen of mutants from random transposon mutagenesis, an insertional mutation in the eptC gene (cj0256) resulted in a significant decrease in C. jejuni NCTC11168 biofilm formation (<20%) on major food contact surfaces, such as polystyrene and borosilicate glass, when compared with wild-type cells (p < 0.05). In C. jejuni strain 81-176, the protein encoded by eptC modified cell surface structures, such as lipid A, the inner core of lipooligosaccharide, and the flagellar rod protein (FlgG), by attaching phosphoethanolamine. To assess the role of eptC in C. jejuni NCTC11168, adherence and motility tests were performed. In adhesion assays with glass surfaces, the eptC mutant exhibited a $0.77log\;CFU/cm^2$ decrease in adherence compared with wild-type cells during the initial 2 h of the assay (p < 0.05). These results support the hypothesis that the modification of cell surface structures by eptC affects the initial adherence in biofilm formation of C. jejuni NCTC11168. In motility tests, the eptC mutant demonstrated reduced motility when compared with wild-type cells, but wild-type cells with the transposon inserted in a gene irrelevant to biofilm formation (cj1111c) also exhibited decreased motility to a similar extent as the eptC mutant. This suggests that although eptC affects motility, it does not significantly affect biofilm formation. This study demonstrates that eptC is essential for initial adherence, and plays a significant role in the biofilm formation of C. jejuni NCTC11168.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.134-134
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• 1993

Tn3 Transposon을 이용한 Shuttle Mutagenesis방법으로 효모의 Genome 상에 무작위적으로 $\beta$-gal 표지 유전자를 삽입하고 효모생활사의 각 세포시기 마다 특이하게 발현되는 유전자를 X-Gal plate상에서 찾아내고 이들 효모 유전자의 단백질이 세포내에 어떤 위치에 분포하는가를 간접 면역현미경법으로 추적해보았다. 먼저 효모의 genomic library를 38bp의 Tn3 Termial repeat를 가지고 있지 않은 pHSS6 Vector에 patial fill-in 방법으로 조성하였으며 최종적으로 20 Genome equivalent에 해당하는 18개 Pool의 genomic library를 만들었다. 이들 library를 조사하여 본 결과 모든 클론이 평균 3kb 크기의 insert를 가지고 있었으며 이는 99.99%의 효묘 genome을 대표하였다. 특정한 유전자의 발현을 알아보기 위해 먼저 mini-Tn3로 shuttle mutagenesis를 실시하고 vegetative growth동안 발현되는 유전자를 X-gal을 사용하여 골라내었다. 지금까지 16823개의 클론을 조사하였는데 이중 13%에 해당하는 2187개가 X-gal plate상에서 양성반응을 보여주었다. 양성반응을 보여주는 융합단백질의 세포내 분포틀 anti-$\beta$-galactosidase 항체를 사용하여 추적해보았다. 항체론 이용한 형광염색결과 약 70%의 세포가 background이상의 염색을 보여주었으며 이중 novel한 염색 pattern을 나타내는 클론도 다수 탐지되었다. 이상의 결과를 종합하면 Tn3틀 이용한 Shuttle Mutagenesis 방법으로 지금까지 전통적인 유전학적인 접근 방식으로 탐지되지 않았던 다수의 새로운 효모 유전자를 찾아낼 수 있을 것으로 사료된다.tamine제중 triprolidine이 $K_{M}$ /K$_{H}$ 비가 가장 높았고 diphenidol이 가장 낮았다. 이상의 결과로 보아 항 histamine제의 muscarinic receptor 차단작용은 이들 약물의 항 alleragy 효과에 필요한 작용이 아니며 본 실험에서 추정된 항 histamine제의 H$_1$-receptor와 muscarinic receptor에 대한 상대적 역가는 이들 약물의 선택과 평가에 중요한 지표가 될수 있을 것으로 생각된다.ing ischemic insults. The nature of the receptor is being explored by molecular genetic techniques, and we have recently cloned two of the major subunits; some of the data will be presented.LIFO, 우선 순위 방식등을 선택할 수 있도록 확장하였다. SIMPLE는 자료구조 및 프로그램이 공개되어 있으므로 프로그래머가 원하는 기능을 쉽게 추가할 수 있는 장점도 있다. 아울러 SMPLE에서 새로이 추가된 자료구조와 함수 및 설비제어 방식등을 활용하여 실제 중형급 시스템에 대한 시뮬레이션 구현과 시스템 분석의 예를 보인다._3$", chain segment, with the activation energy of carriers from the shallow trap with 0.4[eV], in he amorphous regions.의 증발산율은 우기의 기상자료를 이용하여 구한 결과 0.05 - 0.10 mm/hr 의 범위로서 이로 인한 강우손실량은 큰 의미가 없음을 알았다.재발이 나타난 3례의 환자를 제외한 9례 (75%)에서는 현재까지 재발소견을 보이지 않고 있다.

• Applied Biological Chemistry
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• v.48 no.4
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• pp.345-351
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• 2005

To access the natural products of uncultured microorganisms, we constructed and screened the metagenomic DNA libraries by using a cosmid vector and DNA inserts isolated directly from soil. Initial screening of the libraries in Escherichia coli resulted in the isolation of several clones that produce a dark brown color when grown in LB medium. One of the positive clones, designed pYS85C, was transposon mutagenized and the DNA surrounding the transposon insertions in cosmids that no longer conferred the production of brown pigment to E. coli was sequenced. Annotation of the pYS85C sequence obtained from the transposon mutagenesis experiment indicated a single 393 amino acid open reading frame (ORF) with a molecular mass of about 44.5 kDa, predicted to be a 4-hydroxyphenylpyruvate dioxygenases (HPPDs), was responsible for the observed brown pigment. In a BLAST search against deposited sequence, the translated protein from this ORF showed moderate-level identity (>60%) to the other known HPPDs and was most conserved in the C-terminal region of the protein. These results show that genes involved in natural product synthesis can be cloned directly from soil DNA and expressed in a heterologous host, supporting the idea that this technology has the potential to provide novel natural products from the wealth of environmental microbial diversity and is a potentially important new tool for drug discovery.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1040-1043
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• 2008

Klebsiella oxytoca CCUG 15788 is resistant to $Ni^{2+}$ at a concentration of 10 mM and grows in an inducible manner when exposed to lower concentrations of $Ni^{2+}$. The complete genomic sequence of a 4.2-kb HindIII-digested fragment of this strain was determined from genomic DNA. It was shown to contain four nickel resistance genes (nirA, nirB, nirC, and nirD) encoding transporter and transmembrane proteins for nickel resistance. When the plasmid pKOHI4, encoding nirABCD, was transformed into Escherichia coli JM109, the cells were able to grow in Tris-buffered mineral medium containing 3 mM nickel. TnphoA'-1 insertion mutants in the four nickel genes nirA, nirB, nirC, and nirD showed nickel sensitivity. The nir genes were heterogeneously expressed in E. coli, suggesting functional roles of these genes in nickel resistance.