• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2303-2309
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• 2007

Expressed protein ligation (EPL) technique, joining recombinantly expressed proteins to polypeptides, has been widely adopted for addressing various biological questions and for drug discovery. However, joining two recombinant proteins together is sometimes difficult when proteins are expressed insoluble and unrefoldable, because ligation-active proteins via intein-fusion are obtainable when they are folded correctly. We overcame this limitation coexpressing target protein with additional methionine aminopeptidase (MAP) which enhances removal of the initiation methionine of recombinantly expressed protein. Our approach demonstrated that two domains of 46 kDa 5-Enolpyruvylshikimate-3-phosphate (EPSP) synthase, a target of herbicide glyphosate, were successfully joined by native chemical ligation, although its C-terminal domain was expressed as an inclusion body. The intein-fused N-terminal fragment of EPSP synthase (EPSPSN, residues 1-237) was expressed and the ligation-active thioester tagged N-terminal fragment (EPSPSN-thioester) was purified using a chitin affinity chromatography and mercapto-ethanesulphonate (MESNA) as intein thiolysis reagent. Its Cterminal fragment (EPSPSC, residues Met237-238CYS-427), expressed as an inclusion body, was prepared from an additional MAP-expressing strain. Protein ligation was initiated by mixing ~1 mM of EPSPSN-thioester with ~2 mM of EPSPSCCYS (residues 238CYS-427). Also we found that addition of 2% thiophenol increased the ligation efficiency via thiol exchange. The ligation efficiency was ~85%. The ligated full-length EPSP synthase was dissolved in 6 M GdHCl and refolded. Circular dichroism (CD) and enzyme activity assay of the purified protein showed that the ligated enzyme has distinct secondary structure and ~115% specific activity compared to those of wild-type EPSP synthase. This work demonstrates rare example of EPL between two recombinantly expressed proteins and also provides hands-on protein engineering protocol for large proteins.

• The Plant Pathology Journal
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• 제28권4호
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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.

• Mycobiology
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• 제46권2호
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• pp.154-158
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• 2018

Bitter rot caused by the fungal genus Colletotrichum is a well-known, common disease of apple and causes significant yield loss. In 2013, six fungal strains were isolated from Fuji apple fruits exhibiting symptoms of bitter rot from Andong, Korea. These strains were identified as Colletotrichum fructicola and C. siamense based on morphological characteristics and multilocus sequence analysis of the internal transcribed spacer rDNA, actin, calmodulin, chitin synthase, and glyceraldehyde-3-phosphate dehydrogenase Pathogenicity tests confirmed the involvement of C. fructicola and C. siamense in the development of disease symptoms on apple fruits. This is the first report of C. fructicola and C. siamense causing bitter rot on apple fruit in Korea.

• Mycobiology
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• 제48권1호
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• pp.75-79
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• 2020

Anthracnose is one of the major problems for cultivating many crops, including vegetables, fruits, and trees. It is a continual threat for fruits grower worldwide. Colletotrichum fructicola was isolated from Shine Muscat berries showing typical anthracnose symptom in Korea. It was identified as C. fructicola based on morphology, pathological signs and concatenated sequences of internal transcribed spacer region of rDNA, glyceraldehyde-3-phosphate dehydrogenase, β-tubulin-2, chitin synthase-1, calmodulin, and the Apn2-Mat1-2 intergenic spacer and partial mating type (Mat1-2) gene. To the best of our knowledge, this is the first report first report of anthracnose of Shine Muscat caused by C. fructicola in Korea.

• Mycobiology
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• 제48권4호
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• pp.321-325
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• 2020

A Colletotrichum species was isolated from leaves of Cymbidium exhibiting symptoms of anthracnose. In this study, the isolates obtained were identified based on recent taxonomic approaches for the genus Colletotrichum. The identity of the causal pathogen was confirmed using morphological data and phylogenetic analysis of combined multi-gene dataset (internal transcribed spacer, glyceraldehyde 3-phosphate dehydrogenase, chitin synthase-1, actin, histone3, beta-tubulin, and calmodulin). Pathogenicity testing revealed that the isolates were pathogenic to Cymbidium. Based on these results, the fungal pathogen occurring on Cymbidium orchids was identified as Colletotrichum cymbidiicola, which is a newly recorded species in Korea.

• 한국균학회지
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• 제52권2호
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• pp.135-143
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• 2024

Lindera obtusiloba Blume, a shrub prevalent in the understory vegetation of the deciduous forests in East Asia and Korea, is known for its pharmacological properties, including antioxidant, anti-allergic, and anti-inflammatory activities. Endophytic fungi were isolated from surface-sterilized twigs and leaves of L. obtusiloba collected from Samcheok-si and Jecheon-si in Korea. The fungal strains were identified based on their morphological characteristics and molecular analyses using DNA markers such as internal transcribed spacer, large subunit rDNA, β-tubulin, chitin synthase, and glyceraldehyde-3-phosphate dehydrogenase. Here, we report two new records of endophytic fungi isolated from L. obtusiloba in Korea: Colletotrichum citricola and Valsa ceratophora. These results enhance our understanding of the diversity of endophytic fungi in L. obtusiloba and contribute to enhancing our knowledge of fungal biodiversity in Korea.

• 한국균학회지
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• 제52권2호
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• pp.109-114
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• 2024

Anthracnose fruit rot (AFR) has been observed in greenhouses during the harvesting period in the Chungnam Province of South Korea. Fruits infected inside the greenhouse show black or brown spots, orange conidial masses and in some areas of the infected parts, white fungal growths are visible. The size of these spots gradually expands, leading to the necrosis of the fruits and flowers. Three isolates were obtained from infected fruits and identified as strains of the Colletotrichum acutatum species complex based on morphological characteristics. Multilocus sequence analysis of actin, chitin synthase, glyceraldehyde-3-phosphate dehydrogenase genes, and internal transcribed spacer rDNA regions revealed that the isolates belong to a monophyletic group with the type strain of C. nymphaeae. This is the first time C. nymphaeae has been confirmed in strawberry fruit in Korea.

• 한국키틴키토산학회지
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• 제22권3호
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• pp.185-193
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• 2017

Red tide Heterosigma akashiwo (H. akashiwo), a microscopic alga of the class Raphidophyceae, causes extensive damage to all marine ecosystems. It is essential to reduce the damage to marine ecosystems for them to be used as a resource. In this study, we used organic solvent fractionation to obtain an ethyl acetate-methanol extract from H. akashiwo (HAEM80) and then evaluated its anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and a zebrafish model. HAME80 markedly inhibited the production of nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$). It also down-regulated the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and decreased the secretion of interleukin-$1{\beta}$ ($IL-1{\beta}$) in LPS-stimulated RAW 264.7 cells. HAME80 reduced yolk edema and improved the survival rate of LPS-stimulated zebrafish embryos; in addition, the extract significantly reduced the production of ROS and NO and attenuated cell death in this model. Gas chromatography-mass spectrometry (GC-MS) of the extract was used to confirm the identity of peaks 1-20. Taken together, our data suggest that H. akashiwo is a beneficial anti-inflammatory agent.

• 한국균학회지
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• 제47권4호
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• pp.393-406
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• 2019

2017년 8월경, 강원도 홍천군, 정선군, 평창군 소재 무 재배 포장에서 잎자루와 잎의 주맥에 형성된 탄저병 병징이 관찰되었다. 회색 내지 짙은 갈색을 띤 1-2 mm 크기의 점무늬가 아래 잎과 잎의 주맥에 형성되었다. 이러한 점무늬는 점차 확대되고 합쳐지면서 갈색을 띤 불규칙한 병반으로 나타났다. 병든 무 잎에서 10개의 Colletotrichum균을 분리하였다. 분리 균주의 형태적 특성과 internal transcribed spacers and intervening 5.8S rDNA (ITS), partial beta-tubulin gene (TUB2), partial actin gene (ACT) 및 partial chitin synthase-1 gene (CHS-1) 부위를 사용한 다자위 분자 계통 분석(multilocus molecular phylogenetic analysis)에 의해 8개 균주는 Colletotrichum higginsianum, 2개 균주는C. truncatum으로 동정되었다. 무(시래기무, 오사리무)와 배추(품종: 추노, 스마트)를 대상으로 상처와 무상처로 구분하여 포자현탁액을 떨어뜨려서 접종하는 방법을 사용하여 병원성 검정을 수행하였다. 무에서는C. truncatum 1개 균주를 제외하고 상처와 무상처 접종에서 모두 병징을 나타냈고, 배추의 경우는C. higginsianum 접종구에서만 상처의 유무에 관계없이 병이 발생하였다. 국내에는 기존에 C. higginsianum은 무와 배추의 탄저병균으로 보고되었으며, C. truncatum에 의한 무 탄저병의 발생은 본 연구에서 국내 최초로 보고한다.

• 농약과학회지
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• 제6권2호
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• pp.105-109
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• 2002

Bezoylphenyl urea계 신규 살충제인 1-(2,6-difluorobenzoyl)-3-(3,5-bistrifluoromethyl-2-chlorophenyl) urea (DBI-3204, HW-3204)를 생산하기 위하여 경제적인 합성법을 확립하였다. 특히 3단계 합성공정에 사용하는 용매를 사염화탄소로 단순화 시켰다. 필수적인 중간체인 3,5-bis(trifluorornethyl)-2-chloroaniline을 92%로 선택적으로 합성하였으며, 2,6-difluorobenzoylisocyanate는 95%, DBI-3204는 약 90%의 좋은 수율로 합성하였다.