• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 추계학술대회 및 정기총회
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• pp.23-23
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• 2015

Rice blast disease caused by M. oryzae is the most devastating fungal disease in rice. During the infection process, M. oryzae secretes a large number of glycosyl hydrolase (GH) proteins into the apoplast to digest host cell wall and assist fungal ingress into host tissues. In this study, we identified a novel M. oryze arabinofuranosidase B (MoAbfB) which is secreted during fungal infection. Live-cell imaging exhibited that fluorescent labeled MoAbfB was highly accumulated in fungal invasive structures such as appressorium, tips of penetration peg, biotrophic interfacial complex (BIC), as well as invasive hyphal tip. Deletion of MoAbfB mutants extended biotrophic phase followed by enhanced disease severity, whereas, over-expression of OsMoAbfB mutant induced rapid defense responses and enhanced rice resistance to M. oryzae infection. Furthermore, exogenous treatment of MoAbfB protein showed inhibition of fungal infection via priming of defense gene expression. We later found that the extract of MoAbfB degraded rice cell wall fragments could also induce host defense activation, suggesting that not MoAbfB itself but oligosaccharides (OGs) derived from MoAbfB dissolved rice cell wall elicited rice innate immunity.

• 한국식물병리학회지
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• 제10권2호
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• pp.83-91
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• 1994

Stem tissues of tomato plants (cv. Kwanyang) inoculated with Phytophthora capsici were examined by light and electron microscopy to compare early cytological differences between comaptible and incompatible interactions of tomatoes with the fungus. Twenty four hours after inoculation, the compatible isolate S 197 colonized severely the epidermis, cortex, and xylem vessels of stem tissue, whereas only few fungal cells colonized the stem tissues inoculated with the incompatible isolate CBS 178.26. Fragmented plasma membrane, distorted chloroplast, degraded cell wall, remnants of host cytoplasm were early ultrastructural features of the damaged host cell observed both in the compatible and incompatible interaction, a number of vesicles were distributed in the space between fungal cell walls and plasma membrane. The degradation of host cell walls by P. capsici was more pronounced in the compatible than the incompatible interactions. The incompatible interactions of tomato cells with P. capsici were characterized by formation of host cell wall apposition in the cortical parenchyma cells, indicating that the apposition of electron-dense material from the host cell walls may function as a plant defense reaction to the fungus. The fungal cells encased by wall appositions had abnormal cytoplasm and separated plasma membranes. The haustorium which formed from the fungal hyphae did not further penetrate through the host wall apposition and cytoplasmic aggregation, especially in the incompatible reactions. In contrast, the haustorium of the compatible isolate S 197 was not encased by wall appositions.

• 약학회지
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• 제43권4호
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• pp.502-508
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• 1999

Chitin is an important structural component of fungal cell wall and is synthesized by chitin synthase I, II, and III. The chitin synthase II is an essential enzyme for the formation of primary septum in Saccharomyces cerevisiae. Therefore, specific inhibitors of this enzyme might block the formation of fungal cell wall and could be used as effective antifungal agents. To search chitin synthase IIinhibitors from natural products, 67 plants were extracted with methanol and examined for the inhibitory activities against chitin synthase II of S. cerevisiae by our cell free assay system. As a result, the extracts from 16 plants showed more than 70% inhibition at the concentration of $280{\;}\mu\textrm{g}/ml$. Of note, Laurus nobilis (81.4%), Lonicera maackii (81.5%), Berchemia berchemiaefolia (82.9%), Koelreuteria paniculata (87.9%), Chamaecyparis pisifera (86%) and Taxus cuspidata (83.9%) inhibited strogly the chitin synthase IIactivity.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1998년도 The 12th Symposium on Plant Biotechnology Vol.12
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• pp.10-18
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• 1998

For improvement of plants in disease resistance, it is most important to elucidate the mechanism to perceive and respond to the signal molecules of invaders. A model system with pea and its pathogen, Mycosphaerella pinodes, showed that the fungal elicitor induced defense responses in all plant species tested but that the suppressor of the fungus blocked or delayed the expression of defense responses and induced accessibility only in the host plant. In the world, many researchers believe that the pathogens` signals are recognized only on the receptors in the plasma membranes. Though we found that the ATPase and polyphosphoinositide metabolism in isolated plasma membranes responded to these fungal signals, we failed to detect specific actions of the suppressor in vitro on these plasma membrane functions. Recently, we found that ATPase (NTPases) and superoxide generating system in isolated cell wall were regulated by these fungal signals even in vitro, especially, by the suppressor in a strictly species-specific manner and also that the cell wall alone prepared an original defense system. The effects of both fungal signals on the isolated cell wall functions in vitro coincide perfectly with those on defense responses in vivo. In this treatise, we discuss the key role of the cell wall, which is plant-specific and the most exterior organelle, in determining host-parasite specificity and molecular target for improvement of plants.

• Molecules and Cells
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• 제28권4호
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• pp.403-406
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• 2009

Rev is an essential regulatory protein for HIV-1 replication. Rev (11-20) is known as the significant region regarding the function of a nuclear entry inhibitory signal (NIS) of Rev. In this study, anticandidal effects and mechanism of action of Rev (11-20) were investigated. The result exhibited that Rev (11-20) contained candidacidal activities. To understand target site(s) of Rev (11-20), the intracellular localization of the peptide was investigated. The result showed that Rev (11-20) rapidly accumulated in the fungal cell surface. The cell wall regeneration test also indicated that Rev (11-20) exerted its anticandidal activity to fungal plasma membrane rather than cell wall. The fluorescent study using 1,6-diphenyl-1,3,5-hexatriene (DPH) further confirmed the membrane-disruption mechanism(s) of Rev (11-20). The present study suggests that Rev (11-20) possesses significant potential regarding therapeutic agents for treating fungal diseases caused by Candida species in humans.

• Journal of Microbiology and Biotechnology
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• 제19권6호
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• pp.573-581
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• 2009

The complex enzyme pool secreted by the phytopathogenic fungus Fusarium graminearum in response to glucose or hop cell wall material as sole carbon sources was analyzed. The biochemical characterization of the enzymes present in the supernatant of fungal cultures in the glucose medium revealed only 5 different glycosyl hydrolase activities; by contrast, when analyzing cultures in the cell wall medium, 17 different activities were detected. This dramatic increase reflects the adaptation of the fungus by the synthesis of enzymes targeting all layers of the cell wall. When the enzymes secreted in the presence of plant cell wall were used to hydrolyze pretreated crude plant material, high levels of monosaccharides were measured with yields approaching 50% of total sugars released by an acid hydrolysis process. This report is the first biochemical characterization of numerous cellulases, hemicellulases, and pectinases secreted by F. graminearum and demonstrates the usefulness of the described protein cocktail for efficient enzymatic degradation of plant cell wall.

• Asian-Australasian Journal of Animal Sciences
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• 제9권3호
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• pp.303-307
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• 1996

The degree of autolysis and presence of cell-wall degrading enzymes in an anaerobic ruminal fungus, Piromyces communis OTSI, grown in liquid medium, was monitored to evaluate the effect of self-digestion on fungal biomass. After a 30 days incubation period fungal dry weight decreased by 45% and the cell wall component chitin decreased by 22%. Chitinase activity detected in the supernatant was mainly of the endotype and peaked at day 6 of the incubation. ${\beta}-1$, 3-glucanase was detected from day 4 and increased throughout the incubation period. Autolysis was a slow process, and under natural conditions it is unlikely that it plays a significant role in the degradation of the spent fungal vegetative stage in the rumen.

• 한국균학회지
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• 제35권1호
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• pp.1-10
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• 2007

세포벽은 진균류의 생존과 삼투안전성 유지에 필수적인 구조체로, 세포부착성 단백질이나 가수분해효소 등과 같은 생물학적 활성을 갖는 다양한 단백질이 결합하거나 그 속에 자리잡고 작용할 수 있게 한다. 최근 효모류인 Saccharomyces cerevisiae와 사상균인 Aspergillus nidulans에서 세포 내 단백질 분비 소낭의 하나인 COPI 소낭을 구성하는 ${\alpha}-COP$ 단백질에 돌연변이가 일어날 경우, 온도의존적 삼투감수성이 나타나는 것으로 밝혀졌다. 이러한 사실은 ${\alpha}-COP$이 베타-1,3-글루칸 합성효소 복합체를 구성하는 단백질과 세포벽 단백질의 이송과정에 중요한 역할을 함으로써 세포벽 안정성 유지에 기여함을 시사하는 것이다. 본 총설에서는 세포 내 단백질 이송기구 중에서도 COPI 소낭을 구성하는 ${\alpha}-COP$과 균류의 세포벽 형성과정과의 관계에 대하여 기술하는 한편, 단백질 분비기구에 결손이 생긴 돌연변 이주를 이용한 세포벽 합성기작에 대한 기초 및 응용연구의 가능성에 대하여 검토하여 보았다.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.967-973
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• 2020

The fungal cell wall is a major target of antifungals. In this study, we report the antifungal activity of an ethanol extract from Aucklandia lappa against Candida albicans. We found that the extract caused cell wall injury by decreasing chitin synthesis or assembly and (1,3)-β-D-glucan synthesis. A sorbitol protection assay demonstrated that the minimum inhibitory concentration (MIC) of the A. lappa extract against C. albicans cells increased eight-fold from 0.78 to 6.24 mg/ml in 72 h. Cell aggregates, which indicate damage to the cell wall or membrane, were commonly observed in the A. lappatreated C. albicans cells through microscopic analysis. In addition, the relative fluorescence intensities of the C. albicans cells incubated with the A. lappa extract for 3, 5, and 6 h were 92.1, 84.6, and 79.8%, respectively, compared to the controls, estimated by Calcofluor White binding assay. This result indicates that chitin content was reduced by the A. lappa treatment. Furthermore, synthesis of (1,3)-β-D-glucan polymers was inhibited to 84.3, 79.7, and 70.2% of that of the control treatment following incubation of C. albicans microsomes with the A. lappa extract at a final concentration equal to its MIC, 2× MIC, and 4× MIC, respectively. These findings suggest that the A. lappa ethanol extract may aid the development of a new antifungal to successfully control Candidaassociated disease.

• Journal of Microbiology and Biotechnology
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• 제32권1호
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• pp.37-45
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• 2022

The fungal cell wall and membrane are the principal targets of antifungals. Herein, we report that myricetin exerts antifungal activity against Candida albicans by damaging the cell wall integrity and notably enhancing the membrane permeability. In the presence of sorbitol, an osmotic protectant, the minimum inhibitory concentration (MIC) of myricetin against C. albicans increased from 20 to 40 and 80 ㎍/ml in 24 and 72 h, respectively, demonstrating that myricetin disturbs the cell wall integrity of C. albicans. Fluorescence microscopic images showed the presence of propidium iodide-stained C. albicans cells, indicating the myricetin-induced initial damage of the cell membrane. The effects of myricetin on the membrane permeability of C. albicans cells were assessed using crystal violet-uptake and intracellular material-leakage assays. The percentage uptakes of crystal violet for myricetin-treated C. albicans cells at 1×, 2×, and 4× the MIC of myricetin were 36.5, 60.6, and 79.4%, respectively, while those for DMSO-treated C. albicans cells were 28.2, 28.9, and 29.7%, respectively. Additionally, myricetin-treated C. albicans cells showed notable DNA and protein leakage, compared with the DMSO-treated controls. Furthermore, treatment of C. albicans cells with 1× the MIC of myricetin showed a 17.2 and 28.0% reduction in the binding of the lipophilic probes diphenylhexatriene and Nile red, respectively, indicating that myricetin alters the lipid components or order in the C. albicans cell membrane, leading to increased membrane permeability. Therefore, these data will provide insights into the pharmacological worth of myricetin as a prospective antifungal for treating C. albicans infections.