• 생명과학회지
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• 제30권1호
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• pp.64-69
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• 2020

꿀벌(Apis mellifera)에는 많은 항균성 펩티드가 있습니다. 그러나 아직 많은 종류의 펩티드를 기능을 알려지지 않았다. 따라서, 알려지지 않은 기능성 펩티드의 특성화가 필요하다. 그래서 우리는 새로운 항균성 펩티드(AMP)를 분석 하였다. 우리는 Apis mellifera에서 total RNA를 분리하고 Illumina HiSeq 2500 차세대 시퀀싱(NGS) 기술을 사용하여 15,314 개의 펩티드 서열을 생성하여 새로운 AMP를 선발 하였다. AMP로서 기능을 가지는 AMP를 선발 하기 위해 AMP 서열의 특성 과 특징을 분석을 기초로 하여 알려지지 않은 펩티드 및 알려진 44 개의 펩티드가 확인 되었다. 그 중에서도 AMP5라는 특성화 되지 않은 펩티드를 선발 하였다. AMP5는 표피, 지방체, 독낭에서 발현된다. 항균 활성을 분석하기 위해 Gram-negative bacteria Escherichia coli KACC 10005 및 Bacillus thuringiensis KACC 10168에 대한 항균 활성을 합성한 AMP5 처리하여 시험 하였다. AMP5는 Gram-negative bacteria Escherichia coli에 대한 항균 활성을 나타냈다(MIC₅₀ = 22.04±0.66 μM). 일벌에 Escherichia coli을 주사했을 때 AMP5는 체내에서 항균성 펩티드로 발현이 높아졌다. 이러한 결과는 Escherichia coli에 대한 항균 활성을 나타냄을 확인하였다.

• 생명과학회지
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• 제31권8호
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• pp.755-760
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• 2021

돼지 설사병은 부종병과 함께 양돈 농가에 막대한 경제적 손실을 입히는 가축질병으로 알려져 있으며, 병원성 대장균의 증식에 의하여 설사 및 대장균 생성 독소에 의한 부종병이 동반된다. 본 연구에서는 항균펩타이드를 포함하는 면역유도누에의 조추출물을 이용하여 돼지 설사 및 부종을 유발하는 F4+ 및 F18ab+ 대장균의 사균체를 제작하고 사균백신으로서 이용가능성을 검토하였다. 면역유도누에 추출물의 항균활성을 환확산법을 통해 분석한 결과 F4+ 및 F18ab+ 대장균에 대하여 높은 활성을 나타내었으며, 평판계수법을 이용하여 대장균의 사균체 생산효율을 분석한 결과 50 mg/ml의 농도를 4℃에서 처리했을 때 가장 높게 나타났다. 또한 제작된 사균체에 대해서 투과전자현미경을 이용하여 분석한 결과 세포질은 유출되고 세포막만이 남아있는 대장균이 확인되었다. 따라서 면역유도누에 추출물을 이용하여 제작된 F4+ 및 F18ab+ 대장균은 부종병 예방을 위한 사균백신으로서 이용가능성이 매우 높을 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1317-1322
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• 2014

Membrane disruption by an antimicrobial peptide (AMP) was investigated by measuring the $^2H$ solid-state nuclear magnetic resonance spectra of 1-palmitoyl-$d_{31}$-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC_$d_{31}$) in mixtures of POPC_$d_{31}$/cholesterol and either magainin 2 or aurein 3.3 deposited on thin cover-glass plates. The line shapes of the experimental $^2H$ solid-state nuclear magnetic resonance (SSNMR) spectra were best simulated by assuming the coexistence of a mosaic spread of bilayers containing pore structures and a fasttumbling isotropic phase or a hexagonal phase. Within a few days of incubation in a hydration chamber, an isotropic phase and a pore structure were induced by magainin 2, while in case of aurein 3.3 only an isotopic phase was induced in the presence of a bilayer phase. After an incubation period of over 100 days, alignment of the bilayers increased and the amount of the pore structure decreased in case of magainin 2. In contrast with magainin 2, aurein 3.3 induced a hexagonal phase at the peptide-to-lipid ratio of 1/20 and, interestingly, cholesterol was not found in the hexagonal phase induced by aurein 3.3. The experimental results indicate that magainin 2 is more effective in disrupting lipid bilayers containing cholesterol than aurein 3.3.

• Journal of Microbiology and Biotechnology
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• 제30권3호
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• pp.382-390
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• 2020

Periplanetasin-4 is an antimicrobial peptide with 13 amino acids identified in cockroaches. It has been reported to induce fungal cell death by apoptosis and membrane-targeted action. Analogs were designed by substituting arginine residues to modify the electrostatic and hydrophobic interactions accordingly and explore the effect of periplanetasin-4 through the increase of net charge and the decrease of hydrophobicity. The analogs showed lower activity than periplanetasin-4 against gram-positive and gram-negative bacteria. Similar to periplanetasin-4, the analogs exhibited slight hemolytic activity against human erythrocytes. Membrane studies, including determination of changes in membrane potential and permeability, and fluidity assays, revealed that the analogs disrupt less membrane integrity compared to periplanetasin-4. Likewise, when the analogs were treated to the artificial membrane model, the passage of molecules bigger than FD4 was difficult. In conclusion, arginine substitution could not maintain the membrane disruption ability of periplanetasin-4. The results indicated that the attenuation of hydrophobic interactions with the plasma membrane caused a reduction in the accumulation of the analogs on the membrane before the formation of electrostatic interactions. Our findings will assist in the further development of antimicrobial peptides for clinical use.

• 한국자기공명학회논문지
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• 제15권1호
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• pp.1-13
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• 2011

9Pbw2 is a 9-mer analog of protaetiamycine derived from the larvae of the beetle Protaetia brevitarsis. Previously, we designed four 9-mer peptide analogues to optimize the balance between the hydrophobicity and cationicity of the peptides and to increase bacterial cell selectivity. Among them, 9Pbw2 has high antibacterial activity without cytotoxicity. The results obtained in previous study suggest that the bactericidal action of 9Pbw2 may be attributed to the inhibition of the functions of intracellular components after penetration of the bacterial cell membrane. In order to understand structure-activity relationships, we determined the three-dimensional structure of 9Pbw2 in 200 mM DPC micelle by NMR spectroscopy. 9Pbw2 has one hydrophobic turn helix from $Trp^3$ to $Arg^8$ and positively charged residues at the N- and C-terminus. This result suggested that positively charged residues from position at the C-terminus in 9Pbw2 may be important for the primary binding to the negatively charged phospholipid head groups in bacterial cell membranes and hydrophobic residues in the middle portion face toward the acyl chains of the hydrophobic lipid in the bacterial cell membrane.

• Journal of Microbiology and Biotechnology
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• 제28권11호
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• pp.1771-1781
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• 2018

The emergence of multidrug-resistant microorganisms, as well as fungal infectious diseases that further threaten health, especially in immunodeficient populations, is a major global problem. The development of new antifungal agents in clinical trials is inferior to the incidence of drug resistance, and the available antifungal agents are restricted. Their mechanisms aim at certain characteristics of the fungus in order to avoid biological similarities with the host. Synthesis of the cell wall and ergosterol are mainly targeted in clinical use. The need for new approaches to antifungal therapeutic agents or development alternatives has increased. This review explores new perspectives on mechanisms to effectively combat fungal infections and effective antifungal activity. The clinical drug have a common feature that ultimately causes caspase-dependent cell death. The drugs-induced cell death pathway is associated with mitochondrial dysfunction, including mitochondrial membrane depolarization and cytochrome c release. This mechanism of action also reveals antimicrobial peptides, the primary effector molecules of innate systems, to highlight new alternatives. Furthermore, drug combination therapy is suggested as another strategy to combat fungal infection. The proposal for a new approach to antifungal agents is not only important from a basic scientific point of view, but will also assist in the selection of molecules for combination therapy.

• Fisheries and Aquatic Sciences
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• 제20권12호
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• pp.31.1-31.11
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• 2017

Background: Liver-expressed antimicrobial peptide-2 (LEAP-2) is an important component of innate immune system in teleosts. In order to understand isoform-specific involvement and regulation of LEAP-2 genes in mud loach (Misgurnus mizolepis, Cypriniformes), a commercially important food fish, this study was aimed to characterize gene structure and expression characteristics of two paralog LEAP-2 isoforms. Results: Mud loach LEAP-2 isoforms (LEAP-2A and LEAP-2B) showed conserved features in the core structure of mature peptides characterized by four Cys residues to form two disulfide bonds. The two paralog isoforms represented a tripartite genomic organization, known as a common structure of vertebrate LEAP-2 genes. Bioinformatic analysis predicted various transcription factor binding motifs in the 5'-flanking regions of mud loach LEAP-2 genes with regard to development and immune response. Mud loach LEAP-2A and LEAP-2B isoforms exhibited different tissue expression patterns and were developmentally regulated. Both isoforms are rapidly modulated toward upregulation during bacterial challenge in an isoform and/or tissue-dependent fashion. Conclusion: Both LEAP-2 isoforms play protective roles not only in embryonic and larval development but also in early immune response to bacterial invasion in mud loach. The regulation pattern of the two isoform genes under basal and stimulated conditions would be isoform-specific, suggestive of a certain degree of functional divergence between isoforms in innate immune system in this species.

• 약학회지
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• 제49권5호
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• pp.422-427
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• 2005

Our previous data showed the protein isolated from Coptidis Rhizoma (CRP) had antifungal activity. In present study, we examined mode of action of the CRP and its activity against subcutaneous candidiasis due to C. albicans yeast cells. Results showed that the CRP blocked hyphal production from yeast form of C. albicans. The CRP also activated RAW 264.7 monocyte/macrophage cell line, which resulted in nitiric oxide (NO) production from the cells. This activation seemed to increase macrophage phagocytosis to destroy the invaders. Like other antimicrobial peptides, CRP was influenced by ionic strength, thus resulting in a decrease of antifungal activity. In murine model of a subcutaneous candidiasis, the sizes of infected areas of the nude mice given the CRP after subcutaneous injection of C. albicans yeast cells to the dorsal skin were $90\%$ less than those of the nude mice groups that received DPBS instead of the CRP. All data indicate that the CRP, which appeared to act like an antimicrobial peptide and to inhibit the morphological transition from blastoconidia, was effec­tive against the subcutaneous disease.

• BMB Reports
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• 제42권8호
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• pp.506-510
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• 2009

The Toll signalling pathway in invertebrates is responsible for defense against Gram-positive bacteria and fungi, leading to the expression of antimicrobial peptides via NF-$\kappa$B-like transcription factors. Gram-negative binding protein 3 (GNBP3) detects beta-1,3-glucan, a fungal cell wall component, and activates a three step serine protease cascade for activation of the Toll signalling pathway. Here, we showed that the recombinant N-terminal domain of Tenebrio molitor GNBP3 bound to beta-1,3-glucan, but did not activate down-stream serine protease cascade in vitro. Reversely, the N-terminal domain blocked GNBP3-mediated serine protease cascade activation in vitro and also inhibited beta-1,3-glucan-mediated antimicrobial peptide induction in Tenebrio molitor larvae. These results suggest that the N-terminal GNBP homology domain of GNBP3 functions as a beta-1,3-glucan binding domain and the C-terminal domain of GNBP3 may be required for the recruitment of immediate down-stream serine protease zymogen during Toll signalling pathway activation.

• Journal of Microbiology and Biotechnology
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• 제31권2호
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• pp.189-196
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• 2021

Periplanetasin-2 from cockroach exhibits broad-spectrum antimicrobial activity. The underlying antibacterial mechanisms rely on the stimulation of reactive oxygen species overproduction to induce apoptotic cell death. A promising strategy to increase the bioavailability of periplanetasin-2 involves reducing the dose through combination therapy with other antibacterials that show synergistic effects. Thus, the synergistic antibacterial activity of periplanetasin-2 with conventional antibacterial agents and its mechanisms was examined against Escherichia coli in this study. Among the agents tested, the combinations of periplanetasin-2 with vancomycin and chloramphenicol exhibited synergistic effects. Periplanetasin-2 in combination with vancomycin and chloramphenicol demonstrated antibacterial activity through the intracellular oxidative stress response. The combination with vancomycin resulted in the enhancement of bacterial apoptosis-like death, whereas the combination with chloramphenicol enhanced oxidative stress damage. These synergistic interactions of periplanetasin-2 can help broaden the spectrum of conventional antibiotics. The combination of antimicrobial peptides and conventional antibiotics is proposed as a novel perspective on treatments to combat severe bacterial infection.