• 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.

• 생명과학회지
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• 제26권12호
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• pp.1409-1414
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• 2016

동애등에(Hermetia illucens)를 포함한 곤충은 불량환경에서 오랜 진화의 역사를 통해 병원균 침입에 대응하기 위하여 강력한 항균 펩타이드를 발현하는 선천성 면역기전을 보유하고 있다. 동애등에 생체 내 항균펩타이드를 인위적으로 유도하기 위하여, E. faecalis 포함한 5종의 세균을 한방침에 묻혀 주사하였다. 5종 세균에 의해 면역이 유도된 동애등에로부터 혈림프를 채취하여 각 세균에 따른 항균펩타이드 유도효과에 의한 항균활성을 그람양성균인 S. aureus와 그람음성균인 E. coli에 대해 비교 분석하였다. 그 결과, 고초균인 B. subtilis은 5종 세균 중 그람양성 및 음성균 둘 다에 대해서 가장 높은 항균활성을 나타내었다. B. subtilis ($1{\times}10^9cfu/ml$)에 의해 면역이 유도된 동애등에는 주사 후 24시간째 가장 강한 항균활성을 나타내었다. 또한 B. subtilis에 의해 면역이 유도된 동애등에는 가금류의 주요 병원균인 S. enteritidis, S. typhimurium 및 S. pullorum에 대해서도 높은 항균활성을 나타내었다. 이상의 결과로써, B. subtilis에 의해 면역이 유도된 동애등에는 가축 성장촉진용 항생제를 대체할 수 있는 사료첨가제로써 매우 유용할 것으로 판단된다.

• Journal of Veterinary Science
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• 제24권3호
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• pp.44.1-44.17
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• 2023

Background: Antibiotic resistance is a significant public health concern around the globe. Antimicrobial peptides exhibit broad-spectrum and efficient antibacterial activity with an added advantage of low drug resistance. The higher water content and 3D network structure of the hydrogels are beneficial for maintaining antimicrobial peptide activity and help to prevent degradation. The antimicrobial peptide released from hydrogels also hasten the local wound healing by promoting epithelial tissue regeneration and granulation tissue formation. Objective: This study aimed at developing sodium alginate based hydrogel loaded with a novel antimicrobial peptide Chol-37(F34-R) and to investigate the characteristics in vitro and in vivo as an alternative antibacterial wound dressing to treat infectious wounds. Methods: Hydrogels were developed and optimized by varying the concentrations of crosslinkers and subjected to various characterization tests like cross-sectional morphology, swelling index, percent water contents, water retention ratio, drug release and antibacterial activity in vitro, and Pseudomonas aeruginosa infected wound mice model in vivo. Results: The results indicated that the hydrogel C proved superior in terms of cross-sectional morphology having uniformly sized interconnected pores, a good swelling index, with the capacity to retain a higher quantity of water. Furthermore, the optimized hydrogel has been found to exert a significant antimicrobial activity against bacteria and was also found to prevent bacterial infiltration into the wound site due to forming an impermeable barrier between the wound bed and external environment. The optimized hydrogel was found to significantly hasten skin regeneration in animal models when compared to other treatments in addition to strong inhibitory effect on the release of pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor-α). Conclusions: Our results suggest that sodium alginate -based hydrogels loaded with Chol-37(F34-R) hold the potential to be used as an alternative to conventional antibiotics in treating infectious skin wounds.