Difference between revisions of "Part:BBa K5332002:Design"

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Di-melittin (anti-inflammatory peptide)

Design Notes

Despite modifications, the inherent cytotoxicity of melittin remains. When applying melittin, introducing amino acid mutations to alter its sequence could further reduce its toxicity to cells, enhancing its safety and applicability without affecting its bioactivity.

Profile

• Name: Di-melittin
• Base Pairs: 228bp

Background

Melittin, as a crucial active component of bee venom, has garnered significant attention in the scientific community for its remarkable anti-inflammatory and immunomodulatory properties. The molecular structure of melittin enables it to effectively intervene in and regulate the human immune response, demonstrating substantial potential in studies of various inflammatory diseases.

In recent years, researchers have gradually unveiled the possible mechanisms of melittin in the treatment of inflammatory bowel disease (IBD) through multiple laboratory studies and animal model experiments. melittin can reduce inflammatory responses by inhibiting the release of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Additionally, it modulates the activity of immune cells, particularly regulatory T cells and macrophages, thereby maintaining balance within the immune system. These mechanisms work synergistically to significantly alleviate intestinal inflammation and aid in restoring normal intestinal function.

In terms of clinical application, melittin shows promise in improving IBD symptoms. However, further research is needed to optimize its safety and efficacy.

The anti-inflammatory principle of melittin

Anti-inflammatory effect

Figure 1:Anti-inflammatory effect of melittin

Reference: Liu Minchen & Du Ruofei, Chinese Journal of Modern Applied Pharmacy, 2023

In terms of anti-inflammatory effects, melittin plays a crucial role in regulating inflammatory signaling pathways. It inhibits the activity of the NF-κB pathway, reducing the expression of inflammatory cytokines such as TNF-α, IL-1β, and IL-6. Melittin can suppress the phosphorylation of IKK and IκB, thereby blocking the nuclear translocation of NF-κB and interfering with inflammatory signal transduction. Additionally, melittin affects the MAPK signaling pathway by inhibiting the phosphorylation of JNK and p38, thus regulating the production of pro-inflammatory cytokines and reducing the activity of inflammatory cells and the secretion of inflammatory mediators. Furthermore, melittin interferes with the JAK/STAT pathway, inhibiting the activity of STAT transcription factors decreasing the secretion of inflammatory cytokines, which helps alleviate inflammatory diseases. Melittin also reduces inflammation by inhibiting Akt phosphorylation, which interferes with the expression of inflammatory proteins and suppresses the production of inflammatory mediators such as COX-2, iNOS, and cPLA2. Additionally, melittin promotes the recruitment of immune cells to the site of inflammation and induces T-cell apoptosis, thereby modulating the immune response and further alleviating inflammation.

Antibacterial effect of melittin

Figure 2:Effect of melittin on cell membrane

Reference: Zhang HQ, Sun C, Xu N, Liu W. The current landscape of the antimicrobial peptide melittin and its therapeutic potential. Front Immunol. 2024 Jan 22;15:

Melittin monomers can attach to the membrane surface and spontaneously integrate into natural or artificial phospholipid bilayers, thereby reducing the rigidity between the polar and non-polar regions and decreasing the permeability barrier. It has been proposed that melittin-induced membrane permeability may result from the formation of toroidal pores or fissures within the membrane.

Figure 3:Anti-fungal mechanisms of melittin

Reference: Memariani, H., & Memariani, M. (2020). Anti-fungal properties and mechanisms of melittin. Applied microbiology and biotechnology, 104(15), 6513–6526.

Melittin affects fungal cells through multiple mechanisms. It externalizes phosphatidylserine and forms cyclic pores, disrupting cell membrane integrity and increasing membrane permeability, leading to an imbalance of intracellular and extracellular substances, such as potassium ion leakage resulting in ionic imbalance. Additionally, Melittin induces apoptosis via a reactive oxygen species (ROS)-mediated mitochondrial/caspase-dependent pathway, inhibiting fungal growth. It also inhibits the activity of (1,3)-β-D-glucan synthase, affecting cell wall stability. Furthermore, Melittin can alter fungal gene expression and cause DNA fragmentation, further disrupting growth and reproduction.

Functional Evolution Design of Melittins

Modification Method

The toxicity of melittin limits its clinical applications, so we have ingeniously modified and optimized the melittin molecule. Specifically, we employed an innovative approach by linking two melittin monomers with a carefully designed linker. This design allows the two peptide monomers to form a stable hairpin structure.

Figure 4：Amino acid sequence and nucleic acid sequence

Figure 5：Possible structural diagram

Modification Results

This modification effectively reduces the cytotoxicity of melittin while significantly enhancing its function as an immune stimulant. This improvement not only increases the safety of melittin in biomedical applications but also enhances its potential value in immunotherapy. The dual optimization allows melittin to be applied in a broader range of clinical settings, offering more ideal therapeutic options and higher treatment efficiency.

References

1 Zhou, Q., Zeng, J., & Liu, Z. (2023). Research Progress in the Treatment of Inflammatory Diseases with Melittin. Chinese Journal of Modern Applied Pharmacy, 40(9), 1270-1277.

2 Zhang HQ, Sun C, Xu N, Liu W. The current landscape of the antimicrobial peptide melittin and its therapeutic potential. Front Immunol, 2024 Jan 22;15:

3 Memariani, H., & Memariani, M. (2020). Anti-fungal properties and mechanisms of melittin. Applied microbiology and biotechnology, 104(15), 6513–6526.

4 Ceremuga M, Stela M, Janik E, Gorniak L, Synowiec E, Sliwinski T, Sitarek P, Saluk-Bijak J, Bijak M. Melittin-A Natural Peptide from Bee Venom Which Induces Apoptosis in Human Leukaemia Cells. Biomolecules. 2020 Feb 6;10(2):247