Zan Bing, Ulmschneider Martin B, Ulmschneider Jakob P
School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
Department of Chemistry, King's College London, London, UK.
Sci Rep. 2025 Mar 3;15(1):7442. doi: 10.1038/s41598-025-91951-8.
Melittin, a natural peptide found in bees, has been shown to induce pore formation in cell membranes. However, its artificial mutant, MelP5 can do so at concentrations 200 times lower than melittin. The mechanism of the enhanced portion ability is not fully understood. By conducting all-atom molecular dynamics (MD) simulations, we found that MelP5 forms a stable pore that is macro-molecular sized. Our results suggest that the mutation of five amino acids from melittin reduces the electrostatic repulsion between peptides and strengthens hydrophobic interactions between MelP5 and lipid tails, resulting in the formation of a stable and larger pore. Furthermore, we found that cholesterol (CHOL), which occupies 30% in mammalian cell membranes, plays a crucial role in enhancing the pore formation of MelP5. As the amount of CHOL increases, the pore becomes larger, more stable, and forms more quickly. The presence of CHOL also promotes the formation of oligomers, which further support the pore. Our findings indicate that CHOL promotes the insertion of peptides into the membrane and reduces the amount of surface state peptides, thereby stabilizing the pore. These results highlight the important role of CHOL in membrane permeabilization by MelP5 and provide new insights into the mechanism of action of membrane-active antimicrobial peptides.
蜂毒肽是一种在蜜蜂体内发现的天然肽，已被证明能在细胞膜中诱导孔道形成。然而，其人工突变体MelP5在比蜂毒肽低200倍的浓度下就能做到这一点。其增强的成孔能力机制尚未完全了解。通过进行全原子分子动力学（MD）模拟，我们发现MelP5形成了一个大分子尺寸的稳定孔道。我们的结果表明，蜂毒肽五个氨基酸的突变减少了肽之间的静电排斥，并加强了MelP5与脂质尾部之间的疏水相互作用，从而导致形成一个稳定且更大的孔道。此外，我们发现，在哺乳动物细胞膜中占30%的胆固醇（CHOL）在增强MelP5的孔道形成中起关键作用。随着CHOL含量的增加，孔道变得更大、更稳定且形成得更快。CHOL的存在还促进了寡聚体的形成，进一步支撑了孔道。我们的研究结果表明，CHOL促进肽插入膜中并减少表面态肽的数量，从而稳定孔道。这些结果突出了CHOL在MelP5介导的膜通透性中的重要作用，并为膜活性抗菌肽的作用机制提供了新的见解。
