Lin Dongdong, Li Shuangshuang, Li Shiying, Tang Ting, Liu Fengsong
The Key Laboratory of Zoological Systematics and Application, College of Life Sciences, Hebei University, Baoding, China.
Hebei Basic Science Center for Biotic Interaction, Hebei University, Baoding, China.
Insect Mol Biol. 2025 Jun 19. doi: 10.1111/imb.13005.
Antimicrobial peptides (AMPs) are increasingly being recognised as promising alternatives to conventional antibiotics due to their distinctive antimicrobial mechanisms and reduced likelihood of inducing drug resistance. Insects represent a significant source of AMPs. In this study, a potential AMP gene, MdAMP5, was identified based on its strong immunoinducibility and the presence of a signal peptide, and an amphipathic α-helix in the encoded protein. MdAMP5 encoded a 50-amino acid precursor protein with an N-terminal 22-amino acid signal peptide. The calculated molecular mass of the mature protein was 2.92 kDa, with an estimated isoelectric point of 6.23. Structural analyses revealed that the N-terminus of mature MdAMP5 contained an irregularly coiled segment, while the C-terminus featured an amphipathic α-helix with a glycine-lysine residue at the end. Furthermore, the MdAMP5 gene was successfully expressed in the yeast Pichia pastoris, and the recombinant MdAMP5 (rMdAMP5) protein exhibited effective and broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria in vitro and in vivo. Treatment with rMdAMP5 resulted in significant changes in bacterial morphology, including cell lysis and deformation of bacteriophages. In conclusion, this study identified and successfully expressed a novel AMP that showed low cytotoxicity to mammalian cells and high selectivity towards bacterial cells. This research offers a new candidate for therapeutic drug development, and enhances the understanding of the mechanism and application of AMPs.
抗菌肽（AMPs）因其独特的抗菌机制和较低的诱导耐药性可能性，越来越被认为是传统抗生素的有前途的替代品。昆虫是抗菌肽的重要来源。在本研究中，基于其强大的免疫诱导性、信号肽的存在以及编码蛋白中两亲性α-螺旋的存在，鉴定出一个潜在的抗菌肽基因MdAMP5。MdAMP5编码一个由50个氨基酸组成的前体蛋白，其N端有一个22个氨基酸的信号肽。成熟蛋白的计算分子量为2.92 kDa，估计等电点为6.23。结构分析表明，成熟MdAMP5的N端包含一个不规则卷曲的片段，而C端则以一个在末端带有甘氨酸-赖氨酸残基的两亲性α-螺旋为特征。此外，MdAMP5基因在毕赤酵母中成功表达，重组MdAMP5（rMdAMP5）蛋白在体外和体内对革兰氏阳性菌和革兰氏阴性菌均表现出有效的广谱抗菌活性。用rMdAMP5处理导致细菌形态发生显著变化，包括细胞裂解和噬菌体变形。总之，本研究鉴定并成功表达了一种对哺乳动物细胞细胞毒性低、对细菌细胞选择性高的新型抗菌肽。本研究为治疗药物开发提供了一个新的候选物，并增进了对抗菌肽机制和应用的理解。
