化学合成抗菌肽抑制致病性大肠杆菌F41的分子作用机理

Molecular Mechanisms of Novel Synthetic Analogs of Tachyplesin against Pathogenic Escherichia coli F41

摘要:

本文以化学合成抗菌肽为研究对象，对合成抗菌肽的抑菌活力、抑菌动力学进行研究；通过圆二色谱法评价抗菌肽二级结构的变化；电镜观察抗菌肽对细菌微观结构影响；K+和紫外吸收物质泄漏实验分析抗菌肽对细胞膜通透性影响；DNA凝胶阻滞实验分析抗菌肽与细菌DNA相互作用关系。结果表明：不同抗菌肽的抗菌活力、抑菌动力学存在差异；抗菌活力与抗菌肽浓度、作用时间有关；抗菌肽Tac、TacW、TacV明显改变细胞微观结构，使胞内K+和紫外吸收物质泄漏，细胞膜通透性改变，造成细胞坍塌破裂，进入细胞与DNA结合，产生凝胶阻滞现象。得出结论：抗菌肽作用机理与抗菌肽结构中碱性氨基酸、两亲性氨基酸的比例密切相关，其分子作用机理包括使细胞膜通透性发生变化、改变细菌细胞微观结构、结合基因组DNA，抑制复制、转录等，形成多个作用靶点，是一种多效协同的作用机制。

Abstract:

This study aimed to investigate the antibacterial activity and antibacterial kinetics of synthetic tachyplesins. The changes in the secondary structure of the synthetic peptides were investigated by circular dichroism (CD) spectroscopy, and the effect of synthetic peptides on the microstructure of cells was investigated by electron microscopy. The permeability of the cell membrane was investigated by leakages of K+ ion l and ultraviolet (UV)-absorbing materials, and the interaction between synthetic peptides and genomic DNA was investigated by DNA gel retardation experiment. The results showed that the antibacterial activity and antibacterial kinetics were different in different synthetic tachyplesins, and the antibacterial activity was related with the concentration of tachyplesins and the action time. The cellular microstructure of Escherichia coli was significantly changed by synthetic antimicrobial peptides Tac, TacW, and TacV causing leakages of K+ ions and UV absorbing materials, changes in cell membrane permeability, bacterial cell wall fractures, and cell collapse. At the same time, synthetic antibacterial peptides could bind to genomic DNA and lead to gel retardation. In conclusion, the action mechanism of synthetic tachyplesins is closely related to the ratio of amphiphilic amino acids and basic amino acids in tachyplesins structure. The molecular mechanisms involves multiple effects, including changes in membrane permeability and bacterial cell microstructure, genomic DNA binding, inhibition of replication and transcription, and formation of multiple targets.