抗菌肽Tachyplesin Ⅰ及衍生物对大肠杆菌细胞膜作用机制的对比研究

Comparative Study on the Membrane Action Mechanism of Tachyplesin Ⅰ and Its Analogue on Escherichia coli

本研究通过测定抗菌肽tachyplesinⅠ(TPⅠ)及其衍生肽TPⅠ-Y4对脂质体膜的作用模式,以及作用大肠杆菌后对细菌表面电位、疏水性及内、外膜渗透性和离子泄漏率的影响,对比探究了两个肽以细菌细胞膜为靶点的抑菌机理。结果表明:TPⅠ/TPⅠ-Y4作用后的大肠杆菌表面电位升高,表面疏水性增强,TPⅠ-Y4引起电位升高和疏水性增强稍高于TPⅠ。TPⅠ/TPⅠ-Y4均能在插入磷脂双分子层时扰乱脂质体膜释放出钙黄绿素,TPⅠ-Y4引起荧光素的泄漏率更高,但它并不完全破裂脂质体膜。TPⅠ/TPⅠ-Y4均能增加细菌内、外膜的通透性,相比之下,TPⅠ-Y4诱导的外膜渗透性较强,对细胞质膜的破坏作用较大,引起离子以及胞内大分子的泄漏量较多。TPⅠ-Y4对大肠杆菌细胞膜产生了更大的破坏作用可能是其抑菌活性相比于TPⅠ显著提高的主要原因。

The action mechanism of antimicrobial peptide tachyplesin Ⅰ(TP Ⅰ) and its analogue TP Ⅰ-Y4 targeted the cell membrane of Escherichia coli have been studied by exploring the action mode of both peptides on the liposome membrane, the effect on the bacteria surface potential, hydrophobicity, the permeability of inner and outer membrane, and ion leakage after two peptides treated E.coli. The results showed that TP Ⅰ/TP Ⅰ-Y4 induced the increase of surface potential and hydrophobicity of E.coli. TP Ⅰ-Y4 caused a slightly higher potential and hydrophobicity enhancement than TP Ⅰ. Both peptides could disturb the liposome membrane causing the calcein leakage during peptides crossing phospholipids bilayer, TP Ⅰ-Y4 caused more fluorescein leakage, but it did not completely collapse the liposome membrane. TP Ⅰ/TP Ⅰ-Y4 obviously increased the inner and outer membrane permeability of bacteria, in contrast, TP Ⅰ-Y4 induced stronger outer membrane permeability, greater damage to the plasma membrane, causing more leakage of ions and intracellular macromolecules. TP Ⅰ-Y4 had a greater destructive effect on E.coli cell membrane, which may be the main reason for the significant improvement of its antibacterial activity compared with TP Ⅰ.