抗菌肽OH-CATH对大肠杆菌Escherichia coli的作用

OH-CATH是眼镜王蛇中新发现的cathelicidin家族抗菌肽.它在1%NaCI存在的条件下对多种细菌都有较强的抗菌活性,同时,在高浓度下对人红细胞无溶血活性.OH-CATH足开发新型抗菌药物的优良模板.蜊明OH-CATH的作用机理及其对微生物的选择性,对研发以OH-CATH为先导结构的药物研发有十分重要的意义.本文利用扫描电镜以及透射电镜对OH-CATH与革兰氏阴性菌一大肠杆菌ATCC 25922相互作用的效应研究.结果揭示:OH-CATH对大肠杆菌的作用涉及到3个步骤.首先,OH-CATH借助其带正电的氨基酸残基附着到细菌带负电荷的细胞壁:然后,附着的OH-CATH在达剑一定浓度后发生聚集,以孔道彤成的方式破坏细菌的膜结构;最终,由十细菌膜的损坏,膜的渗透性被破坏,胞内内含物释放造成细菌死亡.

Effects of the Antimicrobial Peptide OH-CATH on Escherichia coil

OH-CATH is a novel cathelicidin identified from king cobra. It showed strong antibacterial activity against various bacteria in the presence of 1% NaCi and no haemolytic activity toward human red blood cells even at a high concentration. OH-CATH might serve as model molecules for the development of antimicrobiai drugs. Understanding the action mechanism of OH-CATH and the reason for its selectivity against microbes is very important for this purpose. The bactericidal effect of the king cobra antimicrobial peptide OH-CATH on Gram-negative Escherichia coli (ATCC 25922) is observed by scanning electron microscopy (SEM) and transmitted electron microscopy (TEM). The SEM and TEM results suggested that the bactericidal mechanism of OH-CATH against Escherichia coil happened in three steps. Firstly, OH-CATH attached to the negatively charged bacterial wall by positively charged amino acid residues. In the second step, the accumulated OH-CATH aggregated and damaged the bacteria membrane in a pore-forming manner. In the last step, with the damage of cell permeability, the contents of the cells were released and eventually cells died.