Andrä Jörg, Herbst Rosa, Leippe Matthias
Department of Biochemistry and Molecular Biology, Chemical Institutes, University of Hamburg, Germany.
Dev Comp Immunol. 2003 Apr;27(4):291-304. doi: 10.1016/s0145-305x(02)00106-4.
Antimicrobial peptides are widespread in animal species and their function as defensive molecules may even have appeared before the evolution of metazoa. The amoeboid protozoon Entamoeba histolytica discharge membrane-permeabilizing polypeptides named amoebapores into the phagosome in which engulfed bacteria are situated as evidenced here by confocal laser microscopy and electron microscopy using specific antibodies. We demonstrate that the purified three isoforms of the amoebic polypeptides exhibit complementary antibacterial activities in vitro. The potency of amoebapores were compared with that of antimicrobial peptides of phylogenetically widespread species by monitoring in parallel their activities against representatives of gram-positive and gram-negative bacteria and liposomes in various assays, and differences in the mechanism of membrane permeabilization became apparent. Northern blot analysis revealed that expression of genes coding for amoebapores and amoebic lysozymes is not dramatically changed upon co-culture of amoebae with bacteria indicating that the antimicrobial arsenal is rather constitutively expressed than induced in these primitive phagocytes.
抗菌肽在动物物种中广泛存在，它们作为防御分子的功能甚至可能在后生动物进化之前就已出现。变形虫原生动物溶组织内阿米巴会将名为溶组织内阿米巴穿孔素的膜通透多肽释放到吞噬体中，吞噬体中存在被吞噬的细菌，共聚焦激光显微镜和使用特异性抗体的电子显微镜观察结果证实了这一点。我们证明，纯化的三种溶组织内阿米巴多肽同工型在体外表现出互补的抗菌活性。通过在各种试验中并行监测溶组织内阿米巴穿孔素和系统发育广泛物种的抗菌肽对革兰氏阳性菌、革兰氏阴性菌和脂质体的活性，比较了溶组织内阿米巴穿孔素的效力，膜通透机制的差异变得明显。Northern印迹分析表明，溶组织内阿米巴穿孔素和溶组织内阿米巴溶菌酶编码基因的表达在阿米巴与细菌共培养时没有显著变化，这表明在这些原始吞噬细胞中，抗菌武器库是组成性表达而非诱导表达。
