Sticholysin II (StII) is a pore-forming actinoporin from the sea anemone Stichodactyla helianthus. A mechanistic model of its action has been proposed: proteins bind to cell membrane, insert their N-termini into the lipid core and assemble into homo-tetramer pores responsible for host-cell death. Because very likely the first 10 residues of StII N-terminus are critical for membrane penetration, to dissect the molecular details of that functionality, we studied two synthetic peptides: StII1-30 and StII16-35 . They show diverse haemolytic and candidacidal activity that correlate with distinct orientations in SDS micelles. NMR shows that StII1-30 partly inserts into the micelle, while StII16-35 lays on the micelle surface. These results justify the diverse concentration dependence of their candidacidal activity supposing a different mechanism of action and providing new hints on StII lytic activity at molecular level. Biotechnological application of these peptides, focused on the development of therapeutic immunocomplexes, may be envisaged.

中文翻译：

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对 Sticholysin II 衍生肽的构效关系的见解。


Sticholysin II (StII) 是一种来自海葵 Stichodactyla helianthus 的成孔放线菌素。其作用机制模型已被提出：蛋白质与细胞膜结合，将其 N 末端插入脂质核心，并组装成同源四聚体孔，导致宿主细胞死亡。由于 StII N 末端的前 10 个残基很可能对于膜渗透至关重要，为了剖析该功能的分子细节，我们研究了两种合成肽：StII1-30 和 StII16-35。它们表现出不同的溶血和念珠菌活性，与 SDS 胶束中的不同方向相关。 NMR显示StII1-30部分插入胶束中，而StII16-35则位于胶束表面。这些结果证明了其候选活性的不同浓度依赖性，假设不同的作用机制，并为分子水平上的 StII 裂解活性提供新的提示。可以设想这些肽的生物技术应用，重点是治疗性免疫复合物的开发。