The sticholysin family of pore-forming toxins induces the mixing of lipids in membrane domains

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• 作者：Uris Ros ; Michelle A. Edwards ; Raquel F. Ep ; Maria E. Lanio ; Shirley Schreier ; Christopher M. Yip ; Carlos Alvarez ; Richard M. Ep
• 关键词：StI and StII ; sticholysin I and II ; PFTs ; pore forming toxins ; SM ; Sphingomyelin ; EqtII ; equinatoxin II ; FraC ; fragaceatoxin C ; DSC ; Differential Scanning Calorimetry ; AFM ; Atomic Force Microscopy ; DMPC ; Dimyristoylphosphatidylcholine ; DPPC ; Dipalmitoylph
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：2013
• 出版时间：November, 2013
• 年：2013
• 卷：1828
• 期：11
• 页码：2757-2762
• 全文大小：599 K

文摘

Sticholysins (Sts) I and II (StI/II) are pore-forming toxins (PFTs) produced by the Caribbean Sea anemone Stichodactyla helianthus belonging to the actinoporin family, a unique class of eukaryotic PFTs exclusively found in sea anemones. The role of lipid phase co-existence in the mechanism of the action of membranolytic proteins and peptides is not clearly understood. As for actinoporins, it has been proposed that phase separation promotes pore forming activity. However little is known about the effect of sticholysins on the phase separation of lipids in membranes. To gain insight into the mechanism of action of sticholysins, we evaluated the effect of these proteins on lipid segregation using differential scanning calorimetry (DSC) and atomic force microscopy (AFM). New evidence was obtained reflecting that these proteins reduce line tension in the membrane by promoting lipid mixing. In terms of the relevance for the mechanism of action of actinoporins, we hypothesize that expanding lipid disordered phases into lipid ordered phases decreases the lipid packing at the borders of the lipid raft, turning it into a more suitable environment for N-terminal insertion and pore formation.