Membrane binding of zebrafish actinoporin-like protein: AF domains, a novel superfamily of cell membrane binding domains

• Published in: Biochemical journal Vol. 398; no. 3; pp. 381 - 392
• Main Authors: Gutiérrez-Aguirre, Ion, Trontelj, Peter, Macek, Peter, Lakey, Jeremy H, Anderluh, Gregor
• Format: Journal Article
• Language: English
• Published: England Portland Press 15.09.2006; Portland Press Ltd
• Subjects: Amino Acid Sequence; Animals; Cell Membrane - metabolism; Danio rerio; Escherichia coli; Freshwater; Fungi - metabolism; Lectins - metabolism; Membrane Proteins - chemistry; Membrane Proteins - metabolism; Models, Molecular; Molecular Sequence Data; Phylogeny; Porins - chemistry; Porins - genetics; Porins - metabolism; Protein Binding; Protein Conformation; Protein Structure, Tertiary; Zebrafish; Zebrafish Proteins - chemistry; Zebrafish Proteins - metabolism; Life Sciences
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj20060206

Actinoporins are potent eukaryotic pore-forming toxins specific for sphingomyelin-containing membranes. They are structurally similar to members of the fungal fruit-body lectin family that bind cell-surface exposed Thomsen-Friedenreich antigen. In the present study we found a number of sequences in public databases with similarity to actinoporins. They originate from three animal and two plant phyla and can be classified in three families according to phylogenetic analysis. The sequence similarity is confined to a region from the C-terminal half of the actinoporin molecule and comprises the membrane binding site with a highly conserved P-[WYF]-D pattern. A member of this novel actinoporin-like protein family from zebrafish was cloned and expressed in Escherichia coli. It displays membrane-binding behaviour but does not have permeabilizing activity or sphingomyelin specificity, two properties typical of actinoporins. We propose that the three families of actinoporin-like proteins and the fungal fruit-body lectin family comprise a novel superfamily of membrane binding proteins, tentatively called AF domains (abbreviated from actinoporin-like proteins and fungal fruit-body lectins).