Staphylococcus aureus δ-toxin in aqueous solution: Behavior in monomeric and multimeric states

• Published in: Biophysical chemistry Vol. 227; pp. 21 - 28
• Main Authors: Melo, Maria Carolina de Araujo, Rodrigues, Cláudio Gabriel, Pol-Fachin, Laercio
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-08-2017
• Subjects: Bacterial Toxins - chemistry; Hemolytic; Membrane; Methanol; Molecular Docking Simulation; Molecular Dynamics Simulation; Peptide; Protein Multimerization; Protein Structure, Secondary; Solutions; Staphylococcus aureus - chemistry; Tetramers; Water; α-Helix; Membrane; α-Helix; Hemolytic; Tetramers; Peptide; Methanol
• ISSN: 0301-4622; 1873-4200
• DOI: 10.1016/j.bpc.2017.05.015

δ-Toxin is a 26 amino acid peptide capable of lysing several mammalian cell types and subcellular structures. Structurally, δ-toxin predominantly exhibits a α-helical secondary structure in membranes but, in aqueous solution, it adopts varying helical content. As no atomic-level data is available for this peptide in aqueous solutions and for the water-to-membrane transition, this work aims to characterize δ-toxin behavior in these conditions through molecular dynamics simulations in triplicates employing four different parameter sets. Our results, validated on previous experimental data, suggest that the peptide has from 4 to 16 residues folded as α-helix in aqueous solution, and a water-to-membrane foldamer comprising residues 14–18. Considering a previously proposed stable tetramer form in aqueous solutions, protein-protein docking and molecular dynamics studies were performed, suggesting that δ-toxin increases its α-helical content in such organization. The obtained results are expected to contribute in future studies on δ-toxin aggregation and interaction to biomembranes.
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•δ-Toxin has from around 4 to 16 residues folded as α-helix in aqueous solution.•δ-Toxin water-to-membrane foldamer is the region comprising residues 14–18.•δ-Toxin increases its α-helical content in its tetrameric organization.