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

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• δ-Toxin is a 26-amino acid peptide known to lyse mammalian cells and subcellular structures.
• Its structure varies between aqueous solutions (varying helical content) and membranes (predominantly α-helical).
• Atomic-level structural data for aqueous solutions and the water-to-membrane transition are lacking.

Purpose of the Study:

• To characterize the behavior and structure of δ-toxin in aqueous solutions.
• To elucidate the structural changes during the water-to-membrane transition.
• To investigate the structural impact of tetramer formation in aqueous solution.

Main Methods:

• Molecular dynamics (MD) simulations were performed in triplicates using four distinct parameter sets.
• Protein-protein docking was employed to study the tetramer formation.
• MD simulations were used to analyze the structural dynamics of the tetramer.

Main Results:

• In aqueous solution, δ-toxin exhibits α-helical content ranging from 4 to 16 residues.
• A water-to-membrane foldamer involving residues 14-18 was identified.
• In a proposed tetramer formation, δ-toxin shows an increased α-helical content.

Conclusions:

• The study provides atomic-level insights into δ-toxin's structure in solution and its transition to membranes.
• Findings validate previous experimental data and offer a structural basis for further research.
• Results are expected to aid future investigations into δ-toxin aggregation and biomembrane interactions.