High-speed atomic force microscopy highlights new molecular mechanism of daptomycin action

Area of Science:

• Microscopy and Biophysics
• Molecular Biology
• Pharmacology

Background:

• Antimicrobial peptides are crucial for fighting infections.
• Daptomycin is a medically prescribed lipopeptide antibiotic with a poorly understood mechanism of action.
• Understanding Daptomycin's molecular interactions is vital for combating antibiotic resistance.

Purpose of the Study:

• To visualize the molecular-level activity of Daptomycin on bacterial membranes using high-speed atomic force microscopy (HS-AFM).
• To investigate Daptomycin's behavior under infection-like conditions.
• To elucidate novel molecular mechanisms of Daptomycin action and resistance.

Main Methods:

• High-speed atomic force microscopy (HS-AFM) for molecular visualization.
• Simulated infection-like conditions (temperature, lipid composition, antibiotic concentration).
• Multi-scale correlation using electron microscopy, optical microscopy, and the lipid tension probe FliptR.

Main Results:

• Confirmed Daptomycin oligomerization and the formation of half pores.
• Discovered new mechanisms for toroidal pore formation and Daptomycin resistance.
• Quantified the energy profile of interacting Daptomycin oligomers.
• Correlated molecular findings with cellular responses in Bacillus subtilis, showing healthier cell walls lead to smaller membrane deformations.

Conclusions:

• HS-AFM provides unprecedented molecular-level insights into Daptomycin's membrane activity.
• Daptomycin employs complex mechanisms involving oligomerization and pore formation.
• Cellular health influences membrane response to Daptomycin, impacting antibiotic efficacy.