Daptomycin Strongly Affects the Phase Behavior of Model Lipid Bilayers.

Area of Science:

• Microbiology
• Biophysics
• Medicinal Chemistry

Background:

• Daptomycin (DAP) is a last-resort antibiotic for Gram-positive infections.
• Its mechanism involves bacterial membrane interaction, which is crucial for its efficacy.
• Understanding DAP's membrane targeting can help combat antibiotic resistance.

Purpose of the Study:

• To investigate the molecular mechanism of Daptomycin's interaction with bacterial membranes.
• To elucidate how Daptomycin affects the biophysical properties of lipid bilayers containing phosphatidylglycerol (PG).

Main Methods:

• Fluorescence microscopy
• Atomic Force Microscopy (AFM) with spectroscopy

Main Results:

• Daptomycin preferentially binds to phosphatidylglycerol (PG) headgroups in lipid bilayers.
• DAP penetrates deeper into the lipid bilayer where PG is present.
• DAP stiffens fluid-phase PG domains and fluidifies solid-phase PG domains.

Conclusions:

• Daptomycin's interaction with PG headgroups significantly impacts bacterial membrane thermodynamics.
• These findings provide insights into DAP's mechanism of action and potential for developing resistance-evading analogues.