Mixed liposomes containing gram-positive bacteria lipids: Lipoteichoic acid (LTA) induced structural changes

Area of Science:

• Biophysics
• Membrane Biology
• Materials Science

Background:

• Lipoteichoic acid (LTA) is a crucial component of Gram-positive bacterial membranes.
• The precise role of LTA compositional variations in membrane structural integrity remains unclear.
• Understanding LTA's influence is key to deciphering bacterial membrane function.

Purpose of the Study:

• To investigate structural alterations in mixed liposomes mimicking Gram-positive bacterial membranes.
• To determine how varying Bacillus Subtilis LTA concentrations affect membrane structure and stability.
• To elucidate the impact of temperature on LTA-modulated membrane properties.

Main Methods:

• Utilized mixed liposomes with controlled Bacillus Subtilis LTA concentrations (0-15 mol%).
• Employed Small-Angle Neutron Scattering (SANS) to analyze structural changes.
• Applied Dynamic Light Scattering (DLS) and Cryo-Transmission Electron Microscopy (Cryo-TEM) for vesicle characterization.

Main Results:

• Formation of mixed unilamellar vesicles stabilized by LTA polyphosphates was observed.
• Vesicle size increased with LTA concentration up to ~6.5 mol%, followed by a decrease.
• Higher temperatures (80°C) resulted in larger vesicles with thinner shells and aggregate formation at high LTA concentrations.

Conclusions:

• LTA concentration significantly modulates the structural organization and size of model bacterial membranes.
• Steric and electrostatic interactions of LTA, along with chain fluidity, dictate membrane packing and stability.
• Findings provide insights into LTA's role in maintaining bacterial membrane integrity under varying conditions.