Refinement of OprH-LPS Interactions by Molecular Simulations

Area of Science:

• Bacterial outer membrane biophysics
• Molecular dynamics simulations
• Gram-negative bacterial cell envelope

Background:

• Gram-negative bacteria possess a unique outer membrane (OM) with lipopolysaccharide (LPS) in the outer leaflet.
• The Pseudomonas aeruginosa outer membrane protein H (OprH) stabilizes the OM by interacting with LPS.

Purpose of the Study:

• To investigate the influence of different LPS environments from P. aeruginosa and Escherichia coli on OM physical properties and OprH.
• To understand the molecular mechanisms behind OprH-LPS interactions and OM stability.

Main Methods:

• All-atom molecular dynamics simulations were employed.
• Simulations analyzed the structural and dynamic properties of OMs and OprH in various LPS contexts.

Main Results:

• P. aeruginosa OMs are thinner than E. coli OMs, but OprH dynamically adjusts its hydrophobic match, minimizing perceived differences.
• The presence of O-antigen significantly reduces OprH loop flexibility and enhances OprH-LPS interactions.
• OprH-LPS interactions are primarily dictated by OprH secondary structure and LPS chemical structure.

Conclusions:

• OprH exhibits adaptability to diverse LPS environments, crucial for maintaining outer membrane integrity.
• The O-antigen plays a key role in modulating OprH dynamics and interactions within the outer membrane.