Revisiting the interaction between the chaperone Skp and lipopolysaccharide

Area of Science:

• Microbiology and Molecular Biology
• Bacterial Outer Membrane Structure and Function

Background:

• The bacterial outer membrane contains lipids and proteins essential for cell viability.
• Lipopolysaccharide (LPS) and outer membrane proteins (Omps) are transported via specific systems.
• Periplasmic chaperones, such as Skp, are involved in outer membrane protein transport.

Purpose of the Study:

• To investigate the specificity of the interaction between the periplasmic chaperone Skp and lipopolysaccharide (LPS).
• To determine the biological relevance of Skp-LPS interactions in bacterial outer membrane biogenesis.

Main Methods:

• High-resolution Nuclear Magnetic Resonance (NMR) spectroscopy to study Skp-LPS interactions.
• Bioinformatic analysis of amino acid conservation in LPS-binding proteins.
• Molecular Dynamics (MD) simulations to analyze binding sites and interactions.

Main Results:

• NMR data revealed nonspecific interaction between LPS and Skp, causing Skp trimer destabilization.
• This nonspecific interaction resembles denaturation induced by detergents like LDAO.
• Bioinformatic and structural analyses confirmed the absence of a specific LPS binding site on Skp.

Conclusions:

• The interaction between Skp and LPS is nonspecific and lacks apparent biological relevance for LPS transport.
• A conserved salt-bridge network within Skp was identified, likely crucial for its primary chaperone function.
• These findings necessitate a re-evaluation of the proposed roles of Skp in LPS trafficking.