Protein-induced membrane asymmetry modulates OMP folding kinetics and stability

Area of Science:

• Membrane biophysics
• Protein folding dynamics
• Biomolecular engineering

Background:

• Biological membranes exhibit asymmetry due to lipid and small molecule distribution.
• Membrane asymmetry influences macromolecular behavior, but is poorly understood.
• Existing in vitro systems struggle to replicate complex natural membrane asymmetry.

Purpose of the Study:

• To develop a method for creating asymmetric proteoliposomes with controlled protein-induced dipoles.
• To investigate how protein sequence and membrane dipole affect folding kinetics and stability.
• To explore the potential of manipulating membrane environments for cellular adaptation.

Main Methods:

• Utilizing the unidirectional folding of the outer membrane protein A (OmpA).
• Engineering OmpA loop sequences to create specific protein-induced dipoles.
• Characterizing folding kinetics and stability of OmpA variants in asymmetric proteoliposomes.

Main Results:

• Both OmpA primary sequence and membrane dipole significantly modulate folding rates.
• Complementary matching of protein charge to membrane dipole enhances folding kinetics.
• Enhanced folding kinetics and stability were observed when protein charge and membrane dipole were aligned.

Conclusions:

• OmpA folding into asymmetric proteoliposomes provides a model for studying membrane asymmetry.
• Protein sequence and membrane dipole interactions are critical for protein folding and stability.
• Cells may utilize charge-based mechanisms in membrane proteins to adapt and survive by modulating membrane environments.