Development of membrane-insertable lipid scrambling peptides: A time-resolved small-angle neutron scattering study

Area of Science:

• Biochemistry
• Membrane Biology
• Biophysics

Background:

• Phospholipid transbilayer movement (flip-flop) is crucial for cell homeostasis and intercellular interactions.
• Dysregulation of lipid asymmetry by phospholipid scramblases is implicated in apoptosis, coagulation, and viral infections.
• Artificial control of membrane flip-flop is of significant biological and medical interest.

Purpose of the Study:

• To develop novel transmembrane peptides capable of artificially inducing and controlling phospholipid flip-flop.
• To investigate the mechanism by which these peptides perturb the membrane and promote lipid scrambling.

Main Methods:

• Development of synthetic transmembrane peptides with varying amino acid compositions.
• Utilizing time-resolved small-angle neutron scattering (TR-SAXS) to monitor lipid flip-flop in vesicles.
• Characterization of peptide behavior within lipid bilayers.

Main Results:

• Peptides containing a central glutamine residue successfully induced phospholipid flip-flop in lipid vesicles.
• The presence of the glutamine residue was essential for scramblase activity; peptides lacking it had no effect.
• Glutamine-containing peptides demonstrated scramblase activity in their monomeric form, suggesting perturbation of the membrane hydrocarbon region.

Conclusions:

• Synthetic transmembrane peptides with a central glutamine residue can effectively promote lipid flip-flop.
• The mechanism involves the exposure of the polar glutamine residue to the hydrophobic membrane core, disrupting lipid packing.
• These glutamine-containing scrambling peptides represent valuable tools for regulating plasma membrane lipid dynamics.