Binding-induced lipid domains: Peptide-membrane interactions with PIP₂ and PS

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Cell signaling involves intricate lipid-protein interactions critical for biological functions.
• The myristoylated alanine-rich C-kinase substrate (MARCKS) is a key regulator, with its effector domain (ED) anchoring to plasma membranes.
• MARCKS-ED induces domain formation in membranes containing phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylserine (PS), but binding mechanisms are unclear.

Purpose of the Study:

• To investigate the composition-dependent affinity of MARCKS-ED binding to lipid membranes.
• To elucidate MARCKS-ED-induced changes in interfacial environments using advanced spectroscopic techniques.
• To understand the molecular mechanisms governing MARCKS-ED interactions with specific membrane lipids like PIP2 and PS.

Main Methods:

• Utilized two-dimensional infrared spectroscopy to probe interfacial environments.
• Employed fluorescence anisotropy to assess lipid-protein binding dynamics.
• Investigated binding affinities and interfacial changes in lipid vesicles with varied compositions.

Main Results:

• Both phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylserine (PS) facilitate MARCKS-ED binding to lipid vesicles.
• Interfacial water dynamics exhibit divergent patterns based on lipid composition due to specific lipid-peptide interactions.
• MARCKS-ED binding leads to PIP2 sequestration, while PS distribution remains unchanged; PIP2 and PS colocalize into domains regardless of peptide presence.

Conclusions:

• Membrane lipid composition significantly influences MARCKS-ED binding affinity and interfacial environment.
• MARCKS-ED binding induces specific lipid sequestration and domain formation, impacting cell signaling pathways.
• This research provides molecular insights into lipid-protein interactions at the membrane interface.