Histones and DNA compete for binding polyphosphoinositides in bilayers

Area of Science:

• Cell Biology
• Biochemistry
• Lipid Bilayer Studies

Background:

• Phosphoinositides are increasingly found in the eukaryotic cell nucleus.
• Their interactions with nuclear components like histones are not well understood.

Purpose of the Study:

• To investigate the interaction between histones and phosphoinositides using model membranes.
• To understand the role of DNA in modulating these interactions.

Main Methods:

• Turbidimetric studies to observe vesicle aggregation.
• Confocal microscopy to visualize histone binding and aggregation.
• Isothermal titration calorimetry to quantify binding affinities.

Main Results:

• Histones dose-dependently aggregated liposomes containing negatively charged phospholipids, with phosphatidylinositol-4-phosphate (PIP) being more potent than phosphatidylinositol (PI).
• DNA addition prevented histone-induced vesicle aggregation and could disassemble existing aggregates.
• Calorimetry showed a higher association constant for PIP-histone interactions compared to PI-histone interactions.

Conclusions:

• Histones interact with phosphoinositides in model membranes, with DNA modulating these interactions.
• These findings suggest a complex interplay of histones, DNA, and phosphoinositides in nuclear processes.
• The study provides a foundational model for understanding nuclear lipid-protein interactions.