Structures and Dynamics of Anionic Lipoprotein Nanodiscs.

Area of Science:

• Biophysics
• Structural Biology
• Materials Science

Background:

• Nanolipoprotein discs (NDs) are crucial for membrane protein studies.
• Lipid composition's effect on ND structure and dynamics is poorly understood.

Purpose of the Study:

• Investigate how adding anionic POPG to POPC NDs affects ND structure and dynamics.
• Determine the impact of increasing POPG concentration on ND shape, lipid core, and MSP1D1 protein dynamics.

Main Methods:

• Small-angle X-ray and neutron scattering (SAXS and SANS) on variable-composition NDs.
• Molecular dynamics (MD) simulations to analyze ND structure and protein behavior.
• Global fitting to stacked elliptical cylinder and curvature-accounting models.

Main Results:

• Increasing POPG leads to more elliptical NDs.
• POPG incorporation suppresses aggregation and stabilizes the MSP1D1 protein.
• MD simulations confirm POPG's role in suppressing N-terminal helix disengagement.

Conclusions:

• Anionic lipids like POPG induce significant structural changes in NDs.
• POPG enhances ND stability and reduces protein conformational heterogeneity.
• Findings inform future studies of membrane proteins in mixed-composition NDs.