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Fast Collisional Lipid Transfer Among Polymer-Bounded Nanodiscs
Rodrigo Cuevas Arenas1, Bartholomäus Danielczak1, Anne Martel2
1Molecular Biophysics, University of Kaiserslautern, Erwin-Schrödinger-Str. 13, 67663 Kaiserslautern, Germany.
Scientific Reports
|April 6, 2017
Summary
Styrene/maleic acid (SMA) copolymers form nanodiscs (SMALPs) that rapidly exchange lipids via diffusion and collisions. This dynamic nature makes SMALPs ideal for studying protein-lipid interactions.
Area of Science:
- Biophysics
- Polymer Science
- Membrane Biophysics
Background:
- Styrene/maleic acid (SMA) copolymers form polymer-bounded nanodiscs (SMALPs) that mimic cell membranes.
- SMALPs are known for their dynamic properties compared to other membrane mimetics.
Purpose of the Study:
- To investigate the kinetics and mechanisms of phospholipid transfer among SMALPs.
- To compare lipid exchange dynamics in SMALPs with other membrane mimics like vesicles and protein-bounded nanodiscs.
Main Methods:
- Time-resolved Förster resonance energy transfer (TR-FRET).
- Small-angle neutron scattering (SANS).
Main Results:
- SMALPs exhibit rapid lipid exchange through both monomer diffusion and fast collisional transfer.
- Lipid exchange in SMALPs occurs within seconds, significantly faster than minutes to days for vesicles or protein nanodiscs.
- Rate constants are independent of probe hydrophobicity, suggesting exchange via a hydrocarbon continuum facilitated by the flexible SMA belt.
Conclusions:
- SMALPs are highly dynamic equilibrium systems, not kinetically trapped mimics, due to their fast lipid exchange kinetics.
- The flexible SMA belt enables a "hydrocarbon continuum" for efficient lipid transfer.
- These findings have significant implications for using SMALPs to study protein/lipid interactions.