Fast Collisional Lipid Transfer Among Polymer-Bounded Nanodiscs

Some styrene/maleic acid (SMA) copolymers solubilise membrane lipids and proteins to form polymer-bounded nanodiscs termed SMA/lipid particles (SMALPs). Although SMALPs preserve a lipid-bilayer core, they appear to be more dynamic than other membrane mimics. We used time-resolved Förster resonance e...

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Bibliographic Details
Published in:Scientific reports 2017-04, Vol.7 (1), p.45875-45875, Article 45875
Main Authors: Cuevas Arenas, Rodrigo, Danielczak, Bartholomäus, Martel, Anne, Porcar, Lionel, Breyton, Cécile, Ebel, Christine, Keller, Sandro
Format: Article
Language:English
Subjects:
631/57/2282
639/638/440/950
639/638/455/960
639/925/357/354
Biochemistry, Molecular Biology
Copolymers
Energy transfer
Enthalpy
Humanities and Social Sciences
Hydrophobicity
Kinetics
Life Sciences
Lipids
Maleic acid
multidisciplinary
Neutron scattering
Phospholipids
Polymers
Science
Structural Biology
Styrene
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Summary:Some styrene/maleic acid (SMA) copolymers solubilise membrane lipids and proteins to form polymer-bounded nanodiscs termed SMA/lipid particles (SMALPs). Although SMALPs preserve a lipid-bilayer core, they appear to be more dynamic than other membrane mimics. We used time-resolved Förster resonance energy transfer and small-angle neutron scattering to determine the kinetics and the mechanisms of phospholipid transfer among SMALPs. In contrast with vesicles or protein-bounded nanodiscs, SMALPs exchange lipids not only by monomer diffusion but also by fast collisional transfer. Under typical experimental conditions, lipid exchange occurs within seconds in the case of SMALPs but takes minutes to days in the other bilayer particles. The diffusional and second-order collisional exchange rate constants for SMALPs at 30 °C are k dif  = 0.287 s −1 and k col  = 222 M −1 s −1 , respectively. Together with the fast kinetics, the observed invariability of the rate constants with probe hydrophobicity and the moderate activation enthalpy of ~70 kJ mol −1 imply that lipids exchange through a “hydrocarbon continuum” enabled by the flexible nature of the SMA belt surrounding the lipid-bilayer core. Owing to their fast lipid-exchange kinetics, SMALPs represent highly dynamic equilibrium rather than kinetically trapped membrane mimics, which has important implications for studying protein/lipid interactions in polymer-bounded nanodiscs.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep45875