Spin-label EPR on alpha-synuclein reveals differences in the membrane binding affinity of the two antiparallel helices.
The putative function of the Parkinson's disease-related protein alpha-Synuclein (alphaS) is thought to involve membrane binding. Therefore, the interaction of alphaS with membranes composed of zwitterionic (POPC) and anionic (POPG) lipids was investigated through the mobility of spin labels attached to the protein. Differently labelled variants of alphaS were produced, containing a spin label at positions 9, 18 (both helix 1), 69, 90 (both helix 2), and 140 (C terminus). Protein binding to POPC/POPG vesicles for all but alphaS140 resulted in two mobility components with correlation times of 0.5 and 3 ns, for POPG mole fractions >0.4. Monitoring these components as a function of the POPG mole fraction revealed that at low negative-charge densities helix 1 is more tightly bound than helix 2; this indicates a partially bound form of alphaS. Thus, the interaction of alphaS with membranes of low charge densities might be initiated at helix 1. The local binding information thus obtained gives a more differentiated picture of the affinity of alphaS to membranes. These findings contribute to our understanding of the details and structural consequences of alphaS-membrane interactions.
Drescher
Malte
M
Department of Molecular Physics, Leiden University, 2300 RA Leiden, The Netherlands.
Godschalk
Frans
F
Veldhuis
Gertjan
G
van Rooijen
Bart D
BD
Subramaniam
Vinod
V
Huber
Martina
M
D000595:Amino Acid Sequence; D003198:Computer Simulation; D004578:Electron Spin Resonance Spectroscopy; D008567:Membranes, Artificial; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013113:Spin Labels; D013499:Surface Properties; D051844:alpha-Synuclein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D008567:Membranes, Artificial; D013113:Spin Labels; D051844:alpha-Synuclein