Spin-label EPR of alpha-Synuclein on Vesicles Reveals Antiparallel Arrangement and Differences in the Membrane Binding Affinity of the two Helices
2009; Elsevier BV; Volume: 96; Issue: 3 Linguagem: Inglês
10.1016/j.bpj.2008.12.920
ISSN1542-0086
AutoresMartina Huber, Malte Drescher, Frans Godschalk, Sergey Milikisyants, Gertjan Veldhuis, Bart van Rooijen, Vinod Subramaniam,
Tópico(s)Electron Spin Resonance Studies
ResumoThe Parkinson's disease-related protein α-Synuclein (αS) is a 140 residue protein that is natively unfolded in solution. Its membrane-binding properties are implied in its physiological or pathologic activity. αS was investigated by spin-label EPR. By Electron-Electron Double Resonance (DEER) the distance between the spinlabels in four double mutants was determined in the vesicle-bound and free form of αS, revealing antiparallel arrangement of the helices. Thus, even in the vesicle-bound form αS has the horseshoe conformation, revealing that this conformation is intrinsic to the protein, rather than induced by the small size of micelles investigated previously. Mobility analysis of five single spin-labeled mutants showed that the membrane affinity of helix 2, comprising residues 45 - 90, decreases with decreasing negative charge of the membrane surface, suggesting differential binding of αS to membranes. The findings reveal molecular details of the membrane-bound conformation of αS not previously obtained.
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