Differential interaction of α-synuclein N-terminal segment with mitochondrial model membranes

Alpha-synuclein (α-syn) is an intrinsically-disordered protein that has been associated with Parkinson's disease through its deposition in an amyloid fibril form within Lewy Body. Several lines of evidence suggest that the physical association of α-syn with the mitochondrial membranes may cause membrane damage and mitochondrial dysfunction, playing an important role in disease progression. Although there is strong evidence that the N-terminus part of α-syn is essential for membrane affinity, cooperative formation of helical domains and regulation of mitochondria membrane permeability, the amino acids involve in this membrane binding is still controversial. Fluorescence spectroscopy, circular dichroism and Langmuir monolayer technique were used to elucidate this recognition process of mitochondrial membrane system by synthetic peptides derived from α-syn N-terminal segment. The results obtained in this work show that the first 15 amino acid of the α-syn N-terminal segment mainly participate in the anchoring, perturbing the membrane hydrophobic region, while the peptide corresponding to 16-30 residues interacts only with the phospholipid polar headgroup, confirming that the binding affinity of the N-terminus is nonuniform.