Alpha-synuclein structures from fluorescence energy-transfer kinetics: implications for the role of the protein in Parkinson's disease.
Parkinson's disease is associated with the deposition and accumulation of alpha-synuclein fibrils in the brain. A30P and A53T mutations have been linked to the early-onset familial disease state. Time-resolved tryptophan fluorescence energy-transfer measurements have been used to probe the structures of pseudo-wild-type and mutant (A30P) alpha-synucleins at physiological pH (7.4), in acidic pH (4.4) solutions, and in the presence of SDS micelles, a membrane mimic. Fluorescent donor-energy acceptor (DA) distance distributions for six different tryptophan/3-nitro-tyrosine pairs reveal the presence of compact, intermediate, and extended conformations of the protein. CD spectra indicate that the protein develops substantial helical structure in the presence of SDS micelles. DA distributions show that micelles induce compaction in the N-terminal region and expansion of the acidic C terminus. In acidic solutions, there is an increased population of collapsed structures in the C-terminal region. Energy-transfer measurements demonstrate that the average DA distances for the W4-Y19 and Y19-W39 pairs are longer in one of the two disease-related mutants (A30P).
Lee
Jennifer C
JC
Beckman Institute, California Institute of Technology, Pasadena, CA 91125-7400, USA. lee@caltech.edu
Langen
Ralf
R
Hummel
Patrick A
PA
Gray
Harry B
HB
Winkler
Jay R
JR
D000595:Amino Acid Sequence; D055592:Biophysical Phenomena; D001703:Biophysics; D002942:Circular Dichroism; D005454:Fluorescence Polarization; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008823:Micelles; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D010300:Parkinson Disease / Q000209:etiology*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012996:Solutions; D051843:Synucleins; D051844:alpha-Synuclein
D008823:Micelles; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; C497604:SNCA protein, human; D012996:Solutions; D051843:Synucleins; D051844:alpha-Synuclein