Antiparallel Arrangement of the Helices of Vesicle-Bound α-Synuclein

Drescher, Malte; Veldhuis, Gertjan; Rooijen, Bart D. van; Milikisyants, Sergey; Subramaniam, Vinod; Huber, Martina

doi:10.1021/ja801594s

Cited by 110 publications

(128 citation statements)

References 30 publications

Supporting

Mentioning

118

Contrasting

Unclassified

Order By: Relevance

“…However, the conformation of AS on lipid membranes is still a subject of discussion. Some EPR reports suggest a broken-helix conformation (40,41) similar to that of the micelle-bound protein (42), whereas others show an extended ␣-helix for residues 9 -90 (43,44), a finding that is also supported by single molecule FRET measurements (45,46).…”

mentioning

confidence: 86%

Specificity and Kinetics of α-Synuclein Binding to Model Membranes Determined with Fluorescent Excited State Intramolecular Proton Transfer (ESIPT) Probe

Shvadchak¹,

Falomir-Lockhart²,

Yushchenko³

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

Parkinson disease is characterized cytopathologically by the deposition in the midbrain of aggregates composed primarily of the presynaptic neuronal protein ␣-synuclein (AS). Neurotoxicity is currently attributed to oligomeric microaggregates subjected to oxidative modification and promoting mitochondrial and proteasomal dysfunction. Unphysiological binding to membranes of these and other organelles is presumably involved. In this study, we performed a systematic determination of the influence of charge, phase, curvature, defects, and lipid unsaturation on AS binding to model membranes using a new sensitive solvatochromic fluorescent probe. The interaction of AS with vesicular membranes is fast and reversible. The protein dissociates from neutral membranes upon thermal transition to the liquid disordered phase and transfers to vesicles with higher affinity. The binding of AS to neutral and negatively charged membranes occurs by apparently different mechanisms. Interaction with neutral bilayers requires the presence of membrane defects; binding increases with membrane curvature and rigidity and decreases in the presence of cholesterol. The association with negatively charged membranes is much stronger and much less sensitive to membrane curvature, phase, and cholesterol content. The presence of unsaturated lipids increases binding in all cases. These findings provide insight into the relation between membrane physical properties and AS binding affinity and dynamics that presumably define protein localization in vivo and, thereby, the role of AS in the physiopathology of Parkinson disease.

show abstract

mentioning

confidence: 86%

Specificity and Kinetics of α-Synuclein Binding to Model Membranes Determined with Fluorescent Excited State Intramolecular Proton Transfer (ESIPT) Probe

Shvadchak¹,

Falomir-Lockhart²,

Yushchenko³

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…1A) (20,21,26). EPR analyses of ␣-synuclein derivatives bound to small unilamellar lipid vesicles (SUVs) have provided evidence for an elongated helical structure devoid of significant tertiary packing (28), or suggested a broken helical structure more recently (29,30). To relate these reported micelle-and vesicle-bound experimentally-observed structures, we previously carried out a detailed ensemble thermodynamic characterization of the SDS-induced folding of ␣-synuclein in broad ranges of SDS concentration, temperature, and pH, using CD spectroscopy, providing evidence for an inherently multistate ␣-synuclein folding (22).…”

mentioning

confidence: 99%

“…Several ensemble biophysical methods including NMR (20,21,26,27), EPR (28)(29)(30), CD (21,22,31,32) and fluorescence spectroscopy (33,34) have provided valuable insights into the structural features of disordered and folded ␣-synuclein. In the context of membrane-binding, solution NMR studies performed in the presence of SDS spherical micelles demonstrated that micelle-bound ␣-synuclein adopts a broken ␣-helix structure, which consists of a pair of curved antiparallel helices connected by a well-ordered extended linker, and followed by a short extended region and a predominantly unstructured mobile tail (Fig.…”

mentioning

confidence: 99%

Interplay of α-synuclein binding and conformational switching probed by single-molecule fluorescence

Ferreon

Gambin²,

Lemke³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

379

449

View full text Add to dashboard Cite

We studied the coupled binding and folding of ␣-synuclein, an intrinsically disordered protein linked with Parkinson's disease. Using single-molecule fluorescence resonance energy transfer and correlation methods, we directly probed protein membrane association, structural distributions, and dynamics. Results revealed an intricate energy landscape on which binding of ␣-synuclein to amphiphilic small molecules or membrane-like partners modulates conformational transitions between a natively unfolded state and multiple ␣-helical structures. ␣-Synuclein conformation is not continuously tunable, but instead partitions into 2 main classes of folding landscape structural minima. The switch between a broken and an extended helical structure can be triggered by changing the concentration of binding partners or by varying the curvature of the binding surfaces presented by micelles or bilayers composed of the lipid-mimetic SDS. Single-molecule experiments with lipid vesicles of various composition showed that a low fraction of negatively charged lipids, similar to that found in biological membranes, was sufficient to drive ␣-synuclein binding and folding, resulting here in the induction of an extended helical structure. Overall, our results imply that the 2 folded structures are preencoded by the ␣-synuclein amino acid sequence, and are tunable by small-molecule supramolecular states and differing membrane properties, suggesting novel control elements for biological and amyloid regulation of ␣-synuclein.A lpha-synuclein, a highly acidic 140-residue protein expressed at high levels in the human brain and enriched in presynaptic nerve termini, is a member of the growing class of intrinsically disordered proteins that adopt ordered structure upon interaction with cellular partners (1-5). This natively unfolded protein plays crucial roles in the pathogenesis of several neurodegenerative disorders including Parkinson's disease and Alzheimer's disease (6-9). Although several physiological functions have been proposed for the protein, including roles in the regulation of distinct pools of presynaptic vesicles (10, 11), maintenance of SNARE protein complexes (12), modulation of neural plasticity (13), control of dopamine neurotransmission (14), and ER-Golgi trafficking (15), its precise biological role remains unclear. Nevertheless, membrane interaction is generally believed to be a key modulator of ␣-synuclein function (16,17).Sequence analysis predicts ␣-synuclein interaction with lipid membranes through amphipathic ␣-helices encoded by 7 imperfect 11-residue repeats, approximately 4 of which are located in the highly basic N-terminal region of the protein, and 3 in the highly acidic and hydrophobic NAC region (non-A␤ component of Alzheimer's disease amyloid) (13, 18). Not surprisingly, the protein undergoes structural transitions upon binding to either brain-derived or synthetic acidic phospholipid vesicles, adopting ␣-helical conformations in the membrane-bound form (17)(18)(19). Similarly, ␣-synuclein assumes helical structu...

show abstract

“…Nevertheless, studies using smaller diameter spheroidal micelles, but also certain vesicle preparations (e.g. containing exclusively 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1Ј-rac-glycerol) (POPG) lipids), showed that the elongated helix can be broken, resulting in an antiparallel arrangement of two helices (21)(22)(23)(24)(25)(26)(27) or a mixture of elongated and broken helices (28). In addition, a distinct helix break can be avoided even on a micelle by rearranging the amphiphilic amino acid sequence (29).…”

mentioning

confidence: 99%

“…S5). This SUV type will bias ␣S toward antiparallel conformations (26), but because both ␣S(Cys 11 -Cys 81 ) and ␣S(Cys…”

mentioning

confidence: 99%

α-Synuclein Populates Both Elongated and Broken Helix States on Small Unilamellar Vesicles

Lokappa

Ulmer

2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

The misfolding of the protein ␣-synuclein (␣S) has been implicated in the molecular chain of events leading to Parkinson disease. Physiologically, ␣S undergoes a transition from a random coil to helical conformation upon encountering synaptic vesicle membranes. On analogous small unilamellar vesicles (SUVs), the conformation of ␣S is dominated by a single elongated ␣S helix. However, alternative broken helix states have been postulated, mandating experimental clarification. Here, the upper limit for the free energy difference between elongated and broken helix conformations on SUVs resembling synaptic vesicles was determined to be 1.2 ؎ 0.4 kcal/mol, which amounts to a population ratio of 7.6:1 between both states (12% broken helices). In response to helix breaks at different positions, ␣S rearranged in an opportunistic manner, thereby minimizing helix abrogations to as little as one to two turns. Enthalpy and entropy measurements of gel state SUV-␣S interactions indicated that broken helix states retain the ability to relieve membrane-packing stress. Thus, broken helix states are a distinct physiological feature of the vesicle-bound ␣S state, making it a "checkered" protein of multiple parallel conformations. A continuous interconversion between structural states may contribute to pathological ␣S misfolding. The protein ␣-synuclein (␣S)2 was discovered in amyloid plaques and as a gene whose expression is altered during the period of song learning in the zebra finch (1, 2), well representing subsequent discoveries regarding the pathological and physiological nature of this protein. In humans, each of the point mutations A30P, E46K, and A53T, as well as gene triplication, gives rise to familial parkinsonism and dementia (3-6). In conjunction with the propensity of ␣S to misfold into amyloid fibrils in vitro and in vivo (7,8), this places ␣S at the center of molecular events leading to prevalent human neurodegenerative disorders such as Parkinson disease (9). Physiologically, ␣S is a presynaptic brain protein that co-localizes with synaptic vesicles (10, 11). The binding and concomitant stabilization of such vesicles may modulate the threshold of neurotransmitter release, i.e. neural plasticity (1, 12, 13). In addition, ␣S can promote SNARE (soluble NSF attachment protein receptor) complex assembly (14).In aqueous solution, ␣S is highly soluble yet lacks secondary structure (15). It may therefore be considered to be an intrinsically unfolded protein. Based on the repetitive amphiphilic amino acid sequence of its N-terminal 89 residues (see Fig. 1A), it was early on proposed and verified that ␣S adopts predominantly helical conformation upon associating with small unilamellar vesicles (SUVs) (1, 16). Recently, the average structure of ␣S when bound to SUVs composed of 1-palmitoyl-2-oleoyl-snglycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-snglycero-3-phospho-L-serine (POPS) lipids was reported (17). This structure, which was based on EPR distance and membrane immersion measurements, assigned an uninterrupted el...

show abstract

Antiparallel Arrangement of the Helices of Vesicle-Bound α-Synuclein

Cited by 110 publications

References 30 publications

Specificity and Kinetics of α-Synuclein Binding to Model Membranes Determined with Fluorescent Excited State Intramolecular Proton Transfer (ESIPT) Probe

Specificity and Kinetics of α-Synuclein Binding to Model Membranes Determined with Fluorescent Excited State Intramolecular Proton Transfer (ESIPT) Probe

Interplay of α-synuclein binding and conformational switching probed by single-molecule fluorescence

α-Synuclein Populates Both Elongated and Broken Helix States on Small Unilamellar Vesicles

Contact Info

Product

Resources

About