Structure of membrane-bound alpha-synuclein studied by site-directed spin labeling

Area of Science:

• Biochemistry
• Structural Biology
• Neuroscience

Background:

• Alpha-synuclein is implicated in Parkinson's disease pathogenesis.
• Its physiological functions are linked to phospholipid interactions.
• Understanding its membrane-binding conformational changes is crucial.

Purpose of the Study:

• To investigate the conformational alterations of monomeric alpha-synuclein upon binding to phospholipids.
• To elucidate the structural reorganization of alpha-synuclein during membrane interaction.

Main Methods:

• Electron Paramagnetic Resonance (EPR) spectroscopy was employed.
• 47 singly labeled alpha-synuclein derivatives were analyzed.

Main Results:

• Membrane binding induces major conformational changes in the N-terminal 11-amino acid repeats of alpha-synuclein.
• These repeats transition from a dynamic structure to an elongated, non-packed helical conformation.
• Analogous positions across different repeats exhibit similar membrane proximity, suggesting a consistent structural organization.
• A curved, membrane-dependent alpha-helical structure is proposed, with each repeat forming three helical turns.

Conclusions:

• Monomeric alpha-synuclein adopts a specific helical structure upon membrane interaction.
• This structural adaptation is mediated by its N-terminal repeats.
• Similar helical structures may be relevant for other lipid-interacting proteins, such as apolipoproteins.