Electrostatically driven lipid-lysozyme mixed fibers display a multilamellar structure without amyloid features.
Ana M Melo1, Luís M S Loura, Fábio Fernandes
1Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. ana.coutinho@ist.utl.pt.
Soft Matter
|March 22, 2014
Summary
Negatively charged lipid membranes do not generally trigger amyloid fiber formation in non-amyloidogenic proteins. Studies with hen egg-white lysozyme reveal distinct structural and dynamic properties in mixed lipid-protein fibers, lacking amyloid characteristics.
Area of Science:
- Biophysics
- Membrane Biology
- Protein Science
Background:
- Understanding membrane-protein interactions is crucial for amyloid formation mechanisms.
- Anionic lipid membranes are implicated in driving amyloidogenesis.
- Non-amyloidogenic proteins serve as models to investigate these interactions.
Purpose of the Study:
- To investigate if anionic lipid membranes can induce amyloid-like fiber formation in non-amyloidogenic proteins.
- To characterize the structure and dynamics of mixed lipid-protein fibers.
- To determine if membrane-induced structural changes occur in non-amyloidogenic proteins.
Main Methods:
- Time-resolved Förster resonance energy transfer (FRET) for structural analysis.
- Two-photon microscopy with Laurdan for membrane surface characterization.
- Infrared spectroscopy to assess protein secondary structure.
Main Results:
- Mixed lipid-lysozyme fibers exhibited a multilamellar architecture.
- Both lysozyme and phospholipids showed reduced lateral mobility within the fibers.
- Membrane surface dehydration and increased packing were observed in the mixed fibers.
- Lysozyme did not adopt a β-sheet rich structure characteristic of amyloid fibrils.
Conclusions:
- Negatively charged lipid membranes do not generally induce amyloid fibril formation in non-amyloidogenic proteins.
- The observed mixed fibers possess unique supramolecular characteristics distinct from amyloid fibrils.
- Lipid-protein interactions under these conditions do not lead to amyloidogenic structural conversion.
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