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Structural characterization and membrane binding properties of the matrix protein VP40 of Ebola virus
R W Ruigrok1, G Schoehn, A Dessen
1Grenoble Outstation, European Molecular Biology Laboratory (EMBL), 6 rue Jules Horowitz, Grenoble, 38000, France.
Abstract:
The matrix protein VP40 of Ebola virus is believed to play a central role in viral assembly as it targets the plasma membrane of infected cells and subsequently forms a tightly packed layer on the inner side of the viral envelope. Expression of VP40 in Escherichia coli and subsequent proteolysis yielded two structural variants differing by a C-terminal truncation 114 amino acid residues long. As indicated by chemical cross-linking studies and electron microscopy, the larger polypeptide was present in a monomeric form, whereas the truncated one formed hexamers. When analyzed for their in vitro binding properties, both constructs showed that only monomeric VP40 efficiently associated with membranes containing negatively charged lipids. Membrane association of truncated, hexameric VP40 was inefficient, indicating a membrane-recognition role for the C-terminal part. Based on these observations we propose that assembly of Ebola virus involves the formation of VP40 hexamers that is mediated by the N-terminal part of the polypeptide.
Insights
Ebola virus matrix protein VP40
Area of Science:
- Virology
- Structural Biology
- Biochemistry
Background:
- Ebola virus matrix protein VP40 is crucial for viral assembly.
- VP40 targets the plasma membrane and forms a layer beneath the viral envelope.
Purpose of the Study:
- To investigate the structural and membrane-binding properties of Ebola virus VP40.
- To elucidate the role of VP40's C-terminal region in membrane association and viral assembly.
Main Methods:
- Expression of VP40 in Escherichia coli and subsequent proteolysis.
- Chemical cross-linking studies and electron microscopy to determine protein structure.
- In vitro membrane binding assays with different VP40 variants.
Main Results:
- Two VP40 variants were generated: a full-length monomer and a C-terminally truncated hexamer.
- Monomeric VP40 efficiently bound to membranes with negatively charged lipids.
- Truncated, hexameric VP40 showed inefficient membrane association.
Conclusions:
- The C-terminal part of VP40 is essential for efficient membrane recognition.
- Ebola virus assembly likely involves VP40 hexamer formation mediated by the N-terminal region.