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Characterizing the Lassa Virus Envelope Glycoprotein Membrane Proximal External Region for Its Role in Fusogenicity
Junyuan Cao1,2, Guangshun Zhang1,3, Minmin Zhou1,2
1State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, China.
Abstract:
The membrane-proximal external region (MPER) of Lassa virus (LASV) glycoprotein complex (GPC) is critical in modulating its functionality. Till now, the high-resolution structure of the intact GPC, including MPER is not available. In this study, we used alanine substitution to scan all 16 residues located in LASV MPER. Western blotting and quantification fusion assay showed that the residues located at the C terminus of the HR2 (M414 and L415) and N terminus of the MPER (K417 and Y419) are critical for GPC-mediated membrane fusion function. Furthermore, cell surface biotinylation experiments revealed that M414A, K417A and Y419A expressed similar levels as WT, whereas L415A mutant led to a reduction of mature GPC on the cell surface. Moreover, substitution of these residues with the similar residue such as M414L, L415I, K417R and Y419F would partly compensate the loss of the fusion activity caused by the alanine mutant in these sites. Results from this study showed that several key residues in the MPER region are indispensable to promote the conformational changes that drive fusion events and shed light on the structure analysis of LASV GPC and anti-LASV therapeutics.
Insights
Key residues in the Lassa virus glycoprotein complex membrane-proximal external region are vital for membrane fusion. Alanine substitutions identified critical sites (M414, L415, K417, Y419) essential for fusion function.
Area of Science:
- Virology
- Structural Biology
- Molecular Biology
Background:
- The Lassa virus glycoprotein complex (GPC) mediates viral entry.
- The membrane-proximal external region (MPER) of GPC is crucial for function.
- High-resolution structures of the intact GPC, including MPER, are currently unavailable.
Purpose of the Study:
- To investigate the functional role of individual residues within the LASV MPER.
- To identify key residues essential for GPC-mediated membrane fusion.
- To provide insights into LASV GPC structure and potential therapeutic targets.
Main Methods:
- Alanine substitution scanning of all 16 MPER residues.
- Western blotting to assess protein expression levels.
- Quantification fusion and cell surface biotinylation assays to evaluate fusion activity and GPC maturation.
Main Results:
- Residues M414, L415, K417, and Y419 were identified as critical for membrane fusion.
- L415A mutation reduced mature GPC levels on the cell surface.
- Conservative substitutions partially restored fusion activity, indicating residue-specific importance.
Conclusions:
- Specific MPER residues are indispensable for LASV GPC fusion.
- These residues likely play a role in conformational changes driving membrane fusion.
- Findings contribute to understanding LASV GPC structure and developing antiviral therapies.
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