Structure and stabilization of the Hendra virus F glycoprotein in its prefusion form

Area of Science:

• Structural biology
• Virology
• Molecular biology

Background:

• Hendra virus (HeV) is a Biosafety Level 4 (BSL-4) paramyxovirus with high human mortality.
• Paramyxovirus entry relies on the fusion (F) protein, which mediates viral and host cell membrane fusion.
• The F protein undergoes conformational changes from prefusion to postfusion states to facilitate viral entry.

Purpose of the Study:

• To determine the crystal structure of the Hendra virus fusion (F) protein in its prefusion conformation.
• To investigate the structural similarities and differences between HeV F and other paramyxovirus F proteins.
• To identify key regions and residues involved in F protein function and conformational stability.

Main Methods:

• X-ray crystallography to determine the prefusion structure of the HeV F ectodomain.
• Site-directed mutagenesis to create functional assays for F protein mutants.
• Disulfide bond engineering to stabilize specific F protein conformations.

Main Results:

• The crystal structure of the prefusion HeV F ectodomain was determined, showing high similarity to parainfluenza virus 5 (PIV5) F.
• Structural differences were noted in membrane-distal apical loops and the fusion peptide cleavage loop.
• Functional assays indicated that apical loop perturbations are tolerated, except for residues critical for fold stability.
• Structure-based disulfide mutants successfully stabilized the F protein in its prefusion conformation, inhibiting fusion.

Conclusions:

• The prefusion structure of HeV F provides a detailed molecular understanding of paramyxovirus entry mechanisms.
• Stabilizing the F protein in its prefusion state effectively inhibits viral fusion.
• Targeting the prefusion conformation of the HeV F protein represents a potential strategy for antiviral therapies against henipaviruses.