Functional interaction between paramyxovirus fusion and attachment proteins

Area of Science:

• Virology
• Structural Biology
• Molecular Interactions

Background:

• Paramyxovirinae envelope glycoproteins mediate viral entry through complex interactions.
• Identifying specific residues governing attachment (H) and fusion (F) protein specificity is crucial but challenging.
• Existing models lack detailed residue-level understanding of H-F protein reciprocal specificity.

Purpose of the Study:

• To identify individual amino acid residues that determine the reciprocal specificity between measles virus (MV) attachment (H) and fusion (F) proteins.
• To develop a functional assay for dissecting glycoprotein interactions within the Paramyxovirinae subfamily.
• To elucidate the molecular basis of functional complex formation between viral glycoproteins.

Main Methods:

• Developed a functional assay using canine distemper virus (CDV) F protein variants and measles virus (MV) H protein.
• Employed chimera analysis and site-directed mutagenesis of CDV F and MV H proteins.
• Utilized co-immunoprecipitation to assess physical interactions between viral glycoproteins.
• Analyzed surface expression and hemadsorption activity of engineered viral glycoproteins.

Main Results:

• Identified four key residues in CDV F-ODP (164, 219, 233, 317) essential for productive interaction with MV H.
• Mutations disrupting MV H interaction with CDV F-ODP did not affect CDV H interaction.
• Co-immunoprecipitation revealed stronger physical interaction between MV H and CDV F-ODP compared to CDV F-Lederle.
• A five-residue fragment (110-114) in the MV H stalk mediated specificity for CDV F-Lederle.
• Interdependent contributions of identified residues in both F and H proteins to functional complex formation were observed.

Conclusions:

• Pinpointed specific residues in CDV F and MV H glycoproteins critical for mediating reciprocal specificity.
• Demonstrated that these identified residues contribute interdependently to the formation of functional viral glycoprotein complexes.
• Structural modeling suggests close proximity between key residues F-233 and H stalk region 110-114, providing a structural basis for specificity.