Paramyxovirus F1 protein has two fusion peptides: implications for the mechanism of membrane fusion

Area of Science:

• Virology
• Membrane Biology
• Protein Chemistry

Background:

• Viral fusion proteins mediate the merging of viral and host cell membranes.
• Paramyxoviruses are thought to possess a single N-terminal fusion peptide on their F1 protein.

Purpose of the Study:

• To investigate potential additional fusion peptide regions within the Sendai virus F1 protein.
• To functionally characterize a newly identified internal segment of the F1 protein.

Main Methods:

• Sequence homology analysis comparing F1 protein segments to known viral fusion peptides.
• Synthesis and functional assay of peptides to assess membrane fusion induction.
• Utilizing large unilamellar vesicles for membrane fusion studies.

Main Results:

• An internal segment (amino acids 214-226) of the Sendai virus F1 protein showed high homology to known fusion peptides.
• Synthetic peptides from this internal region induced membrane fusion, unlike scrambled or other F1 peptides.
• The N-terminal fusion peptide was less effective at the concentrations used for the internal peptide.

Conclusions:

• The Sendai virus F1 protein contains an additional, functional internal fusion peptide.
• This internal fusion peptide likely plays a role in the viral membrane fusion process.
• The dual fusion peptide mechanism may be a conserved feature among paramyxoviruses.