Structural and functional characterization of the mumps virus phosphoprotein

Area of Science:

• Virology
• Structural Biology
• Molecular Biology

Background:

• The phosphoprotein (P) is essential for Rhabdoviridae and Paramyxoviridae replication.
• P proteins are self-associated oligomers that interact with viral components like the nucleocapsid (N) and polymerase (L).
• While functionally conserved, P proteins exhibit structural diversity across different viruses.

Purpose of the Study:

• To systematically map the domains of mumps virus (MuV) P protein.
• To investigate the interaction of MuV P with nucleocapsid-like particles (NLPs).
• To determine the structure of the MuV P oligomerization domain (POD).

Main Methods:

• Pulldown assays to identify MuV P interaction sites with NLPs.
• Surface plasmon resonance to analyze binding kinetics.
• X-ray crystallography to determine the structure of the MuV POD.

Main Results:

• MuV P interacts with NLPs via its C-terminal domain (residues 343-391) and, newly discovered, its N-terminal region (residues 1-194).
• This dual N- and C-terminal interaction with the nucleocapsid is unprecedented for negative-strand RNA viruses.
• The MuV P oligomerization domain (POD, residues 213-277) forms a tetramer with a novel arrangement of alpha-helices, positioning N- and C-terminal domains at opposite ends.

Conclusions:

• Both N- and C-terminal regions of MuV P contribute to nucleocapsid binding.
• The determined structure of the MuV POD reveals a unique tetrameric assembly.
• The structural findings support the observed dual-domain interaction with the nucleocapsid.