Oligomerization of Mumps Virus Phosphoprotein

Area of Science:

• Virology
• Molecular Biology

Background:

• Mumps virus (MuV) is a significant human pathogen.
• The viral phosphoprotein (P) is crucial for MuV RNA synthesis, forming part of the RNA-dependent RNA polymerase complex with the L protein.
• The P protein has three domains: N-terminal (P(N)), oligomerization (P(O)), and C-terminal (P(C)), with P(N) known to affect RNA binding, but the roles of P(O) and P(C) remain unclear.

Purpose of the Study:

• To elucidate the roles of the P(O) and P(C) domains in MuV RNA synthesis.
• To investigate the structural and functional relationships of the MuV P protein domains.
• To establish a trans-complementation system for studying P protein function.

Main Methods:

• Utilized mutational analysis to study the P protein domains.
• Employed a novel minigenome system to assess P protein function and domain complementation.
• Investigated protein-protein interactions, specifically P-L interactions and P self-association.

Main Results:

• Demonstrated that P(N) and P(C) functions can be complemented in trans, but this requires the P(O) domain, highlighting its essential role.
• Confirmed that MuV P protein forms parallel dimers (P(N)-P(N) and P(C)-P(C)).
• Identified critical residues (R231, K238, K253, K260) within the P(O) domain essential for P function and confirmed P(C) interacts with the L protein.

Conclusions:

• The P(O) domain is essential for MuV P protein function and its ability to form parallel dimers.
• The P(C) domain directly interacts with the L protein, contributing to the RNA polymerase complex.
• These findings provide crucial structure-function insights into MuV P protein's role in viral RNA synthesis, potentially aiding vaccine and antiviral development.