Mapping the interacting domains between the rabies virus polymerase and phosphoprotein

Area of Science:

• Virology
• Molecular Biology
• Protein Interactions

Background:

• Rabies virus RNA polymerase is essential for viral replication.
• The polymerase comprises large (L) and phosphoprotein (P) subunits.
• Understanding subunit interactions is key to viral mechanism studies.

Purpose of the Study:

• To identify the specific regions of rabies virus L and P proteins responsible for their complex formation.
• To elucidate the molecular basis of the RNA polymerase subunit interaction.

Main Methods:

• Co-expression of L and P proteins in mammalian cells using a vaccinia virus-T7 RNA polymerase recombinant system.
• Co-immunoprecipitation assays to detect protein complex formation.
• Analysis of deletion mutants of both P and L proteins to map interaction domains.

Main Results:

• Rabies virus phosphoprotein (P) N-terminal residues (first 19) are critical for binding to the large (L) protein.
• Large deletions in the P protein's C-terminus did not disrupt L binding.
• The C-terminal domain of the L protein is essential for its interaction with the P protein.
• Deletion of 789 residues from L's C-terminus abolished P binding.

Conclusions:

• The N-terminus of the rabies virus P protein contains the primary binding site for the L protein.
• The C-terminus of the rabies virus L protein is indispensable for P protein interaction.
• These findings define the minimal interaction domains for rabies virus RNA polymerase subunit assembly.