Interactions between rubella virus capsid and host protein p32 are important for virus replication

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Rubella virus (RV) infection significantly alters mitochondrial distribution and morphology.
• RV capsid protein alone can induce mitochondrial perinuclear clustering and intermitochondrial plaque formation.
• The host cell mitochondrial matrix protein p32 was previously identified as a capsid-binding protein.

Purpose of the Study:

• To investigate the role of capsid-p32 interactions in rubella virus infection.
• To determine the specific regions of the capsid protein involved in p32 binding.
• To elucidate the functional consequences of disrupted capsid-p32 interactions on viral replication and mitochondrial organization.

Main Methods:

• Site-directed mutagenesis to ablate the p32-binding site on the RV capsid.
• Generation of recombinant RV encoding mutated capsid proteins.
• Analysis of mitochondrial morphology and distribution in infected cells.
• Quantification of viral RNA replication and protein synthesis.

Main Results:

• Two arginine clusters in the RV capsid are essential for stable binding to host protein p32.
• Mutational disruption of the p32-binding site reduced mitochondrial clustering and altered plaque morphology.
• Recombinant viruses with disrupted capsid-p32 interactions showed decreased viral RNA replication and lower titers.
• Impaired capsid-p32 interaction led to reduced production of viral structural proteins.

Conclusions:

• Capsid-p32 interactions are critical for rubella virus replication and pathogenesis.
• These interactions mediate nonstructural functions of the capsid protein, including regulation of viral RNA synthesis.
• Capsid-p32 binding is essential for the virus-induced reorganization of mitochondria during infection.