Binding of hnRNP I-vRNA Regulates Sindbis Virus Structural Protein Expression to Promote Particle Infectivity

Area of Science:

• Virology
• Molecular Biology
• RNA-protein interactions

Background:

• Alphaviruses, like Sindbis virus (SINV), cause significant febrile illness and arthritis.
• Host heterogeneous nuclear ribonucleoprotein (hnRNP) proteins bind to SINV RNAs.
• Disrupting these RNA-protein interactions leads to decreased viral titers and enhanced structural protein expression.

Purpose of the Study:

• To determine if the loss of hnRNP binding or sequence changes caused SINV attenuation.
• To elucidate the precise mechanisms of enhanced gene expression due to disrupted hnRNP interactions.

Main Methods:

• Utilized a protein tethering approach to restore hnRNP binding without native sequences.
• Reconstituted hnRNP I interaction using bovine immunodeficiency virus transactivation response (BIV-TAR) RNA and TAT-tagged proteins.
• Compared phenotypes of restored binding to wild-type and disrupted SINV.

Main Results:

• Restoring hnRNP I binding via the BIV-TAR/TAT system normalized SINV phenotypes.
• This included a decrease in viral structural protein expression.
• The native nucleotide sequence was not required for hnRNP I to regulate viral gene expression.

Conclusions:

• hnRNP I binding, not the specific RNA sequence, is critical for regulating SINV structural protein expression.
• This study clarifies the role of hnRNPs in controlling alphavirus replication.
• Protein tethering is a viable method to study RNA-protein interactions in viral systems.