SARS Plpro/papain-like protease Protein (His-Avi)

The SARS Plpro/papain-like protease protein emerges as a multifunctional orchestrator in the intricate landscape of transcription and replication of viral RNAs, wielding crucial proteinases for polyprotein cleavages. Operating strategically, it impedes host translation by interacting with the 40S ribosomal subunit, and the ensuing nsp1-40S ribosome complex induces an endonucleolytic cleavage near the 5'UTR of host mRNAs, effectively targeting them for degradation. Notably, viral mRNAs deploy a defense mechanism against this degradation, as they are not susceptible to nsp1-mediated endonucleolytic RNA cleavage, owing to the protective presence of a 5'-end leader sequence. Through the suppression of host gene expression, nsp1 facilitates efficient viral gene expression within infected cells while evading host immune responses. Additionally, the protein may disrupt nuclear pore function by binding and displacing host NUP93. The multifaceted functionalities of SARS Plpro highlight its pivotal role in shaping the viral life cycle and evading host defenses.