Mechanistic study reveals MYCBP2-mediated serine ubiquitination stabilizes SARS-CoV-2 RdRp to promote viral replication, highlighting an atypical post-translational regulatory mechanism.
Key Points
To investigate the ubiquitination landscape of SARS-CoV-2 proteins, focusing on the RNA-dependent RNA polymerase NSP12 and its regulatory mechanisms.
Screened SARS-CoV-2 viral proteins for ubiquitination during infection and evaluated differential ubiquitin chain linkage across multiple coronaviruses.
Identified the responsible host E3 ligase using cellular assays to examine its site-specificity and effect on viral replication.
Constructed a site-directed mutant (S564A) in SARS-CoV-2 NSP12 across three independent viral recovery attempts to evaluate its functional requirement.
Identified that SARS-CoV-2 NSP12 associates primarily with K63-linked polyubiquitin chains, enhancing its stability relative to human coronavirus OC43 NSP12, which associates with K48-linked chains.
Demonstrated that the atypical host E3 ligase MYCBP2 catalyzes non-canonical serine ubiquitination on NSP12 residue serine-564, actively promoting viral replication in cell culture.
Observed that substitution of the targeted residue (S564A) completely prevented the recovery of infectious virus across three independent attempts.