TRIM6 facilitates SARS-CoV-2 proliferation by catalyzing the K29-typed ubiquitination of NP to enhance the ability to bind viral genomes.

ABSTRACT

The Nucleocapsid Protein (NP) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is not only the core structural protein required for viral packaging, but also participates in the regulation of viral replication, and its post-translational modifications such as phosphorylation have been shown to be an important strategy for regulating virus proliferation. Our previous work identified NP could be ubiquitinated, as confirmed by two independent studies. But the function of NP ubiquitination is currently unknown. In this study, we first pinpointed TRIM6 as the E3 ubiquitin ligase responsible for NP ubiquitination, binding to NP's CTD via its RING and B-box-CCD domains. TRIM6 promotes the K29-typed polyubiquitination of NP at K102, K347, and K361 residues, increasing its binding to viral genomic RNA. Consistently, functional experiments such as the use of the reverse genetic tool trVLP model and gene knockout of TRIM6 further confirmed that blocking the ubiquitination of NP by TRIM6 significantly inhibited the proliferation of SARS-CoV-2. Notably, the NP of coronavirus is relatively conserved, and the NP of SARS-CoV can also be ubiquitinated by TRIM6, indicating that NP could be a broad-spectrum anti-coronavirus target. These findings shed light on the intricate interaction between SARS-CoV-2 and the host, potentially opening new opportunities for COVID-19 therapeutic development.