SARS-CoV-2 Nsp2 recruits GIGYF2 near viral replication sites and supports viral protein production [nsp2_del_rna_seq]

The SARS-CoV-2 genome encodes 16 non-structural proteins (Nsps), with Nsp2 being the least conserved and least understood. In this study, we found a crucial role of Nsp2 in the SARS-CoV-2 life cycle and demonstrated its interaction with GIGYF2, which causes the relocation of GIGYF2 to near double membrane vesicles (DMVs) and the enhancement of viral protein production. Deletion of the Nsp2-coding region from the viral genome led to a drastic reduction in viral RNA synthesis early in infection (3–4 hours post infection). Through interactome analysis of Nsp2 in virus-infected cells, we identified GIGYF2—a protein involved in translational regulation—as a key partner of Nsp2. We confirm the interaction between GIGYF2 and Nsp2 from both SARS-CoV-1 and SARS-CoV-2. Depleting GIGYF2 or its cofactor ZNF598 phenocopied the replication defects observed with Nsp2 deletion, suggesting their critical roles in viral reproduction. Moreover, GIGYF2 and ZNF598 relocate to areas near DMVs, viral replication sites, upon infection. This relocation does not happen with the Nsp2-deleted virus, indicating Nsp2’s role in directing GIGYF2 to DMVs. Using formaldehyde crosslinking and immunoprecipitation-sequencing experiments (fCLIP-seq), we found that GIGYF2 interacts with viral RNAs, particularly in regions encoding Nsp3, M, and Orf6. Depletion of GIGYF2 resulted in decreased expression of these proteins. Our findings reveal the function of Nsp2 in supporting viral protein production by exploiting GIGYF2 as a host factor.