ORF10-Cullin-2-ZYG11B complex is not required for SARS-CoV-2 infection

Abstract

In order to understand the transmission and virulence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is necessary to understand the functions of each of the gene products encoded in the viral genome. One feature of the SARS-CoV-2 genome that is not present in related, common coronaviruses is ORF10, a putative 38-amino acid protein-coding gene. Proteomic studies found that ORF10 binds to an E3 ubiquitin ligase containing Cullin-2, Rbx1, Elongin B, Elongin C, and ZYG11B (CRL2ZYG11B). Since CRL2ZYG11B mediates protein degradation, one possible role for ORF10 is to "hijack" CRL2ZYG11B in order to target cellular, antiviral proteins for ubiquitylation and subsequent proteasomal degradation. Here, we investigated whether ORF10 hijacks CRL2ZYG11B or functions in other ways, for example, as an inhibitor or substrate of CRL2ZYG11B. While we confirm the ORF10-ZYG11B interaction and show that the N terminus of ORF10 is critical for it, we find no evidence that ORF10 is functioning to inhibit or hijack CRL2ZYG11B. Furthermore, ZYG11B and its paralog ZER1 are dispensable for SARS-CoV-2 infection in cultured cells. We conclude that the interaction between ORF10 and CRL2ZYG11B is not relevant for SARS-CoV-2 infection in vitro.