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.

SARS-CoV-2 ORF10 suppresses the antiviral innate immune response by degrading MAVS through mitophagy

“…Compared with the SARS-CoV genome, the SARS-CoV-2 genome uniquely encodes the ORF10 protein, which contains 38 amino acids [ 13 , 14 ]. ORF10 was reported to bind to an E3 ubiquitin ligase complex containing Cullin-2, Rbx1, Elongin B, Elongin C, and ZYG11B, which ubiquitinates host proteins and degrades them via the 26 S proteasome; ZYG11B is dispensable for SARS-CoV-2 infection, and the interaction between ORF10 and ZYG11B is not relevant for SARS-CoV-2 infection [ 15 ]. However, how ORF10 functions in the interaction between the virus and host cells is unclear.…”

Emergence of Unique SARS-CoV-2 ORF10 Variants and Their Impact on Protein Structure and Function

“…The per-residue disorder profiles for 138 unique SARS-CoV-2 ORF10 variants (vari- Here, we investigate the effects of point mutations on the overall disorder score for in ORF10 to target it for degradation [32,33].…”

Emergence of unique SARS-CoV-2 ORF10 variants and their impact on protein structure and function

“…The SARS-CoV-2 ORF10, a putative 38-amino acid viral protein encoded in the 3′ accessory region of the genome, is a highly ordered, hydrophobic, and thermally stable protein, which contains at least one transmembrane region [34] , [35] . The ORF10 binds to components of a Cullin-2-RING-ligase (CRL2) complex containing Cullin-2, RBX1, Elongin B, Elongin C, and ZYG11B ( CRL 2 ZY G 11 B ) [36] , [37] , [38] . Earlier, it has been reported that the extreme N terminus of ORF10 contains a methionine-glycine-tyrosine motif, which would presumably aid ORF10 to be recruited into the CRL 2 ZY G 11 B ubiquitin ligase complex [37] .…”

“…The ORF10 binds to components of a Cullin-2-RING-ligase (CRL2) complex containing Cullin-2, RBX1, Elongin B, Elongin C, and ZYG11B ( CRL 2 ZY G 11 B ) [36] , [37] , [38] . Earlier, it has been reported that the extreme N terminus of ORF10 contains a methionine-glycine-tyrosine motif, which would presumably aid ORF10 to be recruited into the CRL 2 ZY G 11 B ubiquitin ligase complex [37] . It was further confirmed that interaction between ORF10 and CRL 2 ZY G 11 B is not relevant for SARS-CoV-2 infection in vitro [37] , [39] .…”

“…Earlier, it has been reported that the extreme N terminus of ORF10 contains a methionine-glycine-tyrosine motif, which would presumably aid ORF10 to be recruited into the CRL 2 ZY G 11 B ubiquitin ligase complex [37] . It was further confirmed that interaction between ORF10 and CRL 2 ZY G 11 B is not relevant for SARS-CoV-2 infection in vitro [37] , [39] . There is no evidence of ORF10 regulating or being regulated by CRL 2 ZY G 11 B [37] .…”