tetano
Editor, Senior Moderator
Cell Rep
. 2026 Apr 17;45(4):117257.
doi: 10.1016/j.celrep.2026.117257. Online ahead of print.
Non-canonical proteolytic activation of RNase L by SARS-CoV-2 3CL[SUP]pro[/SUP] offsets inactivation of OAS1 p46 antiviral signaling
Peter A Bell[SUP] 1 [/SUP], Kaushal Baid[SUP] 2 [/SUP], Christina Pan[SUP] 1 [/SUP], Peter M Grin[SUP] 3 [/SUP], Hugo C R de Jesus[SUP] 1 [/SUP], Reinhild Kappelhoff[SUP] 1 [/SUP], Isabel Pablos[SUP] 1 [/SUP], Georgina S Butler[SUP] 1 [/SUP], Sauhard Shrivastava[SUP] 4 [/SUP], Ansalna Ansari[SUP] 4 [/SUP], Arinjay Banerjee[SUP] 5 [/SUP], Christopher M Overall[SUP] 6 [/SUP]
Affiliations
During SARS-CoV-2 infection, the key protective oligoadenylate synthetase (OAS) that activates RNase L upon sensing viral dsRNA is the membrane-anchored OAS1 isoform p46. We show that SARS-CoV-2 3C-like main protease (3CL[SUP]pro[/SUP]/M[SUP]pro[/SUP]) efficiently cleaves p46 at [SUP]381[/SUP]STLQ[SUP]384[/SUP]↓A, excising the prenylated-Cys[SUP]397[/SUP] membrane anchor, which releases p46 from endomembranes and thereby antagonizes antiviral restriction. We further show that 3CL[SUP]pro[/SUP] cleaves RNase L at [SUP]406[/SUP]SCLQ[SUP]409[/SUP]↓S, removing an inhibitory N-terminal domain and generating RNase L (410-741), a proteolytically activated antiviral effector. Non-cleavable RNase L (Gln409Ala) lacks antiviral activity in infected p46-null cells, confirming this non-canonical activation mechanism. RNA sequencing shows that protease-activated RNase L alters host RNA targeting and that 3CL[SUP]pro[/SUP] reduces OAS3 transcripts. We propose that the conserved RNase L 3CL[SUP]pro[/SUP] cleavage motif functions as a failsafe "tripwire" that preserves antiviral restriction despite p46 evasion. Thus, 3CL[SUP]pro[/SUP] not only processes viral polyproteins but also directly activates RNase L, triggering antiviral restriction and revealing an intrinsic evolutionary constraint on immune evasion.
Keywords: 2-5A-dependent ribonuclease; 3CLpro; COVID-19; CP: microbiology; Mpro; OAS1; RNase L; SARS-CoV-2; coronavirus 3C proteases; virus-host interaction.
. 2026 Apr 17;45(4):117257.
doi: 10.1016/j.celrep.2026.117257. Online ahead of print.
Non-canonical proteolytic activation of RNase L by SARS-CoV-2 3CL[SUP]pro[/SUP] offsets inactivation of OAS1 p46 antiviral signaling
Peter A Bell[SUP] 1 [/SUP], Kaushal Baid[SUP] 2 [/SUP], Christina Pan[SUP] 1 [/SUP], Peter M Grin[SUP] 3 [/SUP], Hugo C R de Jesus[SUP] 1 [/SUP], Reinhild Kappelhoff[SUP] 1 [/SUP], Isabel Pablos[SUP] 1 [/SUP], Georgina S Butler[SUP] 1 [/SUP], Sauhard Shrivastava[SUP] 4 [/SUP], Ansalna Ansari[SUP] 4 [/SUP], Arinjay Banerjee[SUP] 5 [/SUP], Christopher M Overall[SUP] 6 [/SUP]
Affiliations
- PMID: 42001419
- DOI: 10.1016/j.celrep.2026.117257
During SARS-CoV-2 infection, the key protective oligoadenylate synthetase (OAS) that activates RNase L upon sensing viral dsRNA is the membrane-anchored OAS1 isoform p46. We show that SARS-CoV-2 3C-like main protease (3CL[SUP]pro[/SUP]/M[SUP]pro[/SUP]) efficiently cleaves p46 at [SUP]381[/SUP]STLQ[SUP]384[/SUP]↓A, excising the prenylated-Cys[SUP]397[/SUP] membrane anchor, which releases p46 from endomembranes and thereby antagonizes antiviral restriction. We further show that 3CL[SUP]pro[/SUP] cleaves RNase L at [SUP]406[/SUP]SCLQ[SUP]409[/SUP]↓S, removing an inhibitory N-terminal domain and generating RNase L (410-741), a proteolytically activated antiviral effector. Non-cleavable RNase L (Gln409Ala) lacks antiviral activity in infected p46-null cells, confirming this non-canonical activation mechanism. RNA sequencing shows that protease-activated RNase L alters host RNA targeting and that 3CL[SUP]pro[/SUP] reduces OAS3 transcripts. We propose that the conserved RNase L 3CL[SUP]pro[/SUP] cleavage motif functions as a failsafe "tripwire" that preserves antiviral restriction despite p46 evasion. Thus, 3CL[SUP]pro[/SUP] not only processes viral polyproteins but also directly activates RNase L, triggering antiviral restriction and revealing an intrinsic evolutionary constraint on immune evasion.
Keywords: 2-5A-dependent ribonuclease; 3CLpro; COVID-19; CP: microbiology; Mpro; OAS1; RNase L; SARS-CoV-2; coronavirus 3C proteases; virus-host interaction.