Heat Treatment Promotes Ubiquitin-Mediated Proteolysis of SARS-CoV-2 RNA Polymerase and Decreases Viral Load

Abstract

Despite extensive efforts, COVID-19 pandemic caused by the SARS-CoV-2 virus is still at large. Vaccination is an effective approach to curb virus spread, but several variants (e.g., delta, delta plus, omicron, and IHU) appear to weaken or possibly escape immune protection. Thus, novel and quickly scalable approaches to restrain SARS-CoV-2 are urgently needed. Multiple evidences showed thermal sensitivity of SARS-CoV-2 and negative correlation between environmental temperature and COVID-19 transmission with unknown mechanism. Here, we reveal a potential mechanism by which mild heat treatment destabilizes the wild-type RNA-dependent RNA polymerase (also known as nonstructural protein 12 (NSP12)) of SARS-CoV-2 as well as the P323L mutant commonly found in SARS-CoV-2 variants, including omicron and IHU. Mechanistically, heat treatment promotes E3 ubiquitin ligase ZNF598-dependent NSP12 ubiquitination leading to proteasomal degradation and significantly decreases SARS-CoV-2 RNA copy number and viral titer. A mild daily heat treatment maintains low levels of both wild-type and P323L mutant of NSP12, suggesting clinical potential. Collectively, this novel mechanism, heat-induced NSP12 degradation, suggests a prospective heat-based intervention against SARS-CoV-2.

Translational regulation by ribosome-associated quality control in neurodegenerative disease, cancer, and viral infection

“…This result is consistent with an earlier study implicating ZNF598 E3 ligase activity and the ubiquitination of Rps20, but not Rps10, in vaccinia virus replication and the synthesis of vaccinia viral proteins whose encoding mRNAs contain unusual 5’ poly(A) leaders ( DiGiuseppe et al, 2018 ). Interestingly, a recent study showed that mild heat treatment destabilized the RNA-dependent RNA polymerase (also known as Nsp12 protein) encoded by SARS-COV2 virus in a mechanism mediated by ZNF598-dependent ubiquitination of Nsp12 ( Maimaitiyiming et al, 2022 ), suggesting a novel mechanism of action of ZNF598 in cellular response to viral infection and a new way to interfere with SARS-COV2 replication and combat the ongoing COVID-19 epidemic.…”

Protein Quality Control Systems and ER Stress as Key Players in SARS-CoV-2-Induced Neurodegeneration

“…Furthermore, different ubiquitin ligases have been identified as potent restrictors of SARS-CoV-2. Li et al (2023) showed that the E3 ligase RNF5 promotes the ubiquitination and degradation of the viral envelope protein, inhibiting SARS-CoV-2 replication [69,106]. Furthermore, tripartite motif (TRIM) proteins such as TRIM25 and TRIM56, known for their involvement in maintaining cellular proteostasis and preventing protein aggregation in neurodegenerative disorders, also contribute to the defense against COVID-19 through their ubiquitin ligase activity [107,108].…”

Role of E3 ubiquitin ligases and deubiquitinating enzymes in SARS-CoV-2 infection

“…being a crucial component of the polymerase (Wang et al, 2020). An investigation has revealed that elevated temperatures can impede the virus by facilitating nsp12 ubiquitination mediated by E3 ubiquitin ligase Zinc Finger Protein 598 (ZNF598), leading to a reduction in the quantity of viral RNA copies and a decrease in the viral concentration (Maimaitiyiming et al, 2022). Additionally, it is widely recognized that Mpro, a kind of 3CLpro, plays a crucial role in the viral replication process due to its ability to cleave viral polyproteins, releasing nsps that initiate subsequent virus transcription.…”