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

Yasen Maimaitiyiming,Fudi Wang,Mikael Björklund,Tao Yang,Hua Naranmandura,Chih-Hung Hsu,Yan Feng,Chonggao Hu,Qian Qian Wang,Zhi Chen

doi:10.34133/2022/9802969

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.

Highlights

Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2), the culprit of the coronavirus disease 2019 (COVID-19) pandemic, is highly contagious and transmissible among humans [1]
We found that P323L mutant and wild-type (WT) NSP12 display similar heat sensitivity (Figure 1(c)), suggesting that heat treatment could be a potential intervention against SARS-CoV-2 variants regardless of their RNA polymerase mutation status
We investigated which E3 ubiquitin ligase is involved in heat-mediated degradation of NSP12

Summary

Main Text

Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2), the culprit of the coronavirus disease 2019 (COVID-19) pandemic, is highly contagious and transmissible among humans [1]. Several studies including ours have revealed remarkable effects of hyperthermia (elevating body temperature beyond normal) or fever in selectively affecting the properties (e.g., stability, posttranslational modification, and ability to interact with other molecules) of oncogenic proteins [10–12]. Taken together, these findings imply that heat treatment might inhibit SARS-CoV-2 virulence through targeting key viral proteins, which merits particular investigation. Daily mild heat treatment (40°C, 0.5 h/day) is sufficient to maintain low levels of both WT and P323L mutant of NSP12 (Figures 1(n) and 1(o), compare lanes 3, 4 to 1), suggesting clinical potential of heat treatment against both WT and P323L mutation harboring SARS-CoV-2 variants. Fever-range and clinically relevant hyperthermia-based approaches could be rapidly developed for currently prevalent and emerging SARS-CoV-2 variants harboring P323L mutation, including delta, delta plus, omicron, and IHU

Conflicts of Interest

Findings

Materials and Methods