SARS-CoV-2 Main Protease Targets Host Selenoproteins and Glutathione Biosynthesis for Knockdown via Proteolysis, Potentially Disrupting the Thioredoxin and Glutaredoxin Redox Cycles.

Content Provider	Europe PMC
Author	Gallardo, Ignacio A. Todd, Daniel A. Lima, Stella T. Chekan, Jonathan R. Chiu, Norman H. Taylor, Ethan Will
Editor	Napolitano, Alessandra
Copyright Year	2023
Abstract	Associations between dietary selenium status and the clinical outcome of many viral infections, including SARS-CoV-2, are well established. Multiple independent studies have documented a significant inverse correlation between selenium status and the incidence and mortality of COVID-19. At the molecular level, SARS-CoV-2 infection has been shown to decrease the expression of certain selenoproteins, both in vitro and in COVID-19 patients. Using computational methods, our group previously identified a set of six host proteins that contain potential SARS-CoV-2 main protease (Mpro) cleavage sites. Here we show experimentally that Mpro can cleave four of the six predicted target sites, including those from three selenoproteins: thioredoxin reductase 1 (TXNRD1), selenoprotein F, and selenoprotein P, as well as the rate-limiting enzyme in glutathione synthesis, glutamate-cysteine ligase catalytic subunit (GCLC). Cleavage was assessed by incubating recombinant SARS-CoV-2 Mpro with synthetic peptides spanning the proposed cleavage sites, and analyzing the products via UPLC-MS. Furthermore, upon incubation of a recombinant Sec498Ser mutant of the full TXNRD1 protein with SARS-CoV-2 Mpro, the predicted cleavage was observed, destroying the TXNRD1 C-terminal redox center. Mechanistically, proteolytic knockdown of both TXNRD1 and GCLC is consistent with a viral strategy to inhibit DNA synthesis, conserving the pool of ribonucleotides for increased virion production. Viral infectivity could also be enhanced by GCLC knockdown, given the ability of glutathione to disrupt the structure of the viral spike protein via disulfide bond reduction. These findings shed new light on the importance of dietary factors like selenium and glutathione in COVID-19 prevention and treatment.
Journal	Antioxidants (Basel, Switzerland)
Volume Number	12
PubMed Central reference number	PMC10045059
Issue Number	3
PubMed reference number	36978807
e-ISSN	20763921
DOI	10.3390/antiox12030559
Language	English
Publisher	MDPI
Publisher Date	2023-02-23
Access Restriction	Open
Rights License	Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). © 2023 by the authors.
Subject Keyword	COVID-19 DNA synthesis glutathione RNA SARS-CoV-2 selenium SELENOF SELENOP selenoprotein thioredoxin reductase 1
Content Type	Text
Resource Type	Article
Subject	Biochemistry Cell Biology Molecular Biology Physiology Clinical Biochemistry Food Science