Phosphorylation of SARS-CoV-2 Orf9b regulates its targeting to two binding sites in TOM70 and recruitment of Hsp90
- SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is the causative agent of the COVID19 pandemic. The SARS-CoV-2 genome encodes for a small accessory protein termed Orf9b, which targets the mitochondrial outer membrane protein TOM70 in infected cells. TOM70 is involved in a signaling cascade that ultimately leads to the induction of type I interferons (IFN-I). This cascade depends on the recruitment of Hsp90-bound proteins to the N-terminal domain of TOM70. Binding of Orf9b to TOM70 decreases the expression of IFN-I; however, the underlying mechanism remains elusive. We show that the binding of Orf9b to TOM70 inhibits the recruitment of Hsp90 and chaperone-associated proteins. We characterized the binding site of Orf9b within the C-terminal domain of TOM70 and found that a serine in position 53 of Orf9b and a glutamate in position 477 of TOM70 are crucial for the association of both proteins. A phosphomimetic variant Orf9b\(_{S53E}\) showed drastically reduced binding to TOM70 and did not inhibit Hsp90 recruitment, suggesting that Orf9b-TOM70 complex formation is regulated by phosphorylation. Eventually, we identified the N-terminal TPR domain of TOM70 as a second binding site for Orf9b, which indicates a so far unobserved contribution of chaperones in the mitochondrial targeting of the viral protein.
Author: | Lukas BrandhermORCiDGND, Antonio Mario KobašGND, Mara KlöhnORCiDGND, Yannick BrüggemannGND, Stephanie PfänderORCiDGND, Joachim RassowORCiDGND, Sebastian KreimendahlORCiDGND |
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URN: | urn:nbn:de:hbz:294-89733 |
DOI: | https://doi.org/10.3390/ijms22179233 |
Parent Title (English): | International journal of molecular sciences |
Publisher: | MDPI |
Place of publication: | Basel |
Document Type: | Article |
Language: | English |
Date of Publication (online): | 2022/05/20 |
Date of first Publication: | 2021/08/26 |
Publishing Institution: | Ruhr-Universität Bochum, Universitätsbibliothek |
Tag: | Interferon; Open Access Fonds B.1.1.7; COVID19; Hsp90; Orf9b; SARS-CoV-2; TOM70; mitochondria; variant of concern |
Volume: | 22 |
Issue: | 17 |
First Page: | 9233-1 |
Last Page: | 9233-19 |
Note: | Article Processing Charge funded by the Open Access Publication Fund of Ruhr-Universität Bochum. |
Institutes/Facilities: | Institut für Hygiene und Mikrobiologie, Abteilung für Molekulare und Medizinische Virologie |
Institut für Biochemie und Pathobiochemie | |
Dewey Decimal Classification: | Naturwissenschaften und Mathematik / Chemie, Kristallographie, Mineralogie |
open_access (DINI-Set): | open_access |
faculties: | Fakultät für Chemie und Biochemie |
Licence (English): | Creative Commons - CC BY 4.0 - Attribution 4.0 International |