期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 291, 期 12, 页码 6281-6291出版社
ELSEVIER
DOI: 10.1074/jbc.M115.710632
关键词
deubiquitylation (deubiquitination); DNA viruses; viral protein; virology; X-ray crystallography; KSHV; USP7; vIRF1
资金
- Canadian Institutes of Health Research (CIHR) [106583]
- Canada Foundation for Innovation Leaders Opportunity Fund Program
- Ontario Research Fund Research Infrastructure Program
Viral interferon regulatory factor 1 (vIRF1), a Kaposi sarcoma herpesvirus protein, destabilizes p53 by inhibiting p53 acetylation and Hdm2 phosphorylation. This leads to increased ubiquitination and degradation of p53 by Hdm2, which cripples the cellular p53-mediated antiviral response. Ubiquitin-specific protease 7 (USP7) deubiquitinates p53 and Hdm2 and regulates their stability. We identified an EGPS consensus sequence in vIRF1, which is identical to that found in Epstein-Barr virus nuclear antigen 1 (EBNA1) that interacts with the N-terminal domain of USP7 (USP7-NTD). GST pulldown assays demonstrated that vIRF1 interacts with USP7-NTD via its EGPS motif. NMR heteronuclear single quantum correlation (HSQC) analysis revealed chemical perturbations after titration of USP7-NTD with vIRF1 (44)SPGEGPSGTG(53) peptide. In contrast, these perturbations were reduced with a mutant vIRF1 peptide, (44)SPGEGPAGTG(53). Fluorescence polarization analysis indicated that the vIRF1 peptide interacted with USP7-NTD with a K-d of 2.0 m. The crystal structure of the USP7-NTDvIRF1 peptide complex revealed an identical mode of binding as that of the EBNA1 peptide to USP7-NTD. We also showed that USP7 interacts with vIRF1 in U2OS cells. Decreased levels of p53, but not Hdm2 or ataxia telangiectasia-mutated (ATM), were seen after expression of vIRF1, but not with a vIRF1 mutant protein. Our results support a new role for vIRF1 through deregulation of the deubiquitinating enzyme USP7 to inhibit p53-mediated antiviral responses.
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