Molecular basis for ubiquitin and ISG15 cross-reactivity in viral ovarian tumor domains
Open Access
- 25 January 2011
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 108 (6), 2228-2233
- https://doi.org/10.1073/pnas.1015287108
Abstract
Crimean Congo hemorrhagic fever virus (CCHFV) is a deadly human pathogen that evades innate immune responses by efficiently interfering with antiviral signaling pathways mediated by NF-κB, IRF3, and IFNα/β. These pathways rely on protein ubiquitination for their activation, and one outcome is the modification of proteins with the ubiquitin (Ub)-like modifier interferon-stimulated gene (ISG)15. CCHFV and related viruses encode a deubiquitinase (DUB) of the ovarian tumor (OTU) family, which unlike eukaryotic OTU DUBs also targets ISG15 modifications. Here we characterized the viral OTU domain of CCHFV (vOTU) biochemically and structurally, revealing that it hydrolyzes four out of six tested Ub linkages, but lacks activity against linear and K29-linked Ub chains. vOTU cleaved Ub and ISG15 with similar kinetics, and we were able to understand vOTU cross-reactivity at the molecular level from crystal structures of vOTU in complex with Ub and ISG15. An N-terminal extension in vOTU not present in eukaryotic OTU binds to the hydrophobic Ile44 patch of Ub, which results in a dramatically different Ub orientation compared to a eukaryotic OTU–Ub complex. The C-terminal Ub-like fold of ISG15 (ISG15-C) adopts an equivalent binding orientation. Interestingly, ISG15-C contains an additional second hydrophobic surface that is specifically contacted by vOTU. These subtle differences in Ub/ISG15 binding allowed the design of vOTU variants specific for either Ub or ISG15, which will be useful tools to understand the relative contribution of ubiquitination vs. ISGylation in viral infection. Furthermore, the crystal structures will allow structure-based design of antiviral agents targeting this enzyme.Keywords
This publication has 28 references indexed in Scilit:
- Emerging Role of ISG15 in Antiviral ImmunityCell, 2010
- Structural Basis for Ubiquitin Recognition by the Otu1 Ovarian Tumor Domain ProteinJournal of Biological Chemistry, 2008
- A Deubiquitinase That Regulates Type I Interferon ProductionScience, 2007
- Ovarian Tumor Domain-Containing Viral Proteases Evade Ubiquitin- and ISG15-Dependent Innate Immune ResponsesCell Host & Microbe, 2007
- Selectivity in ISG15 and ubiquitin recognition by the SARS coronavirus papain-like proteaseArchives of Biochemistry and Biophysics, 2007
- Pathogen Recognition and Innate ImmunityCell, 2006
- Crystal Structure of the Interferon-induced Ubiquitin-like Protein ISG15Journal of Biological Chemistry, 2005
- ISG15: a ubiquitin-like enigmaFrontiers in Bioscience-Landmark, 2005
- Chemistry-Based Functional Proteomics Reveals Novel Members of the Deubiquitinating Enzyme FamilyCell Chemical Biology, 2002
- Virus-encoded proteinases and proteolytic processing in the NidoviralesJournal of General Virology, 2000