Herpesvirus deconjugases inhibit the IFN response by promoting TRIM25 autoubiquitination and functional inactivation of the RIG-I signalosome

PLoS Pathog. 2018 Jan 22;14(1):e1006852. doi: 10.1371/journal.ppat.1006852. eCollection 2018 Jan.


The N-terminal domains of the herpesvirus large tegument proteins encode a conserved cysteine protease with ubiquitin- and NEDD8-specific deconjugase activity. The proteins are expressed during the productive virus cycle and are incorporated into infectious virus particles, being delivered to the target cells upon primary infection. Members of this viral enzyme family were shown to regulate different aspects of the virus life cycle and the innate anti-viral response. However, only few substrates have been identified and the mechanisms of these effects remain largely unknown. In order to gain insights on the substrates and signaling pathways targeted by the viral enzymes, we have used co-immunoprecipitation and mass spectrometry to identify cellular proteins that interact with the Epstein-Barr virus encoded homologue BPLF1. Several members of the 14-3-3-family of scaffold proteins were found amongst the top hits of the BPLF1 interactome, suggesting that, through this interaction, BPLF1 may regulate a variety of cellular signaling pathways. Analysis of the shared protein-interaction network revealed that BPLF1 promotes the assembly of a tri-molecular complex including, in addition to 14-3-3, the ubiquitin ligase TRIM25 that participates in the innate immune response via ubiquitination of cytosolic pattern recognition receptor, RIG-I. The involvement of BPLF1 in the regulation of this signaling pathway was confirmed by inhibition of the type-I IFN responses in cells transfected with a catalytically active BPLF1 N-terminal domain or expressing the endogenous protein upon reactivation of the productive virus cycle. We found that the active viral enzyme promotes the dimerization and autoubiquitination of TRIM25. Upon triggering of the IFN response, RIG-I is recruited to the complex but ubiquitination is severely impaired, which functionally inactivates the RIG-I signalosome. The capacity to bind to and functionally inactivate the RIG-I signalosome is shared by the homologues encoded by other human herpesviruses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Nucleus / metabolism
  • Cells, Cultured
  • DEAD Box Protein 58 / metabolism*
  • HEK293 Cells
  • HeLa Cells
  • Herpesviridae / enzymology*
  • Humans
  • Interferons / pharmacology*
  • Receptors, Immunologic
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Transcription Factors / metabolism*
  • Tripartite Motif Proteins / metabolism*
  • Ubiquitin / metabolism
  • Ubiquitin-Protein Ligases / metabolism*
  • Ubiquitination
  • Viral Regulatory and Accessory Proteins / physiology*
  • Virus Replication


  • BPLF1 protein, Epstein-Barr virus
  • Receptors, Immunologic
  • Transcription Factors
  • Tripartite Motif Proteins
  • Ubiquitin
  • Viral Regulatory and Accessory Proteins
  • Interferons
  • TRIM25 protein, human
  • Ubiquitin-Protein Ligases
  • RIGI protein, human
  • DEAD Box Protein 58

Grants and funding

This study was supported by grants awarded by the Swedish Cancer Society, the Swedish Medical Research Council, the EU 7th Framework program ERA-NET (Infect-ERA; project eDEVILLI), the Konung Gustav V:e och Drottning Viktoria Frimurarstiftelse and the Karolinska Institutet, Stockholm, Sweden. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.