Skip to Content
Merck
  • Herpesvirus deconjugases inhibit the IFN response by promoting TRIM25 autoubiquitination and functional inactivation of the RIG-I signalosome.

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

PLoS pathogens (2018-01-23)
Soham Gupta, Päivi Ylä-Anttila, Simone Callegari, Ming-Han Tsai, Henri-Jacques Delecluse, Maria G Masucci
ABSTRACT

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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt dihydrate, ACS reagent, 99.0-101.0%
Sigma-Aldrich
Monoclonal ANTI-FLAG® M2 antibody produced in mouse, 1 mg/mL, clone M2, affinity isolated antibody, buffered aqueous solution (50% glycerol, 10 mM sodium phosphate, and 150 mM NaCl, pH 7.4)
Sigma-Aldrich
Monoclonal Anti-polyHistidine antibody produced in mouse, clone HIS-1, ascites fluid
Sigma-Aldrich
Monoclonal Anti-β-Actin antibody produced in mouse, clone AC-15, ascites fluid
Sigma-Aldrich
Anti-RIG-I, clone 1C3 Antibody, clone 1C3, from mouse
Millipore
Monoclonal Anti-HA−Agarose antibody produced in mouse, clone HA-7, purified immunoglobulin, PBS suspension