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A viral deubiquitylating enzyme targets viral RNA‐dependent RNA polymerase and affects viral infectivity
Author(s) -
Che Mélanie,
Camborde Laurent,
Cheminant Soizic,
Jupin Isabelle
Publication year - 2012
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2011.424
Subject(s) - biology , infectivity , virology , rna , rna dependent rna polymerase , viral structural protein , polymerase , rna polymerase , viral entry , enzyme , viral replication , virus , genetics , biochemistry , gene
Selective protein degradation via the ubiquitin‐proteasome system (UPS) plays an essential role in many major cellular processes, including host–pathogen interactions. We previously reported that the tightly regulated viral RNA‐dependent RNA polymerase (RdRp) of the positive‐strand RNA virus Turnip yellow mosaic virus (TYMV) is degraded by the UPS in infected cells, a process that affects viral infectivity. Here, we show that the TYMV 98K replication protein can counteract this degradation process thanks to its proteinase domain. In‐vitro assays revealed that the recombinant proteinase domain is a functional ovarian tumour (OTU)‐like deubiquitylating enzyme (DUB), as is the 98K produced during viral infection. We also demonstrate that 98K mediates in‐vivo deubiquitylation of TYMV RdRp protein—its binding partner within replication complexes—leading to its stabilization. Finally, we show that this DUB activity contributes to viral infectivity in plant cells. The identification of viral RdRp as a specific substrate of the viral DUB enzyme thus reveals the intricate interplay between ubiquitylation, deubiquitylation and the interaction between viral proteins in controlling levels of RdRp and viral infectivity.