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EMBO J. 2015 Aug 4;34(15):2078-95. doi: 10.15252/embj.201490361. Epub 2015 Jun 22.

TRIM5α requires Ube2W to anchor Lys63-linked ubiquitin chains and restrict reverse transcription.

Author information

1
MRC Centre of Medical Molecular Virology, Division of Infection and Immunity, University College London, London, UK.
2
Department of Biochemistry and HSC Core Facilities, University of Utah School of Medicine, Salt Lake City, UT, USA.
3
Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, UK.
4
MRC Centre of Medical Molecular Virology, Division of Infection and Immunity, University College London, London, UK g.towers@ucl.ac.uk.

Abstract

TRIM5α is an antiviral, cytoplasmic, E3 ubiquitin (Ub) ligase that assembles on incoming retroviral capsids and induces their premature dissociation. It inhibits reverse transcription of the viral genome and can also synthesize unanchored polyubiquitin (polyUb) chains to stimulate innate immune responses. Here, we show that TRIM5α employs the E2 Ub-conjugating enzyme Ube2W to anchor the Lys63-linked polyUb chains in a process of TRIM5α auto-ubiquitination. Chain anchoring is initiated, in cells and in vitro, through Ube2W-catalyzed monoubiquitination of TRIM5α. This modification serves as a substrate for the elongation of anchored Lys63-linked polyUb chains, catalyzed by the heterodimeric E2 enzyme Ube2N/Ube2V2. Ube2W targets multiple TRIM5α internal lysines with Ub especially lysines 45 and 50, rather than modifying the N-terminal amino group, which is instead αN-acetylated in cells. E2 depletion or Ub mutation inhibits TRIM5α ubiquitination in cells and restores restricted viral reverse transcription, but not infection. Our data indicate that the stepwise formation of anchored Lys63-linked polyUb is a critical early step in the TRIM5α restriction mechanism and identify the E2 Ub-conjugating cofactors involved.

KEYWORDS:

TRIM5α; Ube2N; Ube2W; restriction; ubiquitin

PMID:
26101372
PMCID:
PMC4551353
DOI:
10.15252/embj.201490361
[Indexed for MEDLINE]
Free PMC Article

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