Ubiquitination of the Epstein-Barr virus-encoded latent membrane protein 1 depends on the integrity of the TRAF binding site.
The latent membrane protein 1 (LMP1) encoded by the Epstein-Barr virus functions as a constitutively activated receptor of the tumor necrosis factor receptor family. LMP1 is a short-lived protein that is ubiquitinated and degraded by the proteasome. We have previously shown that LMP1 recruits the adapter protein tumor necrosis factor receptor-associated factor 3 (TRAF3) to lipid rafts. To test if TRAFs are involved in LMP1's ubiquitination, we have mutated the LMP1 CTAR1 site that has been identified as a TRAF binding site. We show that the CTAR1 mutant (CTAR1(-)) is expressed after transfection at a similar level to wild-type LMP1, and behaves as wild-type LMP1 with respect to membrane localization. However, CTAR1(-) does not bind TRAF3. We demonstrate that ubiquitination of CTAR1(-) is significantly reduced when compared to wild-type LMP1. In addition, the expression of wild-type LMP1 induces the ubiquitination, an effect that is significantly reduced when the CTAR1(-) is expressed. Taken together, our results suggest that TRAF proteins are involved in the ubiquitination of LMP1, and that their binding to LMP1 may facilitate their own ubiquitination.
Rothenberger
Sylvia
S
Institute of Biochemistry, University of Lausanne, ch. des Boveresses 155, 1066 Epalinges, Switzerland. Sylvia.RothenbergerAubert@ib.unil.ch
Burns
Kimberly
K
Rousseaux
Marga
M
Tschopp
Jürg
J
Bron
Claude
C
D001665:Binding Sites; D004789:Enzyme Activation; D006801:Humans; D051550:I-kappa B Kinase; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D048008:TNF Receptor-Associated Factor 3; D025801:Ubiquitin / Q000378:metabolism*; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000378:metabolism*
C037662:EBV-associated membrane antigen, Epstein-Barr virus; D011506:Proteins; D048008:TNF Receptor-Associated Factor 3; D025801:Ubiquitin; D014763:Viral Matrix Proteins; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human