title: Latent membrane protein 2A of Epstein-Barr virus binds WW domain E3 protein-ubiquitin ligases that ubiquitinate B-cell tyrosine kinases.
abstract: The latent membrane protein (LMP) 2A of Epstein-Barr virus (EBV) is implicated in the maintenance of viral latency and appears to function in part by inhibiting B-cell receptor (BCR) signaling. The N-terminal cytoplasmic region of LMP2A has multiple tyrosine residues that upon phosphorylation bind the SH2 domains of the Syk tyrosine kinase and the Src family kinase Lyn. The LMP2A N-terminal region also has two conserved PPPPY motifs. Here we show that the PPPPY motifs of LMP2A bind multiple WW domains of E3 protein-ubiquitin ligases of the Nedd4 family, including AIP4 and KIAA0439, and demonstrate that AIP4 and KIAA0439 form physiological complexes with LMP2A in EBV-positive B cells. In addition to a C2 domain and four WW domains, these proteins have a C-terminal Hect catalytic domain implicated in the ubiquitination of target proteins. LMP2A enhances Lyn and Syk ubiquitination in vivo in a fashion that depends on the activity of Nedd4 family members and correlates with destabilization of the Lyn tyrosine kinase. These results suggest that LMP2A serves as a molecular scaffold to recruit both B-cell tyrosine kinases and C2/WW/Hect domain E3 protein-ubiquitin ligases. This may promote Lyn and Syk ubiquitination in a fashion that contributes to a block in B-cell signaling. LMP2A may potentiate a normal mechanism by which Nedd4 family E3 enzymes regulate B-cell signaling.
authors.affiliation: Karolinska Institutet, Microbiology and Tumor Biology Center (MTC), SE-171 77 Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Winberg
authors.forename: L
authors.initials: L
authors.lastname: Matskova
authors.forename: F
authors.initials: F
authors.lastname: Chen
authors.forename: P
authors.initials: P
authors.lastname: Plant
authors.forename: D
authors.initials: D
authors.lastname: Rotin
authors.forename: G
authors.initials: G
authors.lastname: Gish
authors.forename: R
authors.initials: R
authors.lastname: Ingham
authors.forename: I
authors.initials: I
authors.lastname: Ernberg
authors.forename: T
authors.initials: T
authors.lastname: Pawson
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D029681:Arabidopsis Proteins; D001402:B-Lymphocytes / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008025:Ligases / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D000075702:Nedd4 Ubiquitin Protein Ligases; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins; D000072377:Syk Kinase; D044767:Ubiquitin-Protein Ligases; D014763:Viral Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: C408686:ABI3-interacting protein 2, Arabidopsis; D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; C037662:EBV-associated membrane antigen, Epstein-Barr virus; D056827:Endosomal Sorting Complexes Required for Transport; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D012097:Repressor Proteins; D014763:Viral Matrix Proteins; C432966:ITCH protein, human; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; C000618485:Nedd4L protein, human; C000618461:Nedd4l protein, mouse; D044767:Ubiquitin-Protein Ligases; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; C000606897:Syk protein, mouse; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D008025:Ligases