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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Motifs
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Amino Acid Sequence
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Animals
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Arabidopsis Proteins*
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B-Lymphocytes / metabolism*
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Base Sequence
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Binding Sites
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Calcium-Binding Proteins / genetics
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Calcium-Binding Proteins / metabolism
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Endosomal Sorting Complexes Required for Transport
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Enzyme Precursors / genetics
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Enzyme Precursors / metabolism*
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Humans
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Intracellular Signaling Peptides and Proteins
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Ligases / genetics*
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Ligases / metabolism*
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Mice
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Molecular Sequence Data
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Mutation
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Nedd4 Ubiquitin Protein Ligases
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Protein-Tyrosine Kinases / genetics
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Protein-Tyrosine Kinases / metabolism*
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Repressor Proteins*
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Syk Kinase
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Ubiquitin-Protein Ligases
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Viral Matrix Proteins / genetics
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Viral Matrix Proteins / metabolism*
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src-Family Kinases / genetics
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src-Family Kinases / metabolism*
Substances
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ABI3-interacting protein 2, Arabidopsis
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Arabidopsis Proteins
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Calcium-Binding Proteins
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Carrier Proteins
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EBV-associated membrane antigen, Epstein-Barr virus
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Endosomal Sorting Complexes Required for Transport
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Enzyme Precursors
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Intracellular Signaling Peptides and Proteins
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Repressor Proteins
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Viral Matrix Proteins
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ITCH protein, human
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Nedd4 Ubiquitin Protein Ligases
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Nedd4 protein, human
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Nedd4L protein, human
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Nedd4l protein, mouse
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Ubiquitin-Protein Ligases
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Protein-Tyrosine Kinases
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SYK protein, human
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Syk Kinase
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Syk protein, mouse
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lyn protein-tyrosine kinase
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src-Family Kinases
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Ligases