Epstein-Barr nuclear antigen-3 and -4 interact with RBP-2N, a major isoform of RBP-J kappa in B lymphocytes.
The Epstein-Barr nuclear antigen (EBNA)-3 and EBNA-4 proteins are thought to act as transcriptional transactivators. The yeast two-hybrid system and coimmunoprecipitation were used to demonstrate that EBNA-3 and -4 associate with the DNA-binding protein RBP-2N, an isoform of RBP-J kappa. A comparison between EBNA-3, EBNA-4, and EBNA-6 binding to RBP-2N indicated that EBNA-3 enhanced beta-galactosidase activity 4-fold more than EBNA-6 and 30-fold more than EBNA-4. Assay of RBP-2N deletion mutants demonstrated that EBNA-3 binds to regions of RBP-2N which are distinct from those to which EBNA-2 and -6 interact, whereas EBNA-4 binds to the same region of RBP-2N as EBNA-2 and -6 (amino acids 159-331 of RBP-2N). Interaction of both A- and B-type EBNA-3 with RBP-2N was also demonstrated by immunoprecipitation. RT-PCR analysis of a panel of B cell lymphomas and lymphoblastoid cell lines demonstrated that higher levels of RBP-2N were expressed, in comparison to RBP-J kappa, indicating that RBP-2N is a major isoform expressed in B cells. These results suggest that all the EBNA-3 family proteins lead to transcriptional regulation via interaction with RBP-2N.
Krauer
K G
KG
Queensland Institute of Medical Research, Bancroft Centre, Australia. keniaK@qimr.edu.au
Kienzle
N
N
Young
D B
DB
Sculley
T B
TB
D001402:B-Lymphocytes / Q000378:metabolism* / Q000821:virology; D002460:Cell Line; D004789:Enzyme Activation; D019309:Epstein-Barr Virus Nuclear Antigens / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D006801:Humans; D011233:Precipitin Tests; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017384:Sequence Deletion; D014407:Tumor Cells, Cultured; D001616:beta-Galactosidase / Q000378:metabolism
D019309:Epstein-Barr Virus Nuclear Antigens; C086925:RBP-2N protein, human; D012097:Repressor Proteins; D001616:beta-Galactosidase