Epstein-Barr virus nuclear protein 2 (EBNA2) binds to a component of the human SNF-SWI complex, hSNF5/Ini1.
Epstein-Barr nuclear antigen 2 (EBNA2), one of the six viral nuclear proteins expressed in latently infected B lymphocytes, is essential to the immortalization of B cells by Epstein-Barr virus (EBV). EBNA2 promotes transcriptional transactivation of viral and cellular genes by acting as an adapter molecule that binds to cellular sequence-specific DNA-binding proteins, JK recombination signal-binding protein (RBP-JK), and PU.1 and engages multiple members of the RNA polymerase II transcription complex. In the present study, we show that EBNA2 also interacts with hSNF5/Ini1, the human homolog of the yeast transcription factor SNF5. Gel filtration fractionation of partially purified EBV-positive lymphocyte nuclear extracts shows that a fraction of EBNA2 coelutes with both hSNF5/Ini1 and BRG1, a human homolog of SWI/SNF2, in the high-molecular-mass region (1.5 to 2.0 MDa) of a Superose 6 chromatogram. An affinity-purified rabbit antibody directed against hSNF5/Ini1 coimmunoprecipitates EBNA2 from this high-molecular-mass nuclear protein fraction, demonstrating that EBNA2 and hSNF5/Ini1 interact in vivo. This interaction is restricted to a subpopulation of phosphorylated viral EBNA2. Deletion mutation analysis of EBNA2 shows that the proline-rich aminoterminal end and a domain within the divergent region of EBNA2 mediate EBNA2-hSNF5/Ini1 interaction. Since the SNF-SWI complex participates in gene regulation through the alteration of nucleosome configuration and may be a component of the RNA polymerase II holoenzyme, the EBNA2-hSNF5/Ini1 interaction supports the hypothesis that EBNA2 facilitates transcriptional transactivation by acting as a transcription adapter molecule. We postulate that EBNA2 engages the hSNF-SWI complex to generate an open chromatin conformation at the EBNA2-responsive target genes, thereby potentiating the function of the RBP-JK-EBNA2-polymerase II transcription complex.
Wu
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Department of Medicine, Veterans Affairs Medical Center, Seattle, Washington 98108, USA.
Kalpana
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Goff
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Schubach
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D000818:Animals; D000906:Antibodies; D000956:Antigens, Viral / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins; D002051:Burkitt Lymphoma; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D019309:Epstein-Barr Virus Nuclear Antigens; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D008214:Lymphocytes / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D012319:RNA Polymerase II / Q000378:metabolism; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D000071796:SMARCB1 Protein; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D000099160:LexA Repressor Protein
D000906:Antibodies; D000956:Antigens, Viral; D001426:Bacterial Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; D012319:RNA Polymerase II; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D000071796:SMARCB1 Protein; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099160:LexA Repressor Protein; C513266:SMARCB1 protein, human; C066190:SNF5 protein, S cerevisiae