Protein-protein interactions between Epstein-Barr virus nuclear antigen-LP and cellular gene products: binding of 70-kilodalton heat shock proteins.
The EBNA-LP protein encoded by the open reading frame in the leader exons of the Epstein-Barr nuclear antigen messages is essential for efficient immortalization of B lymphocytes. Protein-protein interaction studies using affinity precipitation of proteins from [35S]methionine-labeled cell lysates and bacterially expressed maltose binding protein EBNA-LP fusions were performed. A cellular 68/72-kDa doublet protein was detected. This banding pattern was shown to be identical to that obtained in affinity precipitations with fusions of glutathione-S-transferase and Sp1 (a basal transcription factor). For both EBNA-LP and Sp1 the specific interacting cellular proteins have been identified as heat shock proteins (HSP) 72/73. Affinity precipitation of HSP 72/73 with deletion mutants of EBNA-LP maps the interaction domain on EBNA-LP to exon Y2 which is required for immortalization. Immunoprecipitation of EBNA-LP from EBV-positive lymphoblastoid cell lines coprecipitated the HSP 72/73 proteins, indicating that the interaction occurs in vivo as well as in vitro. The association of HSPs with a widening range of nuclear proteins involved in gene expression and proliferation control now includes Sp1 and EBNA-LP and suggests that there is a central role for molecular chaperones in these processes.
Kitay
M K
MK
Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pennsylvania 15261, USA.
Rowe
D T
DT
D000956:Antigens, Viral / Q000276:immunology*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000276:immunology*; D019309:Epstein-Barr Virus Nuclear Antigens; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000378:metabolism*; D006801:Humans; D008214:Lymphocytes / Q000166:cytology; D011233:Precipitin Tests; D011485:Protein Binding; D016160:Retinoblastoma Protein / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000956:Antigens, Viral; D004268:DNA-Binding Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; D018840:HSP70 Heat-Shock Proteins; D016160:Retinoblastoma Protein; D016329:Sp1 Transcription Factor