EBNA-2 transactivates a lymphoid-specific enhancer in the BamHI C promoter of Epstein-Barr virus.
Among the few Epstein-Barr virus (EBV) genes expressed during latency are the Epstein-Barr nuclear antigens (EBNAs), at least one of which contributes to the ability of the virus to transform B lymphocytes. We have analyzed a promoter located in the BamHI-C fragment of EBV which is responsible for the expression of EBNA-1 in some cell lines. Deletion analysis of a 1.4-kb region 5' of the RNA start site has identified a 700-bp fragment that is required for optimal promoter activity in latently infected B lymphocytes, as shown by promoter constructs linked to the chloramphenicol acetyltransferase reporter gene. This fragment is also able to enhance activity, in an orientation-independent manner, of the simian virus 40 early promoter linked to the chloramphenicol acetyltransferase gene. The enhancer element has some constitutive activity in EBV-negative lymphoid cells, which is increased in the presence of the EBNA-2 gene product. Further deletions have shown that the EBNA-2-responsive region requires a 98-bp region that contains a degenerate octamer-binding motif. In epithelial cells there was no enhancer activity regardless of the presence of EBNA-2. These results demonstrate that BamHI-C promoter activity may be dependent not on an enhancer contained in the ori-P, as was previously assumed, but rather on EBNA-2 transactivation of this more proximal enhancer located in the upstream region of the BamHI C promoter itself.
Sung
N S
NS
Department of Microbiology, University of North Carolina, Chapel Hill 27514.
Kenney
S
S
Gutsch
D
D
Pagano
J S
JS
D000956:Antigens, Viral / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000235:genetics* / Q000378:metabolism; D015245:Deoxyribonuclease BamHI / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D019309:Epstein-Barr Virus Nuclear Antigens; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012367:RNA, Viral / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured
D000956:Antigens, Viral; D004279:DNA, Viral; D019309:Epstein-Barr Virus Nuclear Antigens; D012367:RNA, Viral; D015245:Deoxyribonuclease BamHI