The EBNA-2 arginine-glycine domain is critical but not essential for B-lymphocyte growth transformation; the rest of region 3 lacks essential interactive domains.
Since deletion of region 3 (amino acids [aa] 333 to 425) of Epstein-Barr virus nuclear protein 2 (EBNA-2) results in EBV recombinants which cannot transform primary B lymphocytes (J. I. Cohen, F. Wang, and E. Kieff, J. Virol. 65:2545-2554, 1991), the role of domains of region 3 was investigated. Deletion of the Arg-Gly repeat domain, R-337GQSRGRGRGRGRGRGKG354, results in EBV recombinants that transform primary B lymphocytes with modestly decreased activity. The transformed cells grow slowly and are difficult to expand. EBNA-2 deleted for the Arg-Gly domain does not associate with the nuclear chromatin fraction. The Arg-Gly repeat has an intrinsic ability to bind to histone H1, to other proteins, including EBNA-1, and to nucleic acids, especially poly(G). Two independent deletions of each part of the rest of region 3 (aa 359 to 383 and 385 to 430) have little effect on transformation, while deletion of the rest of region 3 (aa 361 to 425) as a single segment substantially reduces transformation efficiency. EBNA-2 deleted for all of region 3 can still transactivate the LMP1 promoter in transient expression assays but is less active than EBNA-2 in transactivating the BamHI-C promoter. EBNA-2 deleted for the Arg-Gly domain is better than EBNA-2 at transactivating the LMP1 promoter and is as active as EBNA-2 in transactivating the BamHI-C promoter. These data are most compatible with a model in which the Arg-Gly domain of region 3 is a modulator of EBNA-2 interactions and activities, while the rest of region 3 is important in positioning the region 2 J kappa binding domain relative to the region 4 acidic transactivating domain. Despite the null phenotype of the region 3 deletion, region 3 is unlikely to mediate essential interactions with other proteins.
Tong
X
X
Department of Microbiology and Molecular Genetics, Harvard University, Boston, Massachusetts 02115.
Yalamanchili
R
R
Harada
S
S
Kieff
E
E
D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D001120:Arginine; D001483:Base Sequence; D001665:Binding Sites; D002051:Burkitt Lymphoma; D002460:Cell Line; D002467:Cell Nucleus / Q000276:immunology / Q000378:metabolism; D002472:Cell Transformation, Viral; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D003360:Cosmids; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D019309:Epstein-Barr Virus Nuclear Antigens; D005982:Glutathione Transferase / Q000096:biosynthesis; D005998:Glycine; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000276:immunology; D006801:Humans; D016393:Lymphoma, B-Cell; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D017384:Sequence Deletion; D014162:Transfection; D014407:Tumor Cells, Cultured
D000956:Antigens, Viral; D017931:DNA Primers; D004268:DNA-Binding Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; D011993:Recombinant Fusion Proteins; D001120:Arginine; D015500:Chloramphenicol O-Acetyltransferase; D005982:Glutathione Transferase; D005998:Glycine