Sequence and functional analysis of EBNA-LP and EBNA2 proteins from nonhuman primate lymphocryptoviruses.
The Epstein-Barr virus (EBV) EBNA-LP and EBNA2 proteins are the first to be synthesized during establishment of latent infection in B lymphocytes. EBNA2 is a key transcriptional regulator of both viral and cellular gene expression and is essential for EBV-induced immortalization of B lymphocytes. EBNA-LP is also important for EBV-induced immortalization of B lymphocytes, but far less is known about the functional domains and cellular cofactors that mediate EBNA-LP function. While recent studies suggest that serine phosphorylation of EBNA-LP and coactivation of EBNA2-mediated transactivation are important, more detailed mutational and genetic studies are complicated by the repeat regions that comprise the majority of the EBNA-LP sequence. Therefore, we have used a comparative approach by studying the EBNA-LP homologues from baboon and rhesus macaque lymphocryptoviruses (LCVs) (baboon LCV and rhesus LCV). The predicted baboon and rhesus LCV EBNA-LP amino acid sequences are 61 and 64% identical to the EBV EBNA-LP W1 and W2 exons and 51% identical to the EBV EBNA-LP Y1 and Y2 exons. Five evolutionarily conserved regions can be defined, and four of eight potential serine residues are conserved among all three EBNA-LPs. The major internal repeat sequence also revealed a highly conserved Wp EBNA promoter with strong conservation of upstream activating sequences important for Wp transcriptional regulation. To test whether transcriptional coactivating properties were common to the rhesus LCV EBNA-LP, a rhesus LCV EBNA2 homologue was cloned and expressed. The rhesus LCV EBNA2 transcriptionally transactivates EBNA2-responsive promoters through a CBF1-dependent mechanism. The rhesus LCV EBNA-LP was able to further enhance rhesus LCV or EBV EBNA2 transactivation 5- to 12-fold. Thus, there is strong structural and functional conservation among the simian EBNA-LP homologues. Identification of evolutionarily conserved serine residues and regions in EBNA-LP homologues provides important clues for identifying the cellular cofactors and molecular mechanisms mediating these conserved viral functions.
Peng
R
R
Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030, USA.
Gordadze
A V
AV
Fuentes Pananá
E M
EM
Wang
F
F
Zong
J
J
Hayward
G S
GS
Tan
J
J
Ling
P D
PD
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D019309:Epstein-Barr Virus Nuclear Antigens; D018143:Lymphocryptovirus / Q000235:genetics* / Q000302:isolation & purification; D008253:Macaca mulatta / Q000821:virology; D008969:Molecular Sequence Data; D010215:Papio / Q000821:virology; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology
D018076:DNA, Complementary; C402641:EBNA-2 protein, Human herpesvirus 4; C402640:EBNA-LP protein, Human herpesvirus 4; D019309:Epstein-Barr Virus Nuclear Antigens; D014764:Viral Proteins