K. Shire et al., EBP2, a human protein that interacts with sequences of the Epstein-Barr virus nuclear antigen 1 important for plasmid maintenance, J VIROLOGY, 73(4), 1999, pp. 2587-2595
The replication and stable maintenance of latent Epstein-Barr virus (EBV) D
NA episomes in human cells requires only one viral protein, Epstein-Barr nu
clear antigen 1 (EBNA1). To gain insight into the mechanisms by which EBNA1
functions, we used a yeast two-hybrid screen to detect human proteins that
interact with EBNA1. We describe here the isolation of a protein, EBP2 (EB
NA1 binding protein 2), that specifically interacts with EBNA1. EBP2 was al
so shown to bind to DNA-bound EBNA1 in a one-hybrid system, and the EBP2-EB
NA1 interaction was confirmed by coimmunoprecipitation from insect cells ex
pressing these two proteins. EBP2 is a 35-kDa protein that is conserved in
a variety of organisms and is predicted to form coiled-coil interactions. W
e have mapped the region of EBNA1 that binds EBP2 and generated internal de
letion mutants of EBNA1 that are deficient in EBP2 interactions. Functional
analyses of these EBNA1 mutants show that the ability to bind EBP2 correla
tes with the ability of EBNA1 to support the long-term maintenance in human
cells of a plasmid containing the EBV origin, oriP. An EBNA1 mutant lackin
g amino acids 325 to 376 was defective for EBP2 binding and long-term oriP
plasmid maintenance but supported the transient replication of oriP plasmid
s at wild-type levels. Thus, our results suggest that the EBNA1-EBP2 intera
ction is important for the stable segregation of EBV episomes during cell d
ivision but not for the replication of the episomes.