Characterization of DP103, a novel DEAD box protein that binds to the Epstein-Barr virus nuclear proteins EBNA2 and EBNA3C

The Epstein-Barr virus-encoded nuclear antigens EBNA2 and EBNA3C both inter act with the cellular transcription factor RBP-JK and modulate the expressi on of several shared target genes, suggesting a tight cooperation in latent ly infected cells. In a survey for additional cellular factors that bind to EBNA2 as well as EBNA3C, we have isolated and characterized DP1031 a novel human member of the DEAD box family of putative ATP-dependent RNA helicase s, The interaction with DP103 is mediated by amino acids (aa) 121-213 of EB NA2 and aa 534-778 of EBNA3C, regions that are not involved in binding of t he viral proteins to RBP-JK, The DP103-cDNA encodes a protein of 824 aa tha t harbors all of the common DEAD box motifs, Monoclonal antibodies raised a gainst DP103 detect a protein of 103 kDa in mammalian cells that resides in high molecular weight complexes in vivo. We have detected an ATPase activi ty intrinsic to or closely associated with DP103, By subcellular fractionat ion, we find DP103 in both a soluble nuclear fraction as well as in the ins oluble skeletal fraction. Whereas the protein and its mRNA are uniformly ex pressed in all tested cell lines, we observed differential expression of th e mRNA. in normal human tissues.