IDENTIFICATION OF EPSTEIN-BARR-VIRUS NUCLEAR ANTIGEN-1 PROTEIN DOMAINS THAT DIRECT INTERACTIONS AT A DISTANCE BETWEEN DNA-BOUND PROTEINS

The EBNA1 protein of Epstein-Barr virus (EBV) binds to and activates D NA replication from the EBV latent origin of replication, oriP, via a direct interaction with the two noncontiguous subelements of oriP. The EBNA1 molecules bound to the oriP subelements interact efficiently wi th each other by a DNA looping mechanism. We have previously mapped a region of EBNA1 (termed the looping region) that is required to mediat e the interaction of the EBNA1 molecules bound to the oriP subelements . We now demonstrate that two fragments of this region of EBNA1, which consist largely of an eight amino acid repeat, can mediate homotypic interactions when transferred to another DNA-binding protein. Protein interactions mediated by the EBNA1 looping region appear to be depende nt on DNA binding since these interactions were detected between DNA-b ound forms of the proteins only.