FIG. 1.

EBNA1 binding sites at DS of oriP and mutations that alter their spacing. (A) EBNA1 dimers (double spheres) bound to their four sites at the ∼120-bp replicator DS. Distances between the centers of the binding sites and some restriction sites are indicated. (B) Nucleotide sequences between the active pairs of EBNA1 sites 3 and 4 and 1 and 2 for wild-type (WT) and mutants, with the outermost two nucleotides of each EBNA1 site underlined. The boundaries of the 16-bp palindromic EBNA1 binding site were determined in a study of synthetic sites and from crystallographic data (3, 5). Substituted or inserted nucleotides are in bold; dots indicate deleted nucleotides.