A protein target site in an early replicated human DNA sequence: a highly conserved binding motif.

We have previously reported that a human nuclear factor, probably corresponding to the USF/MLTF protein [1,2], is able to bind specifically to a DNA sequence present in DNA replicated at the onset of S-phase [3]. Here we demonstrate that the same factor binds also to several other similar sequences, present in eukaryotic and viral genomes. Mutations or methylation in a CpG dinucleotide, central in the palindromic binding site, completely abolish binding. Furthermore, we present evidence for the existence of at least two other nuclear proteins in human cells with the same DNA binding specificity. The data presented suggest a strong evolutionary conservation, among distantly related organisms, of the binding motif, which is probably the target of a number of nuclear factors that share the same DNA binding specificity albeit in the context of different functions.