TRANSCRIPTIONAL ACTIVATION AND DNA-BINDING BY THE ERYTHROID FACTOR GF-1/NF-E1/ERYF-1

The murine, erythroid DNA-binding protein GF-1 (also known as NF-E1, Eryf 1), a 413-amino acid polypeptide with two novel finger domains of the C(x)-C(x) variety, recognizes a consensus GATA motif present in cis elements of the majority of erythroid-expressed genes. We have performed a structure-function analysis of this protein to evaluate its potential as a transcriptional activator and to examine the role of the finger domains in DNA binding. Using a cotransfection assay, we find that GF-1 is a potent transcriptional activator with several activation domains but that this is revealed only in heterologous cells and with reporters containing minimal promoters onto which either a single or multiple GATA-binding sites are placed. The two fingers of GF-1 are functionally distinct and cooperate to achieve specific, stable DNA binding. The amino finger is necessary only for full specificity and stability of binding, whereas the carboxyl finger is required for binding. The role of each finger is more pronounced with some GATA-binding sites than with others, suggesting a diversity of interactions between GF-1 and different target sites. The complex activation and DNA-binding properties of GF-1 are likely to contribute to the ability of this single protein to participate widely in gene expression throughout erythroid development.