THE N-TERMINAL FINGERS OF CHICKEN GATA-2 AND GATA-3 ARE INDEPENDENT SEQUENCE-SPECIFIC DNA-BINDING DOMAINS

The GATA family of vertebrate DNA binding regulatory proteins are expr essed in diverse tissues and at different times of development. Howeve r, the DNA binding regions of these proteins possess considerable homo logy and recognize a rather similar range of DNA sequence motifs. DNA binding is mediated through two domains, each containing a zinc finger . Previous results have led to the conclusion that although in some ca ses the N-terminal finger can contribute to specificity and strength o f binding, it does not bind independently, whereas the C-terminal fing er is both necessary and sufficient for binding, Here we show that alt hough this is true for the N-terminal finger of GATA-1, those of GATA- 2 and GATA-3 are capable of strong independent binding with a preferen ce for the motif GATC. Binding requires the presence of two basic regi ons located on either side of the N-terminal finger. The absence of on e of these near the GATA-1 N-terminal finger probably accounts for its inability to bind. The combination of a single finger and two basic r egions is a new variant of a motif that has been previously found in t he binding domains of other finger proteins. Our results suggest that the DNA binding properties of the N-terminal finger may help distingui sh GATA-2 and GATA-3 from GATA-1 and the other GATA family members in their selective regulatory roles in vivo.