The N-terminal fingers of chicken GATA-2 and GATA-3 are independent sequence-specific DNA binding domains

Abstract

The GATA family of vertebrate DNA binding regulatory proteins are expressed in diverse tissues and at different times of development. However, the DNA binding regions of these proteins possess considerable homology 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 cases the N‐terminal finger can contribute to specificity and strength of binding, it does not bind independently, whereas the C‐terminal finger is both necessary and sufficient for binding. Here we show that although 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 preference for the motif GATC. Binding requires the presence of two basic regions located on either side of the N‐terminal finger. The absence of one 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 regions is a new variant of a motif that has been previously found in the binding domains of other finger proteins. Our results suggest that the DNA binding properties of the N‐terminal finger may help distinguish GATA–2 and GATA‐3 from GATA‐1 and the other GATA family members in their selective regulatory roles in vivo.

The GATA site-dependent hemogen promoter is transcriptionally regulated by GATA1 in hematopoietic and leukemia cells

“…For instance, the N-terminal zinc fingers of GATA1, GATA2 and GATA3 recognize different DNA motifs and may contribute to their selectivity in binding target DNA sites. 26 Extensive studies using both in vitro and in vivo models demonstrate that the functions and downstream targets of GATA1 overlap with those of GATA2. 25,27,28 Moreover, in GATA1 knockout mice, GATA2 is upregulated to partially compensate for the loss of GATA1, and both GATA1 and GATA2 are critical for initiation of blood formation.…”

GATA Switches as Developmental Drivers

“…The C-terminal finger mediates sequence-specific DNA binding (24 -26), whereas the N-terminal finger modulates DNA binding and contacts DNA with sequence specificity in certain contexts ( Fig. 2) (24,27,28). The zinc fingers interact with multiple coregulators, which are discussed below.…”

Determinants of GATA-1 Binding to DNA

“…These data differ from site selection experiments on the fulllength cGATA-2 where a distinct preference for AGATAA and AGATCT is reported (13), reflecting the binding properties of the C-terminal finger of GATA-2. Binding studies on the Nterminal finger of GATA-2 have shown that this peptide has a preference for the GATC motif, binding with a K d of 5 nM to AGATCT and a K d of 28 nM to AGATAA (10). Even though this difference in affinity is reflected partially in the selection experiments, in which AGATC is selected over AGATA in a 2.2:1 ratio (data not shown), an AGATCT site is not exclusively selected.…”

“…Published results have indicated that the N-terminal zinc finger of cGATA-2 binds to DNA with nanomolar affinities (10), suggesting that selection experiments with this peptide were feasible. However, unlike GATA-2, the N-terminal zinc finger of GATA-1 does not bind with high affinity to DNA (8,9).…”

“…1, peptides CC11 and NN4, respectively), the N-terminal finger does not recognize the AGATAA consensus motif, indicating that the flanking or poorly conserved linker residues may play a key role in DNA recognition. A role for the flanking residues has been pointed out in the case of the N-terminal finger of GATA-2 (10). Like the N-terminal finger of GATA-1, this homologous finger shows a binding preference for GATC motifs.…”