Characterization of the DNA-binding properties of the myeloid zinc finger protein MZF1: two independent DNA-binding domains recognize two DNA consensus sequences with a common G-rich core

Abstract

The myeloid zinc finger gene 1, MZF1, encodes a transcription factor which is expressed in hematopoietic progenitor cells that are committed to myeloid lineage differentiation. MZF1 contains 13 C2H2 zinc fingers arranged in two domains which are separated by a short glycine- and proline-rich sequence. The first domain consists of zinc fingers 1 to 4, and the second domain is formed by zinc fingers 5 to 13. We have determined that both sets of zinc finger domains bind DNA. Purified, recombinant MZF1 proteins containing either the first set of zinc fingers or the second set were prepared and used to affinity select DNA sequences from a library of degenerate oligonucleotides by using successive rounds of gel shift followed by PCR amplification. Surprisingly, both DNA-binding domains of MZF1 selected similar DNA-binding consensus sequences containing a core of four or five guanine residues, reminiscent of an NF-kappa B half-site: 1-4, 5'-AGTGGGGA-3'; 5-13, 5'-CGGGnGAGGGGGAA-3'. The full-length MZF1 protein containing both sets of zinc finger DNA-binding domains recognizes synthetic oligonucleotides containing either the 1-4 or 5-13 consensus binding sites in gel shift assays. Thus, we have identified the core DNA consensus binding sites for each of the two DNA-binding domains of a myeloid-specific zinc finger transcription factor. Identification of these DNA-binding sites will allow us to identify target genes regulated by MZF1 and to assess the role of MZF1 as a transcriptional regulator of hematopoiesis.