Interaction of murine ets-1 with GGA-binding sites establishes the ETS domain as a new DNA-binding motif

Abstract

The proto-oncogene ets-1 is the founding member of a new family of eukaryotic transcriptional regulators. Using deletion mutants of murine ets-1 cDNA expressed in Escherichia coli, we show that the DNA-binding domain corresponds closely to the ETS domain, an 85-amino-acid region that is conserved among ets family members. To investigate the specificity of DNA binding of the ETS domain, we mapped the DNA contacts of a monomeric Ets-1 fragment by chemical protection and interference assays. DNA backbone interactions span a 20-nucleotide region and are localized on one face of the helix. Close phosphate and base contacts are restricted to 10 central nucleotides. Contacts map to the major groove in the center of the site. Flanking minor groove interactions also are predicted. To determine the sequence preference in the close contact zone, we selected a pool of high-affinity binding sites using a purified Ets-1 carboxy-terminal fragment. Our Ets-1-selected consensus, 5'-A/GCCGGAA/TGT/C-3', differs from the binding consensus for the Drosophila ETS domain protein E74A, suggesting that specificity of action of ets family members is mediated by the ETS domain. Compared to other well-characterized classes of DNA-binding proteins, Ets-1 produces a unique pattern of DNA contacts. These studies demonstrate that the ETS domain proteins bind DNA in a novel manner.