CORRECTION OF THE NMR STRUCTURE OF THE ETS1 DNA COMPLEX/

The ETS family of transcription factors consists of a group of protein s that share a highly conserved 85 amino acid DNA-binding domain (DBD) . This family recognizes a consensus sequence rich in purine bases wit h a central GGAA motif. A comparison of the published three-dimensiona l structures of the DBD/DNA complexes of ETS1 by NMR [Werner et al. (1 995) Cell, 83, 761-771] and the related Pu.l by X-ray crystallography [Kodandapani et al. (1996) Nature, 380, 456-460] reveals an apparent d iscrepancy in which the protein domains bind with opposite polarity to their target sequences. This surprising and highly unlikely result pr ompted us to reexamine our NMR structure. Additional NMR experiments n ow reveal an error in the original interpretation of the spectra defin ing the orientation of the ETS1-DBD on DNA. It was originally reported that the ETS1-DBD bound to DNA with a bipartite motif involving major groove recognition via a helix-turn-helix element and minor groove re cognition via protein side-chain intercalation. The presence of interc alation was deduced on the basis of numerous NOEs between several amin o acids in the protein and a resonance at 12.33 ppm originally assigne d to a DNA imino proton. New NMR experiments now conclusively demonstr ate that this resonance, which is located within the DNA imino proton region of the spectrum, arises from the hydroxyl proton of Tyr(86). Re alization of this error necessitated reanalysis of the intermolecular NOEs. This revealed that the orientation of the ETS1-DBD in he complex is opposite to that originally reported and that a tryptophan residue does not intercalate into the DNA. The calculation of a new ensemble of structures based on the corrected data indicates that the structure of the ETS1-DBD/DNA complex is indeed similar to the X-ray structure of the Pu.l-DBD/DNA complex.