Solution structure of the major DNA-binding domain of Arabidopsis thaliana ethylene-insensitive3-like3

Ethylene-insensitive3 (EIN3) and EIN3-like (EIL) proteins are essential transcription factors in the ethylene signaling of higher plants. The ElN3/ElL proteins bind to the promoter regions of the downstream genes and regulate their expression. The location of the DNA-binding domain (DBD) in the primary structure was unclear, since the proteins show no sequence similarity to other known DBDs. Here, we identify the major DBD of an ElN3/ElL protein, Arabidopsis thaliana ElL3, containing a key mutational site for DNA binding and signaling (ein3-3 site), and determine its solution structure by NMR spectroscopy The structure consists of five g.-helices, possessing a novel fold dissimilar to known DBD structures. By a chemical-shift perturbation analysis, a region including the ein3-3 site is suggested to be involved in DNA binding. (c) 2005 Elsevier Ltd. All rights reserved.