Structure of DNA Binding Domain of Plant Telomere Binding Proteins Represents Unique Features of Telomere Binding Protein Family

Abstract

Telomeres, the ends of linear eukaryotic chromosomes, are composed of short repeats of G-rich sequences and play essential roles in genome stability with various telomere binding proteins. To characterize the binding mode of plant telomere DNA and telomere binding protein, we determined the structures of DNA binding domain and telomere complex of NgTRF1, atTRF and RTBP1, double strand telomere binding proteins of plants, by multidimensional NMR spectroscopy and X-ray crystallography. We have identified the DNA binding interface of the DNA binding domain of TBPs, which is composed of 4 α-helices by means of chemical shift perturbation analysis. The complex crystal structure of NgTRF1561-681 and plant telomere DNA (TTTAGGG)2 have shown the molecular details of the interaction between them and we confirmed the interaction biochemically through site-directed mutagenesis. From the comparison with the structure of human telomere binding protein, we tried to show the unique features of plant telomere binding protein in the mode of telomere DNA binding as well as the similarity with the telomere binding proteins in other organisms. To our knowledge, this is the first report of the complex structure of telomere binding protein and telomere DNA in plant.