A NOVEL MODE OF DNA RECOGNITION BY A BETA-SHEET REVEALED BY THE SOLUTION STRUCTURE OF THE GCC-BOX BINDING DOMAIN IN COMPLEX WITH DNA

The 3D solution structure of the GCC-box binding domain of a protein f rom Arabidopsis thaliana in complex with its target DNA fragment has b een determined by heteronuclear multidimensional NMR in combination wi th simulated annealing and restrained molecular dynamic calculation. T he domain consists of a three-stranded anti-parallel beta-sheet and an a-helix packed approximately parallel to the beta-sheet. Arginine and tryptophan residues in the beta-sheet are identified to contact eight of the nine consecutive base pairs in the major groove, and at the sa me time bind to the sugar phosphate backbones, The target DNA bends sl ightly at the central CG step, thereby allowing the DNA to follow the curvature of the beta-sheet.