Structural basis of DNA binding by the NAC transcription factor ORE1, a master regulator of plant senescence

Plants use sophisticated mechanisms of gene expression to control senescence in response to environ-mental stress or aging. ORE1 (Arabidopsis thaliana NAC092) is a master regulator of senescence that be-longs to the plant-specific NAC transcription factor protein family. ORE1 has been reported to bind to mul-tiple DNA targets to orchestrate leaf senescence, yet the mechanistic basis for recognition of the cognate gene sequence remains unclear. Here, we report the crystal structure of the ORE1-NAC domain alone and its DNA-binding form. The structure of DNA-bound ORE1-NAC revealed the molecular basis for nucleobase recognition and phosphate backbone interactions. We show that local versatility in the DNA-binding site, in combination with domain flexibility of the ORE-NAC homodimer, is crucial for the maintenance of binding to intrinsically flexible DNA. Our results provide a platform for understanding other plant-specific NAC pro-tein-DNA interactions as well as insight into the structural basis of NAC regulators in plants of agronomic and scientific importance.