Fig 1.

The DNA-binding domain of Ndt80 has a previously uncharacterized structure. (A) A representative region of the experimental electron density map is shown contoured at 1.8 σ with the model in the form I lattice. (B) A topological diagram of the DNA-binding domain of Ndt80 reveals a distinct fold comprising 19 β-strands, three short α-helices, and two 3₁₀ helices. The central core is a β-sandwich comprising eight antiparallel β-strands. (C) The structure is shown here as a stereo ribbon rendering with the conserved β core in green. An additional structural feature (shown in blue), which we refer to as “florets,” contains two helix-loop regions held in place by two antiparallel β-strands. The proposed DNA-binding regions of the structure are highlighted in red.