Fig. 4

Structure of the TET2 dodecamer from EM/NMR. a Overall view of the dodecamer, highlighting in color one out of the 12 modeled subunits, obtained from joint refinement of 12 subunits against NMR and EM data. b Bundle of 10 structures of one monomer, with an accuracy of 0.7 Å (backbone RMSD relative to crystal structure). The loop region, residues 120–138, which has not been modeled in the crystal structure (PDB 1y0r) is encircled in (b), and shown in the view of the interior of the cavity (c) and as a zoom (d). The EM map around the loop region, seen by cryo-EM (d) is of significantly higher intensity than in the 100 K crystal structure (1y0r). The backbone structure in both panels is from the present NMR/EM study. e, f Results of NMR/EM structure calculation using only EM data truncated to 6 or 8 Å resolution, resulting in backbone RMSD to the crystal structure of 1.8 and 2.6 Å, respectively. The inserts above the structures in (b, e, f) represent typical α-helical densities at the respective resolution levels