Fig. 1
Experimental NMR and EM data of the 468 kDa TET2 assembly. a MAS NMR and b solution-NMR spectra of TET2, showing high resolution despite the large subunit size. c Experimental 4.1 Å resolution cryo-EM electron-density map. d Secondary structure of TET2, derived from MAS NMR resonance assignments and the TALOS-N software20, shown as a function of the residue number. Residues shown with shorter bars were not assigned, and the secondary structure assignment results from a database approach in TALOS-N. e Experimentally detected intra-subunit long-range distance restraints from solution-NMR and MAS NMR, displayed through lines connecting residues in close spatial proximity. Note that part of these distance restraints were spectrally ambiguous, i.e., could be assigned to several atom-atom pairs, and was rendered unambiguous throughout the structure calculation approach (displayed in red). See Table 1 for restraints statistics. All NMR experiments performed in this study and acquisition parameters are listed in Supplementary Tables 2–5. f α-Helices detected by the helixhunter2 software25,50 in the EM map truncated to 8 Å resolution. Symmetry-related α-helices are shown in equal colors. Additional β-sheet parts, automatically detected by gorgon51 are shown in Supplementary Fig. 8A. g Zoom on one subunit, identified by a clustering analysis (Supplementary Fig. 8). The five longest α-helices, used for the initial structure calculation steps are labeled with A to E in order of decreasing length (see Table 1)
