Extended Data Fig. 3: NMR spectra and structural study of Ctc1 OB-A with p50 peptide.

a, Assigned ¹H-¹⁵N HSQC spectrum of ¹⁵N-labelled Ctc1 OB-A (residues 1-183) in the presence of unlabelled p50 peptide (residues 228-250). Inset shows the expanded central region of the spectrum. b, Superimposed ¹H-¹⁵N HSQC spectra of ¹⁵N-labelled Ctc1 OB-A in the presence (yellow) and absence (gray) of unlabelled p50 peptide. Signals from the same residues with chemical shift differences of more than 0.25 ppm are connected by dashed arrows. Signals from residues 68-70 that only appear in the presence of p50 peptide are labelled with asterisks. c, Chemical shift perturbation (CSP) index of ¹⁵N-labelled Ctc1 OB-A upon binding p50 peptide. Magenta box indicates the region that is shown in Fig. 2d. d, Chemical-shift-based secondary-structure score of Ctc1 OB-A in the absence (grey) and presence (yellow) of p50 peptide. The scores are determined using TALOS+ (ref. ⁵⁴). Top and bottom edges of each bar represent the probabilities of each residue assigned to be α helix and β sheet, respectively. The secondary structure of Ctc1 OB-A observed in the cryo-EM structure is shown below for comparison. e, Plot of long range (greater than 5 residues) ¹H-¹H NOE restraints observed within Ctc1 OB-A. Residues with pairwise NOE restraint(s) are connected by a link. Links are colour coded as indicated based on the number of NOE restraints between the two connected residues.