Fig. 2. HSP90α-NTD samples two states in solution.

a 2D-strips extracted from ¹³CH₃-edited 3D NOESY, at ¹³C frequencies of M130, I131 and L29 methyl groups of WT-HSP90α-NTD. The 3D HMQC-NOESY-HMQC experiment was acquired at 25 °C on a spectrometer operating at a ¹H frequency of 950 MHz. b Representation on a 3D structure of HSP90α-NTD (PDB 1YES) of examples of intermethyl NOEs involving M130 and I131 with methyl groups distant by more than 30 Å. c Representatives two states of HSP90α-NTD calculated simultaneously⁷⁴ to satisfy all NMR restraints acquired on WT-HSP90α-NTD. Boxes correspond to zooms on structure displaying interactions stabilizing the conformation of the ATP-lid either in closed (orange) or open conformation (blue) d Variation of average CYANA target function for the 20 best structures according to the number of states used to calculate each conformer. e Table summarizing intensity increases (+), decreases (−), or disappearance (Ø) of characteristic NOEs corresponding to HSP90α-NTD ATP-lid open and closed states (Supplementary Table 2).