Figure 11. Allosteric protein responses at key sites seen only at room temperature (RT).

Although the fragment binds in a similar manner and in the same allosteric site (the 197 site) in both the RT model (z0032) (red) and the cryogenic (cryo) model (y1763) (blue), the protein response is different between the two temperatures. At cryo, the protein retains the default open conformation, with loop 16 in the L16 site open and the WPD loop also open. Alternatively, at RT, the L16 site is fully closed, while the WPD loop exhibits alternate conformations with the loop both open and closed. The α7 helix (not shown) remains disordered in both temperatures.

Figure 11—figure supplement 1. Electron density evidence for allosteric protein responses at key sites seen only at room temperature (RT).

(A) Same as main Figure 11. (B) z0032 (red), y1763 (blue), RT density, 1.5 σ, indicate the fragment binds in the 197 site. (C) RT density, 1.5 σ, showing the WPD loop adopts alternative conformations with the WPD loop open and closed. (D) RT density, 1.5 σ, is consistent with loop 16 modeled in the closed conformation.

Figure 11—figure supplement 2. Covalent allosteric inhibitor matches fragment with allosteric response at room temperature (RT).

Overlay of z0032 with PDB ID 6b95, which includes a covalent inhibitor targeting the K197C mutation in the allosteric 197 site. Same coloring as in Figure 9.