FIGURE 2.

Chemical shift titration experiments of MalE and MalF-P2 in the presence and absence of maltose. A, resonance-specific ¹H-¹⁵N chemical shift changes upon titration of MalF-P2 to U-¹⁵N,²H MalE, in the presence (black) and absence (red) of maltose. Two distinct binding regions in the N-terminal domain of MalE are observed. These regions match the contacts seen in the crystal structure of MalFGK₂-E (PDB ID code 2R6G) (6). MalE and MalF-P2 contacts (with Δ(N, C, O) <5 Å) in the MalFGK₂-E crystal structure are highlighted in gray on the primary sequence (top). In addition, small chemical shift changes are observed for residues not directly involved in the interaction. B, ¹H,¹⁵N correlation spectra for selected residues, not located in the binding interface. Resonances are color coded, MalE (black), MalE/maltose (blue), and MalE/MalF-P2/maltose (red). Chemical shift analysis shows resonances distinct from the maltose-bound and maltose-free MalE, implying that MalE in the presence of MalF-P2 adopts a different conformation.