Figure 6. ¹H-¹⁵N HSQC spectra of HasB_CTD wild type (A), HasBR38A (B) and HasBR38E (C) in the presence (blue) or absence (black) of the TonB box peptide.

Some of the residues experiencing chemical shift perturbation upon peptide binding in HasB_CTD wild type (A) and HasBR38A (B) are circled with dashed lines. The equivalent residues are indicated for HasBR38E (C) with no chemical shift changes.