FIGURE 5.

Analysis of EcDsbA-SigA peptide interaction by NMR spectroscopy. a, EcDsbA residues for which chemical shift perturbations are observed upon the addition of the peptide are colored in magenta on the crystal structure of the EcDsbA-peptide complex (Protein Data Bank code 3DKS, chain C; the peptide 3DKS, chain E, is in orange stick format). His³², which is not observed in either HSQC spectrum is colored in cyan. A continuous surface is formed by residues that form the EcDsbA-peptide interface in the crystal. b, ¹⁵N HSQC spectrum of EcDsbA in the absence (magenta) and presence (cyan) of SigA peptide. The expansion demonstrates perturbations that are observed for some residues (e.g. Phe²⁹ and Cys³³), whereas other residues (e.g. Gly⁶ and Asp⁸⁶) are unaffected.