Fig. 7: Ca2+ stabilizes the global fold of RBD1.
From: Pore formation by the CDTb component of the Clostridioides difficile binary toxin is Ca2+-dependent
A X-ray crystal structure of Ca2+-bound RBD1WT (residues 616-748; 2.3 Å; PDB = 9MUI) with β-sheets 1–10, and N and C-termini labeled. The inset shows backbone and sidechain atoms of residues in the Ca2+-binding site of RBD1WT. Ca2+ is represented by a green sphere. B CD spectra of RBD1WT without Ca2+ (black), in the presence of Ca2+ (2.4 mM; red, 10 mM; blue), and in 8 M urea (without Ca2+; gray, with 2.4 mM Ca2+; dark gray). C CD spectra of RBD1D623A/D734A without Ca2+ (black) and in the presence of Ca2+ (2.4 mM, red; 10 mM, blue), and 8 M urea (without Ca2+; gray, 2.4 mM Ca2+; dark gray). All CD experiments were performed in triplicate (n = 3).
