Extended Data Fig. 5: Influence of Ap4A and ATP on conformational flexibility of BsIMPDH CBS domains by hydrogen/deuterium exchange mass spectrometry.
From: Diadenosine tetraphosphate regulates biosynthesis of GTP in Bacillus subtilis
a. Difference in hydrogen/deuterium exchange (HDX) of representative peptides in the presence of Ap4A (top) or ATP (bottom), expressed as the difference in HDX of ligand-bound BsIMPDH versus its apo-state. b. Location of selected peptides exhibiting bimodality in HDX (EX1 kinetics) displayed on the adjacent CBS domains of two monomers of Ap4A-bound BsIMPDH. c-d. Mass spectra of two selected BsIMPDH peptides exhibiting EX1 kinetics for hydrogen/deuterium exchange, that is, c. the peptides containing residues 113–136, and d. residues 172–200 of BsIMPDH. The occurrence of a fast-exchanging population in the apo-state (red) is indicative for unfolding of secondary structures, which is restricted in samples of Ap4A-bound (blue) and ATP-bound (green) BsIMPDH.
