Study of the conformational dynamics of Helicobacter pylori CtpA

Bacterial carboxyl-terminal processing proteases (CTPs) are critical for maintaining protein quality control, mediating signal transduction, and enabling cellular adaptation. Their activation typically involves substrate binding to the PDZ domain or interaction with an adaptor protein. In this study, we employed hydrogen–deuterium exchange mass spectrometry (HDX-MS) to investigate the conformational dynamics of the CTP from Helicobacter pylori, CtpA, in both the presence and absence of its substrate HP1076. To eliminate the confounding effects of proteolysis, a triple mutant (CtpATM) with an inactivated catalytic triad was used. Additionally, a hinge-region mutant (CtpAF105R) was employed to validate the dynamic behavior of the linker connecting the PDZ domain. This study reveals CtpA transitions between resting and active states independently of substrate binding.