Biochemical and Biophysical Research Communications, Vol.456, No.1, 207-212, 2015
The pH-sensitive structure of the C-terminal domain of voltage-gated proton channel and the thermodynamic characteristics of Zn2+ binding to this domain
The voltage-gated proton channel Hv1 is strongly sensitive to Zn2+. The H+ conduction is decreased at a high concentration of Zn2+ and Hv1 channel closing is slowed by the internal application of Zn2+. Although the recent studies demonstrated that Zn2+ interacts with the intracellular C-terminal domain, the binding sites and details of the interaction remain unknown. Here, we studied the pH-dependent structural stability of the intracellular C-terminal domain of human Hv1 and showed that Zn2+ binds to His(244) and His(266) residues. The thermodynamics signature of Zn2+ binding to the two sites was investigated by isothermal titration calorimetry. The binding of Zn2+ to His(244) (mutant H266A) and His(266) (mutant H244A) were an endothermic heat reaction and an exothermic heat reaction, respectively. (C) 2014 Elsevier Inc. All rights reserved.