title: The pH-sensitive structure of the C-terminal domain of voltage-gated proton channel and the thermodynamic characteristics of Zn²⁺ binding to this domain.
abstract: The voltage-gated proton channel Hv1 is strongly sensitive to Zn(2+). The H(+) conduction is decreased at a high concentration of Zn(2+) and Hv1 channel closing is slowed by the internal application of Zn(2+). Although the recent studies demonstrated that Zn(2+) 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 Zn(2+) binds to His(244) and His(266) residues. The thermodynamics signature of Zn(2+) binding to the two sites was investigated by isothermal titration calorimetry. The binding of Zn(2+) to His(244) (mutant H266A) and His(266) (mutant H244A) were an endothermic heat reaction and an exothermic heat reaction, respectively.
authors.affiliation: Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, PR China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, PR China.
authors.forename: Chuanyong
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, PR China. Electronic address: shujieli@nankai.edu.cn.
authors.forename: Shu Jie
authors.initials: SJ
authors.lastname: Li
mesh_terms: D001665:Binding Sites; D002151:Calorimetry; D002942:Circular Dichroism; D006639:Histidine / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry* / Q000502:physiology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011522:Protons; D013696:Temperature; D013816:Thermodynamics; D015032:Zinc / Q000737:chemistry*
chemical_list: C510235:HVCN1 protein, human; D007473:Ion Channels; D011522:Protons; D006639:Histidine; D015032:Zinc
keywords: Carboxyl-terminal domain; Isothermal titration calorimetry (ITC); Voltage-gated proton channel Hv1; Zn(2+)-binding; pH