Scorpion toxin inhibits the voltage‐gated proton channel using a Zn2+‐like long‐range conformational coupling mechanism. (3rd March 2020)

• Record Type: Journal Article
• Authors: Tang, Dongfang; Yang, Yuqin; Xiao, Zhen; Xu, Jiahui; Yang, Qiuchu; Dai, Han; Liang, Songping; Tang, Cheng; Dong, Hao; Liu, Zhonghua
• Is Part Of: British journal of pharmacology. Volume 177:Number 10(2020)
• Page Start: 2351
• Page End: 2364
• Publication Date: 2020-03-03
• Subjects: Pharmacology -- Periodicals; Chemotherapy -- Periodicals; Drug Therapy -- Periodicals; Pharmacology -- Periodicals; 615.1
• DOI: 10.1111/bph.14984
• Languages: English
• ISSNs: 0007-1188

Abstract

Abstract : Background and Purpose: Blocking the voltage‐gated proton channel HV 1 is a promising strategy for the treatment of diseases like ischaemia stroke and cancer. However, few HV 1 channel antagonists have been reported. Here, we have identified a novel HV 1 channel antagonist from scorpion venom and have elucidated its action mechanism. Experimental Approach: HV 1 and NaV channels were heterologously expressed in mammalian cell lines and their currents recorded using whole‐cell patch clamp. Site‐directed mutagenesis was used to generate mutants. Toxins were recombinantly produced in Escherichia coli. AGAP/W38F‐HV 1 interaction was modelled by molecular dynamics simulations. Key Results: The scorpion toxin AGAP (anti‐tumour analgesic peptide) potently inhibited HV 1 currents. One AGAP mutant has reduced NaV channel activity but intact HV 1 activity (AGAP/W38F). AGAP/W38F inhibited HV 1 channel activation by trapping its S4 voltage sensor in a deactivated state and inhibited HV 1 currents with less pH dependence than Zn 2+ . Mutation analysis showed that the binding pockets of AGAP/W38F and Zn 2+ in HV 1 channel partly overlapped (common sites are His140 and His193). The E153A mutation at the intracellular Coulombic network (ICN) in HV 1 channel markedly reduced AGAP/W38F inhibition, as observed for Zn 2+ . Experimental data and MD simulations suggested that AGAP/W38F inhibited HV 1 channel using a Zn 2+ ‐like long‐range conformational coupling mechanism. Conclusion and Implications: Our results suggest that the Zn 2+ binding pocket in HV 1 channel might be a hotspot for modulators and valuable for designing HV 1 channel ligands. Moreover, AGAP/W38F is a useful molecular probe to study HV 1 channel and a lead compound for drug development.