HIFs: New arginine mimic inhibitors of the Hv1 channel with improved VSD-ligand interactions

Area of Science:

• Biophysics
• Molecular Pharmacology
• Ion Channel Physiology

Background:

• The human voltage-gated proton channel (Hv1) is crucial for cellular processes and implicated in diseases like cancer and stroke.
• Hv1's voltage-sensing domain facilitates proton transport and NOX enzyme regulation.
• Aromatic guanidine derivatives, like 2-guanidinobenzimidazole (2GBI), inhibit Hv1, but their binding mechanisms require further elucidation.

Purpose of the Study:

• To investigate the role of aromatic interactions in Hv1 inhibition, particularly concerning the F150A mutation's effect on 2GBI binding.
• To design novel Hv1 inhibitors with enhanced affinity by understanding the structural basis of inhibitor-channel interactions.
• To explore new therapeutic strategies targeting Hv1 for various diseases.

Main Methods:

• Electrophysiological recordings to measure channel activity and inhibitor effects.
• Site-directed mutagenesis, including the F150A mutation, to probe residue contributions.
• Nonsense suppression methodology for site-specific incorporation of fluorinated phenylalanines.
• Structure-activity relationship studies for designing new inhibitor compounds.

Main Results:

• The F150A mutation significantly increases the apparent binding affinity of 2GBI, suggesting a binding site rearrangement.
• Aromatic interactions play a key role in the binding of inhibitors to Hv1.
• Newly designed "Hv1 Inhibitor Flexibles" (HIFs) exhibit superior inhibitory properties compared to 2GBI for the wild-type channel.

Conclusions:

• The F150A mutation facilitates inhibitor binding through conformational changes in the Hv1 channel.
• Understanding Hv1 binding site dynamics is critical for developing potent inhibitors.
• HIFs represent a promising new class of high-affinity Hv1 inhibitors with therapeutic potential.