A Novel Model of the Dimeric Human Hv1 Channel Reveals a Putative ATP Binding Site

LLANOS, M; MARTÍN, P; ENRIQUE, N; FELICE, JI; ASUAJE, A; GAVERNET, L; MILESI, V; VENTURA, C

Congreso; 65th Biophysical Society Annual Meeting; 2021

Biophysical Society

A multi-template model of the human voltage-gated proton channel (hHv1) was developed by combining the recently solved NMR structural ensemble of the hHv1 (PDBID: 5OQK) with the coiled-coil C-terminal domain (PDBID: 3A2A), bridging them through the chimeric mHv1cc structure (PDBID: 3WKV). The model was built and refined as a dimer within Rosetta?s Membrane framework, using the symmetry extracted from the coiled-coil and including experimentally derived constraints during the relaxation. The dimericmodel was then subjected to extensive Gaussian Accelerated Molecular Dynamics simulations in a POPC bilayer, and representative snapshots were extracted from the trajectory by clustering analysis. Blind docking simulations of an ATP molecule on this structural ensemble revealed a putative ATP binding site located on the intracellular portion of the permeation pathway, below the hydrophobic gasket. The same region was identified by two sequencebased ATP binding site predictors: ATPSite and ATPint; and a third metapredictor which combines sequence and structure-based features: ATPBind. According to the in-silico predictions, we found that whole-cell hHv1 current measured in presence of intracellular 3 mM ATP (patch-clamp, Jurkat T cells, n=7) showed a higher amplitude (148.3527.0 vs 35.654.6 pA at 20 mV p