Recognition Mechanism of a Novel Gabapentinoid Drug, Mirogabalin, for Recombinant Human a2d1, a Voltage-Gated Calcium Channel Subunit

Mirogabalin is a novel gabapentinoid drug with a hydrophobic bicyclo substituent on the y-aminobutyric acid moiety that targets the voltage-gated calcium channel subunit ot,281. Here, to reveal the mirogabalin recognition mechanisms of ot,281, we present structures of recombinant human ot,281 with and without mirogabalin analyzed by cryo-electron microscopy. These structures show the binding of mirogabalin to the previously reported gabapentinoid binding site, which is the extracellular dCache_1 domain containing a conserved amino acid binding motif. A slight conformational change occurs around the residues posi-tioned close to the hydrophobic group of mirogabalin. Mutagenesis binding assays identified that residues in the hydrophobic interaction region, in addition to several amino acid binding motif residues around the amino and carboxyl groups of mirogabalin, are critical for mirogabalin binding. The A215L mutation intro-duced to decrease the hydrophobic pocket volume predictably suppressed mirogabalin binding and pro-moted the binding of another ligand, L-Leu, with a smaller hydrophobic substituent than mirogabalin. Alterations of residues in the hydrophobic interaction region of ot,281 to those of the ot,282, ot,283, and ot,284 isoforms, of which ot,283 and ot,284 are gabapentin-insensitive, suppressed the binding of mirogabalin. These results support the importance of hydrophobic interactions in ot,281 ligand recognition.(c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecom-mons.org/licenses/by/4.0/).

Automated summary

In this study, the researchers used cryo-electron microscopy to reveal the binding mechanisms of mirogabalin to ot,281. They found that mirogabalin binds to the reported gabapentinoid binding site and causes slight conformational changes near its hydrophobic group. Mutagenesis binding assays identified critical residues for mirogabalin binding and altering the hydrophobic interaction region suppressed mirogabalin binding. These findings highlight the importance of hydrophobic interactions in ligand recognition by ot,281.