Employing NaChBac for cryo-EM analysis of toxin action on voltage-gated Na + channels in nanodisc

Significance NaChBac was the first bacterial Nav channel to be characterized and has been a prototype in the study of the structure–function relationship of Nav and Cav channels. Despite advances in the structural biology of prokaryotic and eukaryotic Nav channels, the structure of NaChBac had not been determined. Here we present single particle electron cryomicroscopy (cryo-EM) structures of NaChBac in detergent micelles and in nanodiscs, which exhibit identical conformation. NaChBac can be engineered to be a surrogate to study the interactions between gating modifier toxins (GMTs) and targeted segments on eukaryotic Nav channels. Our comparative structural characterizations emphasize the significance of the membrane environment in the structural study of Nav channels and GMTs.