Crystal structure of a voltage-gated sodium channel in two potentially inactivated states

Abstract

In excitable cells, voltage-gated sodium (NaV) channels activate to initiate action potentials and then undergo fast and slow inactivation processes that terminate their ionic conductance1,2. Inactivation is a hallmark of NaV channel function and is critical for control of membrane excitability3, but the structural basis for this process has remained elusive. Here we report crystallographic snapshots of the wild-type NavAb channel from Arcobacter butzleri captured in two potentially inactivated states at 3.2 Å resolution. Compared to previous structures of NavAb S6-cysteine mutants4, the pore-lining S6 helices and the intracellular activation gate have undergone significant rearrangements in which one pair of S6 segments has collapsed toward the central pore axis and the other S6 pair has moved outward to produce a striking dimer-of-dimers configuration. An increase in global structural asymmetry is observed throughout our wild-type NavAb models, reshaping the ion selectivity filter at the extracellular end of the pore, the central cavity and its residues analogous to the mammalian drug receptor site, and the lateral pore fenestrations. The voltage-sensing domains also shift around the perimeter of the pore module in NavAb, and local structural changes identify a conserved interaction network that connects distant molecular determinants involved in NaV channel gating and inactivation. These potential inactivated-state structures provide new insights into NaV channel gating and novel avenues to drug development and therapy for a range of debilitating NaV channelopathies.

Molecular basis of ion permeability in a voltage‐gated sodium channel

“…The structures of several prokaryotic sodium channels in different functional states (Payandeh et al , 2011, 2012; McCusker et al , 2012; Zhang et al , 2012; Bagnéris et al , 2013, 2014, 2015; Tsai et al , 2013; Shaya et al , 2014) have been solved by X‐ray crystallography or electron microscopy. Functional studies on wild‐type and mutant prokaryotic channels (Ren et al , 2001; Yue et al , 2002; McCusker et al , 2011; Shaya et al , 2011; Tang et al , 2014) have suggested which regions and residues may be important for ion binding, selectivity and translocation within the SF.…”

The conformational shifts of the voltage sensing domains between NavRh and NavAb

“…Na v Rh was suggested to be captured in an inactivated conformation [4], whereas Na v Ab was reported to reflect a "pre-open" conformation [3]. Two extra crystal structures of Na v Ab were published to be in inactivated states [12]. Nevertheless, the structural comparisons discussed here can be applied to the new Na v Ab structures, because the latter two can be superimposed to the first Na v Ab structure with rmsd values of 1.6 and 1.…”

Adsorption of charged protein residues on an inorganic nanosheet: Computer simulation of LDH interaction with ion channel

“…A bacterial voltage gated sodium channel Na V Ab embedded into a POPC lipid bilayer was chosen for the model, since their all-atom structure is well-studied [17,18]. The presence of the hosted POPC bilayer provides a suitable environment for the membrane protein.…”

“…The Na V Ab voltage-gated sodium channel was chosen for the model, whose atom-level structure is well-known. All-atom structural data [17,18] were used. To provide more realistic simulation the sodium channel was embedded into a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC) bilayer consisting of 559 lipids in a water environment with Cl -and Na + ions.…”