title: The crystal structure of a voltage-gated sodium channel.
abstract: Voltage-gated sodium (Na(V)) channels initiate electrical signalling in excitable cells and are the molecular targets for drugs and disease mutations, but the structural basis for their voltage-dependent activation, ion selectivity and drug block is unknown. Here we report the crystal structure of a voltage-gated Na(+) channel from Arcobacter butzleri (NavAb) captured in a closed-pore conformation with four activated voltage sensors at 2.7 Å resolution. The arginine gating charges make multiple hydrophilic interactions within the voltage sensor, including unanticipated hydrogen bonds to the protein backbone. Comparisons to previous open-pore potassium channel structures indicate that the voltage-sensor domains and the S4-S5 linkers dilate the central pore by pivoting together around a hinge at the base of the pore module. The NavAb selectivity filter is short, ∼4.6 Å wide, and water filled, with four acidic side chains surrounding the narrowest part of the ion conduction pathway. This unique structure presents a high-field-strength anionic coordination site, which confers Na(+) selectivity through partial dehydration via direct interaction with glutamate side chains. Fenestrations in the sides of the pore module are unexpectedly penetrated by fatty acyl chains that extend into the central cavity, and these portals are large enough for the entry of small, hydrophobic pore-blocking drugs. This structure provides the template for understanding electrical signalling in excitable cells and the actions of drugs used for pain, epilepsy and cardiac arrhythmia at the atomic level.
authors: Department of Pharmacology, University of Washington, Seattle, Washington 98195, USA.
authors: Jian
authors: J
authors: Payandeh
authors: Todd
authors: T
authors: Scheuer
authors: Ning
authors: N
authors: Zheng
authors: William A
authors: WA
authors: Catterall
mesh_terms: D000595:Amino Acid Sequence; D020640:Arcobacter / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D018360:Crystallography, X-Ray; D057927:Hydrophobic and Hydrophilic Interactions; D015640:Ion Channel Gating; D017136:Ion Transport; D008958:Models, Molecular; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D012964:Sodium / Q000378:metabolism; D026941:Sodium Channel Blockers / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D015222:Sodium Channels / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D015221:Potassium Channels; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D012964:Sodium; D011188:Potassium; D002118:Calcium