title: A novel tarantula toxin stabilizes the deactivated voltage sensor of bacterial sodium channel.
abstract: Voltage-gated sodium channels (NaVs) are activated by transiting the voltage sensor from the deactivated to the activated state. The crystal structures of several bacterial NaVs have captured the voltage sensor module (VSM) in an activated state, but structure of the deactivated voltage sensor remains elusive. In this study, we sought to identify peptide toxins stabilizing the deactivated VSM of bacterial NaVs. We screened fractions from several venoms and characterized a cystine knot toxin called JZTx-27 from the venom of tarantulaChilobrachys jingzhaoas a high-affinity antagonist of the prokaryotic NaVs NsVBa (nonselective voltage-gatedBacillus alcalophilus) and NaChBac (bacterial sodium channel fromBacillus halodurans) (IC50= 112 nM and 30 nM, respectively). JZTx-27 was more efficacious at weaker depolarizing voltages and significantly slowed the activation but accelerated the deactivation of NsVBa, whereas the local anesthetic drug lidocaine was shown to antagonize NsVBa without affecting channel gating. Mutation analysis confirmed that JZTx-27 bound to S3-4 linker of NsVBa, with F98 being the critical residue in determining toxin affinity. All electrophysiological data andin silicoanalysis suggested that JZTx-27 trapped VSM of NsVBa in one of the deactivated states. In mammalian NaVs, JZTx-27 preferably inhibited the inactivation of NaV1.5 by targeting the fourth transmembrane domain. To our knowledge, this is the first report of peptide antagonist for prokaryotic NaVs. More important, we proposed that JZTx-27 stabilized the NsVBa VSM in the deactivated state and may be used as a probe to determine the structure of the deactivated VSM of NaVs.-Tang, C., Zhou, X., Nguyen, P. T., Zhang, Y., Hu, Z., Zhang, C., Yarov-Yarovoy, V., DeCaen, P. G., Liang, S., Liu, Z. A novel tarantula toxin stabilizes the deactivated voltage sensor of bacterial sodium channel.
authors.affiliation: The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Tang
authors.affiliation: The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Physiology and Membrane Biology, University of California Davis, Davis, California, USA.
authors.forename: Phuong Tran
authors.initials: PT
authors.lastname: Nguyen
authors.affiliation: The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
authors.forename: Yunxiao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
authors.forename: Zhaotun
authors.initials: Z
authors.lastname: Hu
authors.affiliation: The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
authors.forename: Changxin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Physiology and Membrane Biology, University of California Davis, Davis, California, USA.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Yarov-Yarovoy
authors.affiliation: Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA liangsp@hunnu.edu.cn liuzh@hunnu.edu.cn.
authors.forename: Paul G
authors.initials: PG
authors.lastname: DeCaen
authors.affiliation: The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China; liangsp@hunnu.edu.cn.
authors.forename: Songping
authors.initials: S
authors.lastname: Liang
authors.affiliation: The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China; liuzh@hunnu.edu.cn.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001407:Bacillus / Q000378:metabolism*; D001665:Binding Sites; D055724:Electrophysiological Phenomena; D006801:Humans; D011485:Protein Binding; D011487:Protein Conformation; D013111:Spider Venoms / Q000737:chemistry*; D013112:Spiders / Q000502:physiology; D061567:Voltage-Gated Sodium Channel Blockers / Q000494:pharmacology*; D061566:Voltage-Gated Sodium Channels / Q000502:physiology*
chemical_list: D013111:Spider Venoms; D061567:Voltage-Gated Sodium Channel Blockers; D061566:Voltage-Gated Sodium Channels
keywords: NsVBa; deactivated state; peptide toxin