title: Molecular determinant for the tarantula toxin Jingzhaotoxin-I slowing the fast inactivation of voltage-gated sodium channels.
abstract: Peptide toxins often have divergent pharmacological functions and are powerful tools for a deep review on the current understanding of the structure-function relationships of voltage-gated sodium channels (VGSCs). However, knowing about the interaction of site 3 toxins from tarantula venoms with VGSCs is not sufficient. In the present study, using whole-cell patch clamp technique, we determined the effects of Jingzhaotoxin-I (JZTX-I) on five VGSC subtypes expressed in HEK293 cells. The results showed that JZTX-I could inhibit the inactivation of rNav1.2, rNav1.3, rNav1.4, hNav1.5 and hNav1.7 channels with the IC50 of 870 ± 8 nM, 845 ± 4 nM, 339 ± 5 nM, 335 ± 9 nM, and 348 ± 6 nM, respectively. The affinity of the toxin interaction with subtypes (rNav1.4, hNav1.5, and hNav1.7) was only 2-fold higher than that for subtypes (rNav1.2 and rNav1.3). The toxin delayed the inactivation of VGSCs without affecting the activation and steady-state inactivation kinetics in the physiological range of voltages. Site-directed mutagenesis indicated that the toxin interacted with site 3 located at the extracellular S3-S4 linker of domain IV, and the acidic residue Asp at the position1609 in hNav1.5 was crucial for JZTX-I activity. Our results provide new insights in single key residue that allows toxins to recognize distinct ion channels with similar potency and enhance our understanding of the structure-function relationships of toxin-channel interactions.
authors.affiliation: Department of Biochemistry and Molecular Biology, Hunan University of Chinese Medicine, Changsha 410208, Hunan, China; Division of Stem Cell Regulation and Application, Hunan University of Chinese Medicine, Changsha 410208, Hunan, China. Electronic address: taohuai123@126.com.
authors.forename: Huai
authors.initials: H
authors.lastname: Tao
authors.affiliation: Department of Orthopedics, The Second Xiangya Hospital of Central South University, Changsha 410011, Hunan, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Chen
authors.affiliation: Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, Hunan, China.
authors.forename: Min
authors.initials: M
authors.lastname: Lu
authors.affiliation: Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, Hunan, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha 410013, Hunan, China.
authors.forename: Meichun
authors.initials: M
authors.lastname: Deng
authors.affiliation: Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, Hunan, China.
authors.forename: Xiongzhi
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, Hunan, China.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, Hunan, China. Electronic address: liangsp@hunnu.edu.cn.
authors.forename: Songping
authors.initials: S
authors.lastname: Liang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057809:HEK293 Cells; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D013111:Spider Venoms / Q000737:chemistry / Q000494:pharmacology*; D013112:Spiders / Q000502:physiology*; D061567:Voltage-Gated Sodium Channel Blockers / Q000737:chemistry / Q000494:pharmacology*; D061566:Voltage-Gated Sodium Channels / Q000378:metabolism*
chemical_list: D010455:Peptides; D013111:Spider Venoms; D061567:Voltage-Gated Sodium Channel Blockers; D061566:Voltage-Gated Sodium Channels; C500354:jingzhaotoxin-I, Chilobrachys jingzhao
keywords: Inactivation; Jingzhaotoxin-I; Mutation; Voltage-gated sodium channels