title: Expression and characterization of jingzhaotoxin-34, a novel neurotoxin from the venom of the tarantula Chilobrachys jingzhao.
abstract: Jingzhaotoxin-34 (JZTX-34) is a 35-residue polypeptide from the venom of Chinese tarantula Chilobrachys jingzhao. Our previous work reported its full-length cDNA sequence encoding a precursor with 87 residues. In this study we report the protein expression and biological function characterization. The toxin was efficiently expressed by the secretary pathway in yeast. Under whole-cell patch-clamp mode, the expressed JZTX-34 was able to inhibit tetrodotoxin-sensitive (TTX-S) sodium currents (IC(50) approximately 85 nM) while having no significant effects on tetrodotoxin-resistant (TTX-R) sodium currents on rat dorsal root ganglion neurons. The inhibition of TTX-S sodium channels was completely reversed by strong depolarization (+120 mV). Toxin treatment altered neither channel activation and inactivation kinetics nor recovery rate from inactivation. However, it is interesting to note that in contrast to huwentoxin-IV, a recently identified receptor site-4 toxin from Ornithoctonus huwena venom, 100 nM JZTX-34 caused a negative shift of steady-state inactivation curve of TTX-S sodium channels by approximately 10 mV. The results indicated that JZTX-34 might inhibit mammalian sensory neuronal sodium channels through a mechanism similar to HWTX-IV by trapping the IIS4 voltage sensor in the resting conformation, but their binding sites should not overlay completely.
authors.affiliation: The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, PR China.
authors.forename: Jinjun
authors.initials: J
authors.lastname: Chen
authors.forename: Yongqun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Mingqiang
authors.initials: M
authors.lastname: Rong
authors.forename: Liqun
authors.initials: L
authors.lastname: Zhao
authors.forename: Liping
authors.initials: L
authors.lastname: Jiang
authors.forename: Dongyi
authors.initials: D
authors.lastname: Zhang
authors.forename: Meichi
authors.initials: M
authors.lastname: Wang
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Xiao
authors.forename: Songping
authors.initials: S
authors.lastname: Liang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005727:Ganglia, Spinal / Q000166:cytology; D007700:Kinetics; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009498:Neurotoxins / Q000096:biosynthesis* / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016415:Sequence Alignment; D015222:Sodium Channels / Q000378:metabolism; D013111:Spider Venoms / Q000096:biosynthesis / Q000737:chemistry* / Q000494:pharmacology; D013112:Spiders / Q000737:chemistry*; D013779:Tetrodotoxin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D013997:Time Factors
chemical_list: D009498:Neurotoxins; D015222:Sodium Channels; D013111:Spider Venoms; C543185:jingzhaotoxin-34, Chilobrachys jingzhao; D013779:Tetrodotoxin