Sequence-specific Assignment of ¹H-NMR Resonance and Determination of the Secondary Structure of Jingzhaotoxin-I

Abstract Jingzhaotoxin-I (JZTX-I) purified from the venom of the spider Chilobrachys jingzhao is a novel neurotoxin preferentially inhibiting cardiac sodium channel inactivation by binding to receptor site 3. The structure of this toxin in aqueous solution was investigated using 2-D ¹H-NMR techniques. The complete sequence-specific assignments of proton resonance in the ¹H-NMR spectra of JZTX-I were obtained by analyzing a series of 2-D spectra, including DQF-COSY, TOCSY and NOESY spectra, in H₂O and D₂O. All the backbone protons except for Gln4 and more than 95% of the side-chain protons were identified by d_αN, d_αγ, d_βN, and d_NN connectivities in the NOESY spectrum. These studies provide a basis for the further determination of the solution conformation of JZTX-I. Furthermore, the secondary structure of JZTX-I was identified from NMR data. It consists mainly of a short triple-stranded antiparallel β-sheet with Trp7-Cys9, Phe20-Lys23 and Leu28-Trp31. The characteristics of the secondary structure of JZTX-I are similar to those of huwentoxin-I (HWTX-I) and hainantoxin-IV (HNTX-IV), whose structures in solution have previously been reported.

Edited by Hong-Yu HU