PDBsum entry 1ryv

Toxin

PDB id: 1ryv

Contents

Protein chain

36 a.a.

PDB id:

1ryv

Name:

Toxin

Title:

Three dimensional solution structure of the k27a mutant of sodium channels inhibitor hainantoxin-iv by 2d 1h-nmr

Structure:

Hainantoxin-iv. Chain: a. Synonym: hntx-iv. Engineered: yes. Mutation: yes

Source:

Synthetic: yes. Other_details: synthesized using standard fmoc chemistry.

NMR struc:

20 models

Authors:

D.Li,S.Lu,X.Gu,S.Liang

Key ref:

D.Li et al. (2004). Structure--activity relationships of hainantoxin-IV and structure determination of active and inactive sodium channel blockers. J Biol Chem, 279, 37734-37740. PubMed id: 15201273 DOI: 10.1074/jbc.M405765200

Date:

22-Dec-03 Release date: 13-Jan-04

Protein chain

D2Y232  (H4A01_CYRHA) -  Mu-theraphotoxin-Hhn1b 1 from Cyriopagopus hainanus

Seq: 86 a.a.

Struc: 36 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

DOI no: 10.1074/jbc.M405765200

J Biol Chem 279:37734-37740 (2004)

PubMed id: 15201273

Structure--activity relationships of hainantoxin-IV and structure determination of active and inactive sodium channel blockers.

D.Li, Y.Xiao, X.Xu, X.Xiong, S.Lu, Z.Liu, Q.Zhu, M.Wang, X.Gu, S.Liang.

ABSTRACT

Hainantoxin-IV (HNTX-IV) can specifically inhibit the neuronal tetrodotoxin-sensitive sodium channels and defines a new class of depressant spider toxin. The sequence of native HNTX-IV is ECLGFGKGCNPSNDQCCKSSNLVCSRKHRWCKYEI-NH(2). In the present study, to obtain further insight into the primary and tertiary structural requirements of neuronal sodium channel blockers, we determined the solution structure of HNTX-IV as a typical inhibitor cystine knot motif and synthesized four mutants designed based on the predicted sites followed by structural elucidation of two inactive mutants. Pharmacological studies indicated that the S12A and R26A mutants had activities near that of native HNTX-IV, while K27A and R29A demonstrated activities reduced by 2 orders of magnitude. (1)H MR analysis showed the similar molecular conformations for native HNTX-IV and four synthetic mutants. Furthermore, in the determined structures of K27A and R29A, the side chains of residues 27 and 29 were located in the identical spatial position to those of native HNTX-IV. These results suggested that residues Ser(12), Arg(26), Lys(27), and Arg(29) were not responsible for stabilizing the distinct conformation of HNTX-IV, but Lys(27) and Arg(29) were critical for the bioactivities. The potency reductions produced by Ala substitutions were primarily due to the direct interaction of the essential residues Lys(27) and Arg(29) with sodium channels rather than to a conformational change. After comparison of these structures and activities with correlated toxins, we hypothesized that residues Lys(27), Arg(29), His(28), Lys(32), Phe(5), and Trp(30) clustered on one face of HNTX-IV were responsible for ligand binding.

Selected figure(s)

Figure 2.
FIG. 2. Structural comparison of HNTX-IV and correlated toxin molecules. A, ensembles of 20 energy-refined conformers representing the solution structures of native HNTX-IV, K27A, and R29A. The backbones are shown in cyan, green, and gray, respectively. Positively charged side chains are shown in blue, and negatively charged side chains are shown in red. B, comparison of HNTX-IV to conotoxin GS (CTX-GS) and µ-conotoxin GIIIA (CTX-GIIIA) (conotoxin GS, Protein Data Bank code 1AG7 [PDB] ; µ-conotoxin GIIIA, Protein Data Bank code 1TCG [PDB] ). The -sheet is shown in yellow, the turn is shown in blue, and the random coil structure is shown in green. Three disulfide bonds of each molecule are indicated. The letters N and C refer to the amino and carboxyl termini, respectively.

Figure 7.
FIG. 7. Solution structure characterization of HNTX-IV. A, surface profile of HNTX-IV. a, surface profile of predicted active sites. b, surface profile of putative active sites. Blue, mauve, and cyan regions represent positively charged, polar, and hydrophobic residues, respectively. B, backbone superposition of native HNTX-IV (blue), K27A (green), and R29A (red). 27 and 29 indicate the positions of substituted amino acid residues. The fit was done using the common secondary structure elements. The letters N and C refer to the amino and carboxyl termini, respectively.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 37734-37740) copyright 2004.

Figures were selected by an automated process.