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NMR Solution Structure of BmK-betaIT, an Excitatory Scorpion Toxin from Buthus martensi Karsch


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

NMR solution structure of BmK-betaIT, an excitatory scorpion beta-toxin without a 'hot spot' at the relevant position

Tong, X.Yao, J.He, F.Chen, X.Zheng, X.Xie, C.Wu, G.Zhang, N.Ding, J.Wu, H.

(2006) Biochem.Biophys.Res.Commun. 349: 890-899

  • DOI: 10.1016/j.bbrc.2006.08.131

  • PubMed Abstract: 
  • BmK-betaIT (previously named as Bm32-VI in the literature), an excitatory scorpion beta-toxin, is purified from the venom of the Chinese scorpion Buthus martensii Karsch. It features a primary sequence typical of the excitatory anti-insect toxins: tw ...

    BmK-betaIT (previously named as Bm32-VI in the literature), an excitatory scorpion beta-toxin, is purified from the venom of the Chinese scorpion Buthus martensii Karsch. It features a primary sequence typical of the excitatory anti-insect toxins: two contiguous Cys residues (Cys37-Cys38) and a shifted location of the fourth disulfide bridges (Cys38-Cys64), and demonstrates bioactivity characteristic of the excitatory beta-toxins. However, it is noteworthy that BmK-betaIT is not conserved with a glutamate residue at the preceding position of the third Cys residue, and is the first example having a non-glutamate residue at the relevant position in the excitatory scorpion beta-toxin subfamily. The 3D structure of BmK-betaIT is determined with 2D NMR spectroscopy and molecular modeling. The solution structure of BmK-betaIT is closely similar to those of BmK IT-AP and Bj-xtrIT, only distinct from the latter by lack of an alpha(0)-helix. The surface functional patch comparison with those of BmK IT-AP and Bj-xtrIT reveals their striking similarity in the spatial arrangement. These results infer that the functional surface of beta-toxins is composed of two binding regions and a functional site. The main binding site is consisted of hydrophobic residues surrounding the alpha(1)-helix and its preceding loop, which is common to all beta-type scorpion toxins affecting Na(+) channels. The second binding site, which determines the specificity of the toxin, locates at the C-terminus for excitatory insect beta-toxin, while rests at the beta-sheet and its linking loop for anti-mammal toxins. The functional site involved in the voltage sensor-trapping model, which characterizes the function of all beta-toxins, is the negatively charged residue Glu15.


    Organizational Affiliation

    State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Excitatory insect selective toxin 1
A
69Mesobuthus martensiiMutation(s): 0 
Find proteins for O61668 (Mesobuthus martensii)
Go to UniProtKB:  O61668
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 
  • Olderado: 1WWN Olderado

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-01-17
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance