1T0Z

Structure of an Excitatory Insect-specific Toxin with an Analgesic Effect on Mammalian from Scorpion Buthus martensii Karsch


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.200 

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This is version 1.2 of the entry. See complete history


Literature

Structure of an excitatory insect-specific toxin with an analgesic effect on mammals from the scorpion Buthus martensii Karsch.

Li, C.Guan, R.J.Xiang, Y.Zhang, Y.Wang, D.C.

(2005) Acta Crystallogr D Biol Crystallogr 61: 14-21

  • DOI: 10.1107/S0907444904025703
  • Primary Citation of Related Structures:  
    1T0Z

  • PubMed Abstract: 
  • BmK IT-AP is an excitatory insect-specific beta-toxin with analgesic effect from the Chinese scorpion Buthus martensii Karsch (BmK) and consists of 72 residues cross-linked by four disulfide bridges. The crystal structure of BmK IT-AP has been determined at a resolution of 2 ...

    BmK IT-AP is an excitatory insect-specific beta-toxin with analgesic effect from the Chinese scorpion Buthus martensii Karsch (BmK) and consists of 72 residues cross-linked by four disulfide bridges. The crystal structure of BmK IT-AP has been determined at a resolution of 2.6 A by molecular replacement. Compared with the mammal-selective alpha-toxins consisting of 64 residues from the scorpion BmK, the general fold of IT-AP features an additional one-and-a-half turn alpha-helix at the C-terminal residues 59-65 with a shifted disulfide bridge Cys38-Cys64. The extension and 'wiggling' of the C-terminal segment led to a reshaping of the bioactive surface, including the complete destruction of the active site RC comprising the reverse turn (8-12) and C-terminal residues 58-64, the disappearance of an active surface formed by two aromatic residues Trp38 and Tyr42 and the covering of the conserved aromatic cluster Tyr5, Tyr35 and Trp47, which are all critical for the structure and function of mammal-selective alpha-toxins. Bj-xtrIT, the only other excitatory insect-specific toxin whose three-dimensional structure has been determined, is distinct from BmK IT-AP. A functionally important five-residue alpha-helix (alpha0) formed by residues 17-21 in Bj-xtrIT is deleted in BmK IT-AP and helix alpha1 is immediately connected to Cys16 through two residues Leu17 and Phe18. Accordingly, the functional surface of this region in Bj-xtrIT has also been reshaped in IT-AP, which implies subtle differences between BmK IT-AP and Bj-xtrIT in binding to the receptor, although most other critical residues for structure and function adopt almost identical conformations. The crystal structure of IT-AP also forms a sound basis for further study of the structure-function determinants of the analgesic effect.


    Related Citations: 
    • Molecular characterization of a new excitatory insect neurotoxin with an analgesic effect on mice from the scorpion Buthus martensii Karsch
      Xiong, Y.-M., Lan, Z.-D., Wang, M., Liu, B., Liu, X.-Q., Fei, H., Xu, L.-G., Xia, Q.-C., Wang, C.-G., Wang, D.-C., Chi, Z.-W.
      (1999) Toxicon 37: 1165
    • Crystallization and preliminary X-ray analyses of insect neurotoxins with analgesic effect from the scorpion Buthus martensii Karsch
      Guan, R.-J., Liu, X.-Q., Liu, B., Wang, M., Wang, D.-C.
      (2000) Acta Crystallogr D Biol Crystallogr 56: 1012

    Organizational Affiliation

    Center for Structural and Molecular Biology, Institute of Biophysics, Chinese Academy of Science, Beijing 100101, People's Republic of China.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
insect neurotoxinA, B72Mesobuthus martensiiMutation(s): 0 
Gene Names: IT-AP
Membrane Entity: Yes 
UniProt
Find proteins for O77091 (Mesobuthus martensii)
Explore O77091 
Go to UniProtKB:  O77091
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.200 
  • Space Group: P 64 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 64.971α = 90
b = 64.971β = 90
c = 173.482γ = 120
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
SCALEPACKdata scaling
MOLREPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-12-28
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance