1t0z

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spinqualitylabelsall models 1t0z, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

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

Overview

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.

About this Structure

1T0Z is a Single protein structure of sequence from Mesobuthus martensii with SO4 as ligand. Full crystallographic information is available from OCA.

Reference

Structure of an excitatory insect-specific toxin with an analgesic effect on mammals from the scorpion Buthus martensii Karsch., Li C, Guan RJ, Xiang Y, Zhang Y, Wang DC, Acta Crystallogr D Biol Crystallogr. 2005 Jan;61(Pt 1):14-21. Epub 2004, Dec 17. PMID:15608371

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