1wwn
From Proteopedia
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NMR Solution Structure of BmK-betaIT, an Excitatory Scorpion Toxin from Buthus martensi Karsch
Overview
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.
About this Structure
1WWN is a Single protein structure of sequence from Mesobuthus martensii. Full crystallographic information is available from OCA.
Reference
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, Biochem Biophys Res Commun. 2006 Oct 27;349(3):890-9. Epub 2006 Aug 30. PMID:16970911
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