1c55
NMR SOLUTION STRUCTURE OF BUTANTOXIN
Structural highlights
FunctionKA121_TITSE Potently blocks Kv1.3/KCNA3, Kv1.2/KCNA2, and Shaker potassium channels (PubMed:24590385) and inhibits high conductance calcium-activated potassium channels (PubMed:10082164). The IC(50) of Kv1.3/KCNN3 and Kv1.2/KCNN2 are 0.55 nM and 6.19 nM respectively (PubMed:24590385). In addition, it stimulates the release of NO, IL-6 and TNF-alpha in J774.1 cells (PubMed:21549737) and presents a pro-inflammatory activity in mice (PubMed:23085190).[1] [2] [3] [4] Publication Abstract from PubMedThe NMR structure of a new toxin, butantoxin (BuTX), which is present in the venoms of the three Brazilian scorpions Tityus serrulatus, Tityus bahiensis, and Tityus stigmurus, has been investigated. This toxin was shown to reversibly block the Shaker B potassium channels (K(d) approximately 660 nM) and inhibit the proliferation of T-cells and the interleukin-2 production of antigen-stimulated T-helper cells. BuTX is a 40 amino acid basic protein stabilized by the four disulfide bridges: Cys2-Cys5, Cys10-Cys31, Cys16-Cys36, and Cys20-Cys38. The latter three are conserved among all members of the short-chain scorpion toxin family, while the first is unique to BuTX. The three-dimensional structure of BuTX was determined using (1)H-NMR spectroscopy. NOESY, phase sensitive COSY (PH-COSY), and amide hydrogen exchange data were used to generate constraints for molecular modeling calculations. Distance geometry and simulated annealing calculations were performed to generate a family of 49 structures free of constraint violations. The secondary structure of BuTX consists of a short 2(1/2) turn alpha-helix (Glu15-Phe23) and a beta-sheet. The beta-sheet is composed of two well-defined antiparallel strands (Gly29-Met32 and Lys35-Cys38) connected by a type-I' beta-turn (Asn33-Asn34). Residues Cys5-Ala9 form a quasi-third strand of the beta-sheet. The N-terminal C2-C5 disulfide bridge unique to this toxin does not appear to confer stability to the protein. NMR solution structure of butantoxin.,Holaday SK Jr, Martin BM, Fletcher PL Jr, Krishna NR Arch Biochem Biophys. 2000 Jul 1;379(1):18-27. PMID:10864437[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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