1vtx | pdb_00001vtx
DELTA-ATRACOTOXIN-HV1 (VERSUTOXIN) FROM HADRONYCHE VERSUTA, NMR, 20 STRUCTURES
Structural highlights
Function[TXDT1_HADVE] Inhibits tetrodotoxin-sensitive voltage-gated sodium channels (Nav) by binding to site 3. Slows the inactivation, and causes a prolongation of action potential duration resulting in repetitive firing in autonomic and motor nerve fibers. Does not depolarize the resting potential. Does not affect tetrodotoxin-resistant sodium channels. This lethal neurotoxin is active on both insect and mammalian voltage-gated sodium channels. Pan-neuronal expression in Drosophila is lethal but flies engineered to express the toxin only in pacemaker neurons have profound defects in circadian rhythm but a normal lifespan.[1] [2] [3] [4] [5] [6] [7] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: Versutoxin (delta-ACTX-Hv1) is the major component of the venom of the Australian Blue Mountains funnel web spider, Hadronyche versuta. delta-ACTX-Hv1 produces potentially fatal neurotoxic symptoms in primates by slowing the inactivation of voltage-gated sodium channels; delta-ACTX-Hv1 is therefore a useful tool for studying sodium channel function. We have determined the three-dimensional structure of delta-ACTX-Hv1 as the first step towards understanding the molecular basis of its interaction with these channels. RESULTS: The solution structure of delta-ACTX-Hv1, determined using NMR spectroscopy, comprises a core beta region containing a triple-stranded antiparallel beta sheet, a thumb-like extension protruding from the beta region and a C-terminal 310 helix that is appended to the beta domain by virtue of a disulphide bond. The beta region contains a cystine knot motif similar to that seen in other neurotoxic polypeptides. The structure shows homology with mu-agatoxin-I, a spider toxin that also modifies the inactivation kinetics of vertebrate voltage-gated sodium channels. More surprisingly, delta-ACTX-Hv1 shows both sequence and structural homology with gurmarin, a plant polypeptide. This similarity leads us to suggest that the sweet-taste suppression elicited by gurmarin may result from an interaction with one of the downstream ion channels involved in sweet-taste transduction. CONCLUSIONS: delta-ACTX-Hv1 shows no structural homology with either sea anemone or alpha-scorpion toxins, both of which also modify the inactivation kinetics of voltage-gated sodium channels by interacting with channel recognition site 3. However, we have shown that delta-ACTX-Hv1 contains charged residues that are topologically related to those implicated in the binding of sea anemone and alpha-scorpion toxins to mammalian voltage-gated sodium channels, suggesting similarities in their mode of interaction with these channels. The structure of versutoxin (delta-atracotoxin-Hv1) provides insights into the binding of site 3 neurotoxins to the voltage-gated sodium channel.,Fletcher JI, Chapman BE, Mackay JP, Howden ME, King GF Structure. 1997 Nov 15;5(11):1525-35. PMID:9384567[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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