View source for 1lqi


==INSECTICIDAL ALPHA SCORPION TOXIN ISOLATED FROM THE VENOM OF SCORPION LEIURUS QUINQUESTRIATUS HEBRAEUS, NMR, 29 STRUCTURES==
<StructureSection load='1lqi' size='340' side='right'caption='[[1lqi]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1lqi]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Leiurus_hebraeus Leiurus hebraeus]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LQI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1LQI FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR, 29 models</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1lqi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1lqi OCA], [https://pdbe.org/1lqi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1lqi RCSB], [https://www.ebi.ac.uk/pdbsum/1lqi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1lqi ProSAT]</span></td></tr>
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== Function ==
[https://www.uniprot.org/uniprot/SCXA_LEIHE SCXA_LEIHE] Alpha toxins bind voltage-independently at site-3 of sodium channels (Nav) and inhibit the inactivation of the activated channels, thereby blocking neuronal transmission. The dissociation is voltage-dependent. This toxin is active on insects. It is also highly toxic to crustaceans and has a measurable but low toxicity to mice.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/lq/1lqi_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1lqi ConSurf].
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== Publication Abstract from PubMed ==
The solution structure of a recombinant active alpha-neurotoxin from Leiurus quinquestriatus hebraeus, Lqh(alpha)IT, was determined by proton two-dimensional nuclear magnetic resonance spectroscopy (2D NMR). This toxin is the most insecticidal among scorpion alpha-neurotoxins and, therefore, serves as a model for clarifying the structural basis for their biological activity and selective toxicity. A set of 29 structures was generated without constraint violations exceeding 0.4 A. These structures had root mean square deviations of 0.49 and 1.00 A with respect to the average structure for backbone atoms and all heavy atoms, respectively. Similarly to other scorpion toxins, the structure of Lqh(alpha)IT consists of an alpha-helix, a three-strand antiparallel beta-sheet, three type I tight turns, a five-residue turn, and a hydrophobic patch that includes tyrosine and tryptophan rings in a "herringbone" arrangement. Positive phi angles were found for Ala50 and Asn11, suggesting their proximity to functionally important regions of the molecule. The sample exhibited conformational heterogeneity over a wide range of experimental conditions, and two conformations were observed for the majority of protein residues. The ratio between these conformations was temperature-dependent, and the rate of their interconversions was estimated to be on the order of 1-5 s(-1) at 308 K. The conformation of the polypeptide backbone of Lqh(alpha)IT is very similar to that of the most active antimammalian scorpion alpha-toxin, AaHII, from Androctonus australis Hector (60% amino acid sequence homology). Yet, several important differences were observed at the 5-residue turn comprising residues Lys8-Cys12, the C-terminal segment, and the mutual disposition of these two regions. 2D NMR studies of the R64H mutant, which is 3 times more toxic than the unmodified Lqh(alpha)IT, demonstrated the importance of the spatial orientation of the last residue side chain for toxicity of Lqh(alpha)IT.

Solution structures of a highly insecticidal recombinant scorpion alpha-toxin and a mutant with increased activity.,Tugarinov V, Kustanovich I, Zilberberg N, Gurevitz M, Anglister J Biochemistry. 1997 Mar 4;36(9):2414-24. PMID:9054546<ref>PMID:9054546</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Hemolysin 3D structures|Hemolysin 3D structures]]
*[[Potassium channel toxin 3D structures|Potassium channel toxin 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Leiurus hebraeus]]
[[Category: Anglister J]]
[[Category: Gurevitz M]]
[[Category: Kustanovich I]]
[[Category: Tugarinov V]]
[[Category: Zilberberg N]]