View source for 1seg


==Crystal structure of a toxin chimera between Lqh-alpha-IT from the scorpion Leiurus quinquestriatus hebraeus and AAH2 from Androctonus australis hector==
<StructureSection load='1seg' size='340' side='right'caption='[[1seg]], [[Resolution|resolution]] 1.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1seg]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Androctonus_australis_hector Androctonus australis hector]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SEG OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1SEG FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NO3:NITRATE+ION'>NO3</scene>, <scene name='pdbligand=PPI:PROPANOIC+ACID'>PPI</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></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=1seg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1seg OCA], [https://pdbe.org/1seg PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1seg RCSB], [https://www.ebi.ac.uk/pdbsum/1seg PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1seg ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SCX2_ANDAU SCX2_ANDAU] Alpha toxins bind voltage-independently at site-3 of sodium channels (Nav) and inhibit the inactivation of the activated channels, thereby blocking neuronal transmission. This toxin is active against mammals.
== 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/se/1seg_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.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=1seg ConSurf].
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== Publication Abstract from PubMed ==
Scorpion alpha-toxins are similar in their mode of action and three-dimensional structure but differ considerably in affinity for various voltage-gated sodium channels (NaChs). To clarify the molecular basis of the high potency of the alpha-toxin LqhalphaIT (from Leiurus quinquestriatus hebraeus) for insect NaChs, we identified by mutagenesis the key residues important for activity. We have found that the functional surface is composed of two distinct domains: a conserved "Core-domain" formed by residues of the loops connecting the secondary structure elements of the molecule core and a variable "NC-domain" formed by a five-residue turn (residues 8-12) and a C-terminal segment (residues 56-64). We further analyzed the role of these domains in toxin activity on insects by their stepwise construction onto the scaffold of the anti-mammalian alpha-toxin, Aah2 (from Androctonus australis hector). The chimera harboring both domains, Aah2(LqhalphaIT(face)), was as active to insects as LqhalphaIT. Structure determination of Aah2(LqhalphaIT(face)) by x-ray crystallography revealed that the NC-domain deviates from that of Aah2 and forms an extended protrusion off the molecule core as appears in LqhalphaIT. Notably, such a protrusion is observed in all alpha-toxins active on insects. Altogether, the division of the functional surface into two domains and the unique configuration of the NC-domain illuminate the molecular basis of alpha-toxin specificity for insects and suggest a putative binding mechanism to insect NaChs.

Molecular basis of the high insecticidal potency of scorpion alpha-toxins.,Karbat I, Frolow F, Froy O, Gilles N, Cohen L, Turkov M, Gordon D, Gurevitz M J Biol Chem. 2004 Jul 23;279(30):31679-86. Epub 2004 May 8. PMID:15133045<ref>PMID:15133045</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1seg" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Androctonus australis hector]]
[[Category: Large Structures]]
[[Category: Cohen L]]
[[Category: Frolow F]]
[[Category: Froy O]]
[[Category: Gilles N]]
[[Category: Gordon D]]
[[Category: Gurevitz M]]
[[Category: Karbat I]]
[[Category: Turkov M]]