1ciy

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[[Image:1ciy.gif|left|200px]]<br /><applet load="1ciy" size="350" color="white" frame="true" align="right" spinBox="true"
 
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caption="1ciy, resolution 2.25&Aring;" />
 
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'''INSECTICIDAL TOXIN: STRUCTURE AND CHANNEL FORMATION'''<br />
 
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==Overview==
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==INSECTICIDAL TOXIN: STRUCTURE AND CHANNEL FORMATION==
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The activated 65 kDa lepidopteran-specific CryIA(a) toxin from the commercially most important strain Bacillus thuringiensis var. kurstaki HD-1 has been investigated by X-ray diffraction and for its ability to form channels in planar lipid bilayers. Its three-dimensional structure has been determined by a multiple isomorphous replacement method and refined at 2.25 A resolution to an R-factor of 0.168 for data with I &gt; 2 delta (I). The toxin is made of three distinct domains. The N-terminal domain is a bundle of eight alpha-helices with the central, relatively hydrophobic helix surrounded by amphipathic helices. The middle and C-terminal domains contain mostly beta-sheets. Comparison with the structure of CryIIIA, a coleopteran-specific toxin, shows that although the fold of these two proteins is similar, there are significant structural differences within domain II. This finding supports the conclusions from genetic studies that domain II is involved in recognition and binding to cell surface receptors. The distribution of electrostatic potential on the surface of the molecule is non-uniform and identifies one side of the alpha-helical domain as negatively charged. The predominance of arginine residues as basic residues ensures that the observed positive charge distribution is also maintained in the highly alkaline environment found in the lepidopteran midgut. Structurally important salt bridges that are conserved across Cry sequences were identified and their possible role in toxin action was postulated. In planar lipid bilayers, CryIA(a) forms cation-selective channels, whose conductance is significantly smaller than that reported for CryIIIA but similar to those of other Cry toxins.
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<StructureSection load='1ciy' size='340' side='right'caption='[[1ciy]], [[Resolution|resolution]] 2.25&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1ciy]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Bacillus_thuringiensis Bacillus thuringiensis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CIY OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1CIY FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.25&#8491;</td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1ciy FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ciy OCA], [https://pdbe.org/1ciy PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1ciy RCSB], [https://www.ebi.ac.uk/pdbsum/1ciy PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1ciy ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/CR1AA_BACTK CR1AA_BACTK] Promotes colloidosmotic lysis by binding to the midgut epithelial cells of many lepidopteran larvae.
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ci/1ciy_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</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=1ciy ConSurf].
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<div style="clear:both"></div>
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==About this Structure==
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==See Also==
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1CIY is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_thuringiensis Bacillus thuringiensis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CIY OCA].
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*[[Delta-endotoxin|Delta-endotoxin]]
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*[[Pesticidal crystal protein|Pesticidal crystal protein]]
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==Reference==
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__TOC__
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Bacillus thuringiensis CryIA(a) insecticidal toxin: crystal structure and channel formation., Grochulski P, Masson L, Borisova S, Pusztai-Carey M, Schwartz JL, Brousseau R, Cygler M, J Mol Biol. 1995 Dec 1;254(3):447-64. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7490762 7490762]
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</StructureSection>
[[Category: Bacillus thuringiensis]]
[[Category: Bacillus thuringiensis]]
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[[Category: Single protein]]
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[[Category: Large Structures]]
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[[Category: Cygler, M.]]
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[[Category: Cygler M]]
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[[Category: Grochulski, P.]]
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[[Category: Grochulski P]]
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[[Category: delta-endotoxin cryia(a)]]
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[[Category: icp]]
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[[Category: toxin]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:06:32 2008''
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Current revision

INSECTICIDAL TOXIN: STRUCTURE AND CHANNEL FORMATION

PDB ID 1ciy

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