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== | ==ANALYSIS OF SIDE-CHAIN ORGANIZATION ON A REFINED MODEL OF CHARYBDOTOXIN: STRUCTURAL AND FUNCTIONAL IMPLICATIONS== | ||
<StructureSection load='2crd' size='340' side='right'caption='[[2crd]]' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[2crd]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Leiurus_hebraeus Leiurus hebraeus]. The February 2003 RCSB PDB [https://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month] feature on ''Potassium Channels'' by Shuchismita Dutta and David S. Goodsell is [https://dx.doi.org/10.2210/rcsb_pdb/mom_2003_2 10.2210/rcsb_pdb/mom_2003_2]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2CRD OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2CRD FirstGlance]. <br> | |||
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR, 12 models</td></tr> | |||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=PCA:PYROGLUTAMIC+ACID'>PCA</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=2crd FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2crd OCA], [https://pdbe.org/2crd PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2crd RCSB], [https://www.ebi.ac.uk/pdbsum/2crd PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2crd ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/KAX11_LEIHE KAX11_LEIHE] This toxin inhibits numerous potassium channels: shaker (Ki=227 nM), Kv1.2/KCNA2 (nanomolar range), Kv1.3/KCNA3 (nanomolar range), Kv1.5/KCNA5 (Kd>100 nM), Kv1.6/KCNA6 (Ki=22 nM), KCa1.1/KCNMA1 (IC(50)=5.9 nM). It blocks channel activity by a simple bimolecular inhibition process. It also shows a weak interaction with nicotinic acetylcholine receptors (nAChR), suggesting it may weakly inhibit it (PubMed:31276191). It also exhibits pH-specific antimicrobial activities against bacteria (B.subtilis, E.coli and S.aureus) and the fungus C.albicans (PubMed:15118082).<ref>PMID:12527813</ref> <ref>PMID:15118082</ref> <ref>PMID:20007782</ref> <ref>PMID:2477548</ref> <ref>PMID:31276191</ref> <ref>PMID:7517498</ref> <ref>PMID:8204618</ref> | |||
== 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/cr/2crd_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=2crd ConSurf]. | |||
<div style="clear:both"></div> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
The spatial organization of side chains on a refined model of charybdotoxin is presented. First, the structural role of two groups of well-defined, low-accessible side chains (Thr3, Val5, Val16, Leu20, Cys33 and Leu20, His21, Thr23, Cys17, Cys35) is discussed. These side chains are conserved in three out of the five known scorpion toxins acting on K+ channels. Interestingly, they are not conserved in scyllatoxin which presents a slightly different secondary structure organization. Second, the spatial organization of all positively charged residues is analyzed. Comparison with the results presented by Park and Miller [(1992) Biochemistry (preceding paper in this issue)] shows that all functionally important positive residues are located on the beta-sheet side of the toxin. These results are different from those obtained by Auguste et al. [(1992) Biochemistry 31, 648-654] on scyllatoxin, which blocks a different type of K+ channel. This study shows, in fact, that functionally important positive residues are located on the helix side of the toxin. Thus, charybdotoxin and scyllatoxin, which present the same global fold, interact with two different classes of K+ channels by two different parts of the motif. | The spatial organization of side chains on a refined model of charybdotoxin is presented. First, the structural role of two groups of well-defined, low-accessible side chains (Thr3, Val5, Val16, Leu20, Cys33 and Leu20, His21, Thr23, Cys17, Cys35) is discussed. These side chains are conserved in three out of the five known scorpion toxins acting on K+ channels. Interestingly, they are not conserved in scyllatoxin which presents a slightly different secondary structure organization. Second, the spatial organization of all positively charged residues is analyzed. Comparison with the results presented by Park and Miller [(1992) Biochemistry (preceding paper in this issue)] shows that all functionally important positive residues are located on the beta-sheet side of the toxin. These results are different from those obtained by Auguste et al. [(1992) Biochemistry 31, 648-654] on scyllatoxin, which blocks a different type of K+ channel. This study shows, in fact, that functionally important positive residues are located on the helix side of the toxin. Thus, charybdotoxin and scyllatoxin, which present the same global fold, interact with two different classes of K+ channels by two different parts of the motif. | ||
Analysis of side-chain organization on a refined model of charybdotoxin: structural and functional implications.,Bontems F, Gilquin B, Roumestand C, Menez A, Toma F Biochemistry. 1992 Sep 1;31(34):7756-64. PMID:1380828<ref>PMID:1380828</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
[[Category: Leiurus | <div class="pdbe-citations 2crd" style="background-color:#fffaf0;"></div> | ||
==See Also== | |||
*[[Potassium channel toxin 3D structures|Potassium channel toxin 3D structures]] | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Large Structures]] | |||
[[Category: Leiurus hebraeus]] | |||
[[Category: Potassium Channels]] | [[Category: Potassium Channels]] | ||
[[Category: | [[Category: RCSB PDB Molecule of the Month]] | ||
[[Category: Bontems | [[Category: Bontems F]] | ||
[[Category: Gilquin | [[Category: Gilquin B]] | ||
[[Category: Menez | [[Category: Menez A]] | ||
[[Category: Roumestand | [[Category: Roumestand C]] | ||
[[Category: Toma | [[Category: Toma F]] | ||