1bcg: Difference between revisions
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[[Image: | ==SCORPION TOXIN BJXTR-IT== | ||
<StructureSection load='1bcg' size='340' side='right' caption='[[1bcg]], [[Resolution|resolution]] 2.10Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[1bcg]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Hottentotta_judaicus Hottentotta judaicus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BCG OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1BCG FirstGlance]. <br> | |||
</td></tr><tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1bcg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1bcg OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1bcg RCSB], [http://www.ebi.ac.uk/pdbsum/1bcg PDBsum]</span></td></tr> | |||
<table> | |||
== 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/bc/1bcg_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/chain_selection.php?pdb_ID=2ata ConSurf]. | |||
<div style="clear:both"></div> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
BACKGROUND: Scorpion neurotoxins, which bind and modulate sodium channels, have been divided into two groups, the alpha and beta toxins, according to their activities. The beta-toxin class includes the groups of excitatory and depressant toxins, which differ in their mode of action and are highly specific against insects. The three-dimensional structures of several alpha and beta toxins have been determined at high resolution, but no detailed 3D structure of an excitatory toxin has been presented so far. RESULTS: The crystal structure of an anti-insect excitatory toxin from the scorpion Buthotus judaicus, Bj-xtrIT, has been determined at 2.1 A resolution and refined to an R factor of 0.209. The first 59 residues form a closely packed module, structurally similar to the conserved alpha and beta toxins ('long toxins') affecting sodium channels. The last 17 residues form a C-terminal extension not previously seen in scorpion toxins. It comprises a short alpha helix anchored to the N-terminal module by a disulfide bridge and is followed by a highly mobile stretch of seven residues, of which only four are seen in the electron-density map. This mobile peptide covers part of a conserved hydrophobic surface that is thought to be essential for interaction with the channel in several long toxins. CONCLUSIONS: Replacement of the last seven residues by a single glycine abolishes the activity of Bj-xtrIT, strongly suggesting that these residues are intimately involved in the interaction with the channel. Taken together with the partial shielding of the conserved hydrophobic surface and the proximity of the C terminus to an adjacent surface rich in charged residues, it seems likely that the bioactive surface of Bj-xtrIT is formed by residues surrounding the C terminus. The 3D structure and a recently developed expression system for Bj-xtrIT pave the way for identifying the structural determinants involved in the bioactivity and anti-insect specificity of excitatory toxins. | |||
An excitatory scorpion toxin with a distinctive feature: an additional alpha helix at the C terminus and its implications for interaction with insect sodium channels.,Oren DA, Froy O, Amit E, Kleinberger-Doron N, Gurevitz M, Shaanan B Structure. 1998 Sep 15;6(9):1095-103. PMID:9753689<ref>PMID:9753689</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
== | |||
< | |||
[[Category: Hottentotta judaicus]] | [[Category: Hottentotta judaicus]] | ||
[[Category: Amit, E.]] | [[Category: Amit, E.]] | ||
Revision as of 06:07, 7 August 2014
SCORPION TOXIN BJXTR-ITSCORPION TOXIN BJXTR-IT
Structural highlights
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: Scorpion neurotoxins, which bind and modulate sodium channels, have been divided into two groups, the alpha and beta toxins, according to their activities. The beta-toxin class includes the groups of excitatory and depressant toxins, which differ in their mode of action and are highly specific against insects. The three-dimensional structures of several alpha and beta toxins have been determined at high resolution, but no detailed 3D structure of an excitatory toxin has been presented so far. RESULTS: The crystal structure of an anti-insect excitatory toxin from the scorpion Buthotus judaicus, Bj-xtrIT, has been determined at 2.1 A resolution and refined to an R factor of 0.209. The first 59 residues form a closely packed module, structurally similar to the conserved alpha and beta toxins ('long toxins') affecting sodium channels. The last 17 residues form a C-terminal extension not previously seen in scorpion toxins. It comprises a short alpha helix anchored to the N-terminal module by a disulfide bridge and is followed by a highly mobile stretch of seven residues, of which only four are seen in the electron-density map. This mobile peptide covers part of a conserved hydrophobic surface that is thought to be essential for interaction with the channel in several long toxins. CONCLUSIONS: Replacement of the last seven residues by a single glycine abolishes the activity of Bj-xtrIT, strongly suggesting that these residues are intimately involved in the interaction with the channel. Taken together with the partial shielding of the conserved hydrophobic surface and the proximity of the C terminus to an adjacent surface rich in charged residues, it seems likely that the bioactive surface of Bj-xtrIT is formed by residues surrounding the C terminus. The 3D structure and a recently developed expression system for Bj-xtrIT pave the way for identifying the structural determinants involved in the bioactivity and anti-insect specificity of excitatory toxins. An excitatory scorpion toxin with a distinctive feature: an additional alpha helix at the C terminus and its implications for interaction with insect sodium channels.,Oren DA, Froy O, Amit E, Kleinberger-Doron N, Gurevitz M, Shaanan B Structure. 1998 Sep 15;6(9):1095-103. PMID:9753689[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References |
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