View source for 1tii


==ESCHERICHIA COLI HEAT LABILE ENTEROTOXIN TYPE IIB==
<StructureSection load='1tii' size='340' side='right'caption='[[1tii]], [[Resolution|resolution]] 2.25&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1tii]] is a 7 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TII OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1TII 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]] 2.25&#8491;</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=1tii FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1tii OCA], [https://pdbe.org/1tii PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1tii RCSB], [https://www.ebi.ac.uk/pdbsum/1tii PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1tii ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/E2BB_ECOLX E2BB_ECOLX] The biological activity of the toxin is produced by the A chain, which activates intracellular adenyl cyclase.
== 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/ti/1tii_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=1tii ConSurf].
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== Publication Abstract from PubMed ==
BACKGROUND: Cholera toxin from Vibrio cholerae and the type I heat-labile enterotoxins (LT-Is) from Escherichia coli are oligomeric proteins with AB5 structures. The type II heat-labile enterotoxins (LT-IIs) from E. coli are structurally similar to, but antigenically distinct from, the type I enterotoxins. The A subunits of type I and type II enterotoxins are homologous and activate adenylate cyclase by ADP-ribosylation of a G protein subunit, G8 alpha. However, the B subunits of type I and type II enterotoxins differ dramatically in amino acid sequence and ganglioside-binding specificity. The structure of LT-IIb was determined both as a prototype for other LT-IIs and to provide additional insights into structure/function relationships among members of the heat-labile enterotoxin family and the superfamily of ADP-ribosylating protein toxins. RESULTS: The 2.25 A crystal structure of the LT-IIb holotoxin has been determined. The structure reveals striking similarities with LT-I in both the catalytic A subunit and the ganglioside-binding B subunits. The latter form a pentamer which has a central pore with a diameter of 10-18 A. Despite their similarities, the relative orientation between the A polypeptide and the B pentamer differs by 24 degrees in LT-I and LT-IIb. A common hydrophobic ring was observed at the A-B5 interface which may be important in the cholera toxin family for assembly of the AB5 heterohexamer. A cluster of arginine residues at the surface of the A subunit of LT-I and cholera toxin, possibly involved in assembly, is also present in LT-IIb. The ganglioside receptor binding sites are localized, as suggested by mutagenesis, and are in a position roughly similar to the sites where LT-I binds its receptor. CONCLUSIONS: The structure of LT-IIb provides insight into the sequence diversity and structural similarity of the AB5 toxin family. New knowledge has been gained regarding the assembly of AB5 toxins and their active-site architecture.

Crystal structure of a new heat-labile enterotoxin, LT-IIb.,van den Akker F, Sarfaty S, Twiddy EM, Connell TD, Holmes RK, Hol WG Structure. 1996 Jun 15;4(6):665-78. PMID:8805549<ref>PMID:8805549</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Hol WGJ]]
[[Category: Van Den Akker F]]