1ltg

<table><tr><td colspan='2'>[[1ltg]] is a 7 chain structure with sequence from [http://en.wikipedia.org/wiki/"bacillus_coli"_migula_1895 "bacillus coli" migula 1895]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LTG OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1LTG FirstGlance]. <br>

</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ltg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ltg OCA], [http://pdbe.org/1ltg PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1ltg RCSB], [http://www.ebi.ac.uk/pdbsum/1ltg PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1ltg ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/ELBP_ECOLX ELBP_ECOLX]] The biological activity of the toxin is produced by the A chain, which activates intracellular adenyl cyclase. [[http://www.uniprot.org/uniprot/ELAP_ECOLX ELAP_ECOLX]] The biological activity of the toxin is produced by the A chain, which activates intracellular adenyl cyclase.

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== Publication Abstract from PubMed ==

The heat-labile enterotoxin from Escherichia coli (LT) is a member of the cholera toxin family. These and other members of the larger class of AB5 bacterial toxins act through catalyzing the ADP-ribosylation of various intracellular targets including Gs alpha. The A subunit is responsible for this covalent modification, while the B pentamer is involved in receptor recognition. We report here the crystal structure of an inactive single-site mutant of LT in which arginine 7 of the A subunit has been replaced by a lysine residue. The final model contains 103 residues for each of the five B subunits, 175 residues for the A1 subunit, and 41 residues for the A2 subunit. In this Arg7Lys structure the active site cleft within the A subunit is wider by approximately 1 A than is seen in the wild-type LT. Furthermore, a loop near the active site consisting of residues 47-56 is disordered in the Arg7Lys structure, even though the new lysine residue at position 7 assumes a position which virtually coincides with that of Arg7 in the wild-type structure. The displacement of residues 47-56 as seen in the mutant structure is proposed to be necessary for allowing NAD access to the active site of the wild-type LT. On the basis of the differences observed between the wild-type and Arg7Lys structures, we propose a model for a coordinated sequence of conformational changes required for full activation of LT upon reduction of disulfide bridge 187-199 and cleavage of the peptide loop between the two cysteines in the A subunit.(ABSTRACT TRUNCATED AT 250 WORDS)

The Arg7Lys mutant of heat-labile enterotoxin exhibits great flexibility of active site loop 47-56 of the A subunit.,van den Akker F, Merritt EA, Pizza M, Domenighini M, Rappuoli R, Hol WG Biochemistry. 1995 Sep 5;34(35):10996-1004. PMID:7669757<ref>PMID:7669757</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

<references/>

[[Category: Bacillus coli migula 1895]]

[[Category: Hol, W G.J]]

[[Category: Enterotoxin]]