1ltg
From Proteopedia
| Line 7: | Line 7: | ||
|ACTIVITY= | |ACTIVITY= | ||
|GENE= | |GENE= | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY= | ||
| + | |RESOURCES=<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://www.ebi.ac.uk/pdbsum/1ltg PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1ltg RCSB]</span> | ||
}} | }} | ||
| Line 26: | Line 29: | ||
[[Category: enterotoxin]] | [[Category: enterotoxin]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 22:07:09 2008'' |
Revision as of 19:07, 30 March 2008
| |||||||
| , resolution 2.4Å | |||||||
|---|---|---|---|---|---|---|---|
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
THE ARG7LYS MUTANT OF HEAT-LABILE ENTEROTOXIN EXHIBITS GREAT FLEXIBILITY OF ACTIVE SITE LOOP 47-56 OF THE A SUBUNIT
Overview
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 We report here the crystal structure of an inactive single-site mutant of LT in which arginine 7 of the A subunit has been replaced by a lysine residue.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)
About this Structure
1LTG is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.
Reference
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
Page seeded by OCA on Sun Mar 30 22:07:09 2008
