1LTG

THE ARG7LYS MUTANT OF HEAT-LABILE ENTEROTOXIN EXHIBITS GREAT FLEXIBILITY OF ACTIVE SITE LOOP 47-56 OF THE A SUBUNIT


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Work: 0.178 
  • R-Value Observed: 0.178 

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This is version 1.2 of the entry. See complete history


Literature

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, E.A.Pizza, M.Domenighini, M.Rappuoli, R.Hol, W.G.

(1995) Biochemistry 34: 10996-11004

  • DOI: https://doi.org/10.1021/bi00035a005
  • Primary Citation of Related Structures:  
    1LTG

  • PubMed Abstract: 

    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 We report here the crystal structure of an inactive single-site mutant of LT in which arginine 7 of the A subunit has been replaced by a lysine residue.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)


  • Organizational Affiliation

    Department of Biological Structure and Biochemistry, University of Washington, Seattle, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
HEAT-LABILE ENTEROTOXINA [auth D],
B [auth E],
C [auth F],
D [auth G],
E [auth H]
103Escherichia coliMutation(s): 0 
UniProt
Find proteins for P32890 (Escherichia coli)
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Go to UniProtKB:  P32890
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UniProt GroupP32890
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
HEAT-LABILE ENTEROTOXINF [auth A]191Escherichia coliMutation(s): 0 
UniProt
Find proteins for P06717 (Escherichia coli)
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Go to UniProtKB:  P06717
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UniProt GroupP06717
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  • Reference Sequence
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
HEAT-LABILE ENTEROTOXING [auth C]49Escherichia coliMutation(s): 0 
UniProt
Find proteins for P06717 (Escherichia coli)
Explore P06717 
Go to UniProtKB:  P06717
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UniProt GroupP06717
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.40 Å
  • R-Value Work: 0.178 
  • R-Value Observed: 0.178 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 119.7α = 90
b = 98.5β = 90
c = 65.5γ = 90
Software Package:
Software NamePurpose
XENGENdata collection
X-PLORmodel building
X-PLORrefinement
XENGENdata reduction
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1995-09-15
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance