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: 2.4 Å
  • R-Value Work: 0.178 

wwPDB Validation 3D Report Full Report


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


  • 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 ...

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 We report here the crystal structure of an inactive single-site mutant of LT in which arginine 7 of the A subunit has been replaced by a lysine residue.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


    Related Citations: 
    • Refined Structure of Escherichia Coli Heat-Labile Enterotoxin, a Close Relative of Cholera Toxin
      Sixma, T.K.,Kalk, K.H.,Van Zanten, B.A.M.,Dauter, Z.,Kingma, J.,Witholt, B.,Hol, W.G.J.
      (1993) J.Mol.Biol. 230: 890
    • Probing the Structure-Activity Relationship of Escherichia Coli Lt-A by Site-Directed Mutagenesis
      Pizza, M.,Domenighini, M.,Hol, W.,Giannelli, V.,Fontana, M.R.,Giuliani, M.M.,Magagnoli, C.,Peppoloni, S.,Manetti, R.,Rappuoli, R.
      (1994) Mol.Microbiol. 14: 51
    • Crystal Structure of a Cholera Toxin-Related Heat-Labile Enterotoxin from E. Coli
      Sixma, T.K.,Pronk, S.E.,Kalk, K.H.,Wartna, E.S.,Van Zanten, B.A.M.,Witholt, B.,Hol, W.G.J.
      (1991) Nature 351: 371


    Organizational Affiliation

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




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
HEAT-LABILE ENTEROTOXIN
D, E, F, G, H
103Escherichia coliGene Names: eltB (ltpB)
Find proteins for P32890 (Escherichia coli)
Go to UniProtKB:  P32890
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
HEAT-LABILE ENTEROTOXIN
A
191Escherichia coliGene Names: eltA (ltpA)
Find proteins for P06717 (Escherichia coli)
Go to UniProtKB:  P06717
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
HEAT-LABILE ENTEROTOXIN
C
49Escherichia coliGene Names: eltA (ltpA)
Find proteins for P06717 (Escherichia coli)
Go to UniProtKB:  P06717
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Work: 0.178 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 119.700α = 90.00
b = 98.500β = 90.00
c = 65.500γ = 90.00
Software Package:
Software NamePurpose
X-PLORrefinement
XENGENdata reduction
X-PLORphasing
XENGENdata collection
X-PLORmodel building

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

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