1S5B

Cholera holotoxin with an A-subunit Y30S mutation Form 3

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.13 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.177 
  • R-Value Observed: 0.180 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history. 


Literature

Crystal structures of an intrinsically active cholera toxin mutant yield insight into the toxin activation mechanism

O'Neal, C.J., Amaya, E.I., Jobling, M.G., Holmes, R.K., Hol, W.G.

(2004) Biochemistry 43: 3772-3782

  • DOI: 10.1021/bi0360152
  • Primary Citation of Related Structures:  
    1S5F, 1S5E, 1S5D, 1S5C, 1S5B

  • PubMed Abstract: 

    • Cholera toxin (CT) is a heterohexameric bacterial protein toxin belonging to a larger family of A/B ADP-ribosylating toxins. Each of these toxins undergoes limited proteolysis and/or disulfide bond reduction to form the enzymatically active toxic fragment ...

    Cholera toxin (CT) is a heterohexameric bacterial protein toxin belonging to a larger family of A/B ADP-ribosylating toxins. Each of these toxins undergoes limited proteolysis and/or disulfide bond reduction to form the enzymatically active toxic fragment. Nicking and reduction render both CT and the closely related heat-labile enterotoxin from Escherichia coli (LT) unstable in solution, thus far preventing a full structural understanding of the conformational changes resulting from toxin activation. We present the first structural glimpse of an active CT in structures from three crystal forms of a single-site A-subunit CT variant, Y30S, which requires no activational modifications for full activity. We also redetermined the structure of the wild-type, proenzyme CT from two crystal forms, both of which exhibit (i) better geometry and (ii) a different A2 "tail" conformation than the previously determined structure [Zhang et al. (1995) J. Mol. Biol. 251, 563-573]. Differences between wild-type CT and active CTY30S are observed in A-subunit loop regions that had been previously implicated in activation by analysis of the structure of an LT A-subunit R7K variant [van den Akker et al. (1995) Biochemistry 34, 10996-11004]. The 25-36 activation loop is disordered in CTY30S, while the 47-56 active site loop displays varying degrees of order in the three CTY30S structures, suggesting that disorder in the activation loop predisposes the active site loop to a greater degree of flexibility than that found in unactivated wild-type CT. On the basis of these six new views of the CT holotoxin, we propose a model for how the activational modifications experienced by wild-type CT are communicated to the active site.

    Organizational Affiliation: 

    Department of Chemistry and Biomolecular Structure Center, University of Washington, Seattle, Washington 98195, USA.



Macromolecules
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(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Cholera enterotoxin, A chain precursor A240Vibrio choleraeMutation(s): 1 
Gene Names: ctxA, toxA, VC1457
EC: 2.4.2.36 (PDB Primary Data), 2.4.2 (UniProt)
Find proteins for P01555 (Vibrio cholerae serotype O1 (strain ATCC 39315 / El Tor Inaba N16961))
Explore P01555 
Go to UniProtKB:  P01555
Protein Feature View
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  • Reference Sequence
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
cholera toxin B protein (CTB) D, E, F, G, H103Vibrio choleraeMutation(s): 0 
Gene Names: ctxB, toxB, VC1456
Find proteins for P01556 (Vibrio cholerae serotype O1 (strain ATCC 39315 / El Tor Inaba N16961))
Explore P01556 
Go to UniProtKB:  P01556
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA
Download Ideal Coordinates CCD File 
A
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.13 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.177 
  • R-Value Observed: 0.180 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.104α = 90
b = 107.431β = 91.29
c = 65.95γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
HKL-2000data reduction
SCALEPACKdata scaling
MOLREPphasing

Structure Validation

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View more in-depth experimental data

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-04-06
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Version format compliance