1SK2

ARSENATE REDUCTASE R60A MUTANT +0.4M ARSENATE FROM E. COLI


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.54 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.186 

wwPDB Validation 3D Report Full Report


This is version 1.5 of the entry. See complete history

Literature

Arginine 60 in the ArsC arsenate reductase of E. coli plasmid R773 determines the chemical nature of the bound As(III) product.

DeMel, S.Shi, J.Martin, P.Rosen, B.P.Edwards, B.F.

(2004) Protein Sci. 13: 2330-2340

  • DOI: 10.1110/ps.04787204
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Arsenic is a ubiquitous environmental toxic metal. Consequently, organisms detoxify arsenate by reduction to arsenite, which is then excreted or sequestered. The ArsC arsenate reductase from Escherichia coli plasmid R773, the best characterized arsen ...

    Arsenic is a ubiquitous environmental toxic metal. Consequently, organisms detoxify arsenate by reduction to arsenite, which is then excreted or sequestered. The ArsC arsenate reductase from Escherichia coli plasmid R773, the best characterized arsenic-modifying enzyme, has a catalytic cysteine, Cys 12, in the active site, surrounded by an arginine triad composed of Arg 60, Arg 94, and Arg 107. During the reaction cycle, the native enzyme forms a unique monohydroxyl Cys 12-thiol-arsenite adduct that contains a positive charge on the arsenic. We hypothesized previously that this unstable intermediate allows for rapid dissociation of the product arsenite. In this study, the role of Arg 60 in product formation was evaluated by mutagenesis. A total of eight new structures of ArsC were determined at resolutions between 1.3 A and 1.8 A, with R(free) values between 0.18 and 0.25. The crystal structures of R60K and R60A ArsC equilibrated with the product arsenite revealed a covalently bound Cys 12-thiol-dihydroxyarsenite without a charge on the arsenic atom. We propose that this intermediate is more stable than the monohydroxyarsenite intermediate of the native enzyme, resulting in slow release of product and, consequently, loss of activity.


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, 540 E. Canfield Avenue, Detroit, MI 48201, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Arsenate reductase
A
140Escherichia coliMutation(s): 1 
Gene Names: arsC
EC: 1.20.4.1
Find proteins for P08692 (Escherichia coli)
Go to UniProtKB:  P08692
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

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Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
CS
Query on CS

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Download CCD File 
A
CESIUM ION
Cs
NCMHKCKGHRPLCM-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.54 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.186 
  • Space Group: P 61 2 2
Unit Cell:
Length (Å)Angle (°)
a = 86.440α = 90.00
b = 86.440β = 90.00
c = 116.450γ = 120.00
Software Package:
Software NamePurpose
SHELXL-97refinement
XTALVIEWrefinement
X-GENdata scaling
SHELXphasing
X-GENdata reduction
SHELXmodel building

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-02-15
    Type: Initial release
  • Version 1.1: 2008-04-29
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Derived calculations, Version format compliance
  • Version 1.3: 2017-10-11
    Type: Refinement description
  • Version 1.4: 2018-04-04
    Type: Data collection
  • Version 1.5: 2018-08-29
    Type: Data collection, Source and taxonomy, Structure summary