PDBsum entry: 1jf8

Oxidoreductase

PDB id: 1jf8

Contents

Protein chain

130 a.a. *

Ligands

BCT

TRS

Metals

__K

Waters ×220

* Residue conservation analysis

PDB id:

1jf8

Name:

Oxidoreductase

Title:

X-ray structure of reduced c10s, c15a arsenate reductase from pi258

Structure:

Arsenate reductase. Chain: a. Synonym: arsenical pump modifier. Engineered: yes. Mutation: yes

Source:

Staphylococcus aureus. Organism_taxid: 1280. Gene: arsc. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.12Å R-factor: 0.208 R-free: 0.227

Authors:

I.Zegers,J.C.Martins,R.Willem,L.Wyns,J.Messens

Key ref:

I.Zegers et al. (2001). Arsenate reductase from S. aureus plasmid pI258 is a phosphatase drafted for redox duty. Nat Struct Biol, 8, 843-847. PubMed id: 11573087 DOI: 10.1038/nsb1001-843

Date:

20-Jun-01 Release date: 03-Oct-01

Protein chain

P0A006  (ARSC_STAAU) -  Protein ArsC

Seq: 131 a.a.

Struc: 130 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.1.3.48 - Protein-tyrosine-phosphatase.
• Reaction: Protein tyrosine phosphate + H₂O = protein tyrosine + phosphate

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

 Gene Ontology (GO) functional annotation 

• Biological process: oxidation reduction (3 terms)
• Biochemical function: oxidoreductase activity (4 terms)

reference

DOI no: 10.1038/nsb1001-843

Nat Struct Biol 8:843-847 (2001)

PubMed id: 11573087

Arsenate reductase from S. aureus plasmid pI258 is a phosphatase drafted for redox duty.

I.Zegers, J.C.Martins, R.Willem, L.Wyns, J.Messens.

ABSTRACT

Arsenate reductase (ArsC) from Staphylococcus aureus plasmid pI258 plays a role in bacterial heavy metal resistance and catalyzes the reduction of arsenate to arsenite. The structures of the oxidized and reduced forms of ArsC were solved. ArsC has the PTPase I fold typical for low molecular weight tyrosine phosphatases (LMW PTPases). Remarkably, kinetic experiments show that pI258 ArsC also catalyzes the tyrosine phosphatase reaction in addition to arsenate reduction. These results provide evidence that ArsC from pI258 evolved from LMW PTPase by the grafting of a redox function onto a pre-existing catalytic site and that its evolutionary origin is different from those of arsenate reductases from Escherichia coli plasmid R773 and from Saccharomyces cerevisiae. The mechanism proposed here for the catalysis of arsenate reduction by pI258 ArsC involves a nucleophilic attack by Cys 10 on arsenate, the formation of a covalent intermediate and the transport of oxidative equivalents by a disulfide cascade. The reaction is associated with major structural changes in the ArsC.

Selected figure(s)

Figure 1.
Figure 1. The structure of pI258 ArsC. a, Overall structure of the reduced form of arsenate reductase. The catalytic site region is shown in red, and the part of the protein involved in the redox function in yellow. The area of ArsC corresponding to the Tyr binding site in LMW PTPase is shown in green. b, 2F[o] - F[c] electron density map in the region of the active site of the reduced form of ArsC at 1.1 Å resolution. The map shows a carbonate bound to the P-loop and the electron density for the Cys 82 sulfinic acid, and is contoured at 1.5 . c, 2F[o] - F[c] electron density map in the region of the Cys 82 -Cys 89 disulfide bond in the oxidized form of ArsC at 2.0 Å resolution. The map is contoured at 1.0 . d, The active site of the oxidized form of ArsC (ArsC-ox, orange) is superimposed on that of the reduced form of ArsC (ArsC-red, blue). For the structure of ArsC-red, the carbonate, Tris, Cys 82, Cys 89 and residues from a hydrophobic core surrounding Cys 89 are shown. For ArsC-ox, Cys 82 and Cys 89 and the perchlorate are shown. e, Mapping of ArsC-red residues whose amide correlation peaks either disappear (blue) or are significantly perturbed ( (1H) > 0.04 p.p.m. and (15N) > 0.27 p.p.m.; red) when 50 mM K[2]SO[4] is removed from the NMR solution by dialysis against phosphate only buffer. Secondary structure elements are highlighted in green (helices) and yellow (sheets). f, Superposition of the active site region of ArsC-red with a bound carbonate (blue) on the active site region of human LMW tyrosine phosphatase (green), including a 2-(N-morholino)ethanesulfonic acid (MES) molecule bound to the Tyr binding site. g, CPK model of ArsC-ox. Cys side chains are shown in yellow; side chains of hydrophobic residues, green; side chain oxygens of Asp and Glu, red; and side chains nitrogens of Lys and Arg, blue.

Figure 3.
Figure 3. Catalytic mechanism of pI258 ArsC. a, Reaction scheme for the reaction catalyzed by LMW PTPases14. b, Reaction scheme proposed for the reduction of arsenate by S. aureus pI258 ArsC. The reaction starts with a nucleophilic attack of Cys 10 on an arsenate, leading to the formation of a covalent intermediate. For the next steps, we propose a disulfide cascade that brings about the reduction of the arsenic (V) to arsenic (III). Cys 82 can attack Cys 10, forming an intermediate Cys 10 -Cys 82 disulfide bond. Cys 10 can donate an electron pair to the arsenic. Cys 89 can then attack Cys 82, regenerating Cys 10 and forming a Cys 82 -Cys 89 disulfide bond, as found in ArsC-ox.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2001, 8, 843-847) copyright 2001.

Figures were selected by the author.