Enzymes
UniProtKB help_outline | 1,300 proteins |
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Reaction participants Show >> << Hide
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Namehelp_outline
[thioredoxin]-dithiol
Identifier
RHEA-COMP:10698
Reactive part
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- Name help_outline L-cysteine residue Identifier CHEBI:29950 Charge 0 Formula C3H5NOS Positionhelp_outline n SMILEShelp_outline C(=O)(*)[C@@H](N*)CS 2D coordinates Mol file for the small molecule Search links Involved in 127 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline L-cysteine residue Identifier CHEBI:29950 Charge 0 Formula C3H5NOS Positionhelp_outline n+3 SMILEShelp_outline C(=O)(*)[C@@H](N*)CS 2D coordinates Mol file for the small molecule Search links Involved in 127 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline arsenate Identifier CHEBI:48597 Charge -2 Formula AsHO4 InChIKeyhelp_outline DJHGAFSJWGLOIV-UHFFFAOYSA-L SMILEShelp_outline O[As]([O-])([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 9 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,331 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
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Namehelp_outline
[thioredoxin]-disulfide
Identifier
RHEA-COMP:10700
Reactive part
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- Name help_outline L-cystine residue Identifier CHEBI:50058 Charge 0 Formula C6H8N2O2S2 Positionhelp_outline n/n+3 SMILEShelp_outline C([C@@H](N*)CSSC[C@@H](C(=O)*)N*)(=O)* 2D coordinates Mol file for the small molecule Search links Involved in 51 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline arsenite Identifier CHEBI:29242 Charge -1 Formula AsH2O3 InChIKeyhelp_outline AQLMHYSWFMLWBS-UHFFFAOYSA-N SMILEShelp_outline O[As](O)[O-] 2D coordinates Mol file for the small molecule Search links Involved in 8 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H2O Identifier CHEBI:15377 (Beilstein: 3587155; CAS: 7732-18-5) help_outline Charge 0 Formula H2O InChIKeyhelp_outline XLYOFNOQVPJJNP-UHFFFAOYSA-N SMILEShelp_outline [H]O[H] 2D coordinates Mol file for the small molecule Search links Involved in 6,148 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:43848 | RHEA:43849 | RHEA:43850 | RHEA:43851 | |
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Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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All intermediates of the arsenate reductase mechanism, including an intramolecular dynamic disulfide cascade.
Messens J., Martins J.C., Van Belle K., Brosens E., Desmyter A., De Gieter M., Wieruszeski J.-M., Willem R., Wyns L., Zegers I.
The mechanism of pI258 arsenate reductase (ArsC) catalyzed arsenate reduction, involving its P-loop structural motif and three redox active cysteines, has been unraveled. All essential intermediates are visualized with x-ray crystallography, and NMR is used to map dynamic regions in a key disulfid ... >> More
The mechanism of pI258 arsenate reductase (ArsC) catalyzed arsenate reduction, involving its P-loop structural motif and three redox active cysteines, has been unraveled. All essential intermediates are visualized with x-ray crystallography, and NMR is used to map dynamic regions in a key disulfide intermediate. Steady-state kinetics of ArsC mutants gives a view of the crucial residues for catalysis. ArsC combines a phosphatase-like nucleophilic displacement reaction with a unique intramolecular disulfide bond cascade. Within this cascade, the formation of a disulfide bond triggers a reversible "conformational switch" that transfers the oxidative equivalents to the surface of the protein, while releasing the reduced substrate. << Less
Proc. Natl. Acad. Sci. U.S.A. 99:8506-8511(2002) [PubMed] [EuropePMC]
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Arsenate reductase of Staphylococcus aureus plasmid pI258.
Ji G., Garber E.A.E., Armes L.G., Chen C.-M., Fuchs J.A., Silver S.
Arsenate reductase encoded by Staphylococcus aureus arsenic-resistance plasmid pI258 was overproduced in Escherichia coli and purified. The purified enzyme reduced radioactive arsenate to arsenite when coupled to thioredoxin, thioredoxin reductase, and NADPH. NADPH oxidation coupled to arsenate re ... >> More
Arsenate reductase encoded by Staphylococcus aureus arsenic-resistance plasmid pI258 was overproduced in Escherichia coli and purified. The purified enzyme reduced radioactive arsenate to arsenite when coupled to thioredoxin, thioredoxin reductase, and NADPH. NADPH oxidation coupled to arsenate reduction also required thioredoxin and thioredoxin reductase. Glutaredoxin and reduced glutathione did not stimulate arsenate reduction. NADPH oxidation showed Michaelis-Menten kinetics with a Km of 1 microM AsO4(3-) and an apparent Vmax of 200 nmol/min per mg of protein. At high substrate concentration (above 1 mM AsO4(3-), a secondary rise in the reaction rate was observed, with a Km of 2 mM and an apparent Vmax of 450 nmol/min per mg of protein. This secondary rise also occurred upon addition of phosphate or nitrate (which were not substrates for the enzyme). Arsenite (the product of the enzyme), tellurite, and antimonite [Sb(III)] were inhibitors. Selenate (but not selenite or sulfate) was a substrate for reductase-dependent NADPH oxidation, with an apparent Km of 13 mM SeO4(2-). Arsenate reductase was purified as a monomer of 14.5 kDa, consistent with the DNA sequence. Electrospray mass spectrometry showed two molecular masses of 14,810.5 and 14,436.0 Da, suggesting that 70% of the purified protein lacked the N-terminal three amino acids; HPLC coupled to electrospray mass spectroscopy of protease digest products confirmed this conclusion and verified the entire amino acid sequence. << Less
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Arsenate reductase from S. aureus plasmid pI258 is a phosphatase drafted for redox duty.
Zegers I., Martins J.C., Willem R., Wyns L., Messens J.
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 ... >> More
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. << Less
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The essential catalytic redox couple in arsenate reductase from Staphylococcus aureus.
Messens J., Hayburn G., Desmyter A., Laus G., Wyns L.
Arsenate reductase (ArsC) encoded by Staphylococcus aureus arsenic-resistance plasmid pI258 reduces intracellular As(V) (arsenate) to the more toxic As(III) (arsenite), which is subsequently extruded from the cell. ArsC couples to thioredoxin, thioredoxin reductase, and NADPH to be enzymatically a ... >> More
Arsenate reductase (ArsC) encoded by Staphylococcus aureus arsenic-resistance plasmid pI258 reduces intracellular As(V) (arsenate) to the more toxic As(III) (arsenite), which is subsequently extruded from the cell. ArsC couples to thioredoxin, thioredoxin reductase, and NADPH to be enzymatically active. A novel purification method leads to high production levels of highly pure enzyme. A reverse phase method was introduced to systematically analyze and control the oxidation status of the enzyme. The essential cysteinyl residues and redox couple in arsenate reductase were identified by a combination of site-specific mutagenesis and endoprotease-digest mass spectroscopy analysis. The secondary structures, as determined with CD, of wild-type ArsC and its Cys mutants showed a relatively high helical content, independent of the redox status. Mutation of Cys 10, 82, and 89 led to redox-inactive enzymes. ArsC was oxidized in a single catalytic cycle and subsequently digested with endoproteinases ArgC, AspN, and GluC. From the peptide-mass profiles, cysteines 82 and 89 were identified as the redox couple of ArsC necessary to reduce arsenate to arsenite. << Less