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Arsenate Reductase (arsenate + reductase)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

Identification of a triad of arginine residues in the active site of the ArsC arsenate reductase of plasmid R773

FEMS MICROBIOLOGY LETTERS, Issue 2 2003
Jin Shi
Abstract ArsC from plasmid R773 catalyzes reduction of arsenate in Escherichia coli. Arg-60, Arg-94 and Arg-107 are near the active site residue Cys-12, suggesting that they form an anion binding pocket in the active site and/or participate in catalysis. These three arginine residues were altered to a variety of other residues by site-directed mutagenesis. Only mutants with arginine-to-lysine substitutions conferred arsenate resistance in vivo, although purified R60A, R60E, R60K exhibited varying levels of enzymatic activity. The data support the hypothesis that this triad of arginine residues is involved in arsenate binding and transition-state stabilization. [source]

NMR structure of the enzyme GatB of the galactitol-specific phosphoenolpyruvate-dependent phosphotransferase system and its interaction with GatA

PROTEIN SCIENCE, Issue 10 2006
Laurent Volpon
Abstract The phosphoenolpyruvate-dependent carbohydrate transport system (PTS) couples uptake with phosphorylation of a variety of carbohydrates in prokaryotes. In this multienzyme complex, the enzyme II (EII), a carbohydrate-specific permease, is constituted of two cytoplasmic domains, IIA and IIB, and a transmembrane channel IIC domain. Among the five families of EIIs identified in Escherichia coli, the galactitol-specific transporter (IIgat) belongs to the glucitol family and is structurally the least well-characterized. Here, we used nuclear magnetic resonance (NMR) spectroscopy to solve the three-dimensional structure of the IIB subunit (GatB). GatB consists of a central four-stranded parallel ,-sheet flanked by ,-helices on both sides; the active site cysteine of GatB is located at the beginning of an unstructured loop between ,1 and ,1 that folds into a P-loop-like structure. This structural arrangement shows similarities with other IIB subunits but also with mammalian low molecular weight protein tyrosine phosphatases (LMW PTPase) and arsenate reductase (ArsC). An NMR titration was performed to identify the GatA-interacting residues. [source]

The structure of a triple mutant of pI258 arsenate reductase from Staphylococcus aureus and its 5-­thio-2-nitrobenzoic acid adduct

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2004
Joris Messens
Structural insights into formation of the complex between the ubiquitous thiol,disulfide oxidoreductase thioredoxin and its oxidized substrate are under-documented owing to its entropical instability. In vitro, it is possible via a reaction with 5,5,-dithiobis-(2-­nitrobenzoic acid) to make a stable mixed-disulfide complex between thioredoxin from Staphylococcus aureus and one of its substrates, oxidized pI258 arsenate reductase (ArsC) from S. aureus. In the absence of the crystal structure of an ArsC,thioredoxin complex, the structures of two precursors of the complex, the ArsC triple mutant ArsC C10SC15AC82S and its 5-thio-2-nitrobenzoic acid (TNB) adduct, were determined. The ArsC triple mutant has a structure very similar to that of the reduced form of wild-type ArsC, with a folded redox helix and a buried catalytic Cys89. In the adduct form, the TNB molecule is buried in a hydrophobic pocket and the disulfide bridge between TNB and Cys89 is sterically inaccessible to thioredoxin. In order to form a mixed disulfide between ArsC and thioredoxin, a change in the orientation of the TNB,Cys89 disulfide in the structure is necessary. [source]