PMID:12773527

Citation	Oinuma, K, Hashimoto, Y, Konishi, K, Goda, M, Noguchi, T, Higashibata, H and Kobayashi, M (2003) Novel aldoxime dehydratase involved in carbon-nitrogen triple bond synthesis of Pseudomonas chlororaphis B23. Sequencing, gene expression, purification, and characterization. J. Biol. Chem. 278:29600-8
Abstract	Analysis of the nitrile hydratase gene cluster involved in nitrile metabolism of Pseudomonas chlororaphis B23 revealed that it contains one open reading frame encoding aldoxime dehydratase upstream of the amidase gene. The amino acid sequence deduced from this open reading frame shows similarity (32% identity) with that of Bacillus phenylacetaldoxime dehydratase (Kato, Y., Nakamura, K., Sakiyama, H., Mayhew, S. G., and Asano, Y. (2000) Biochemistry 39, 800-809). The gene product expressed in Escherichia coli catalyzed the dehydration of aldoxime into nitrile. The Pseudomonas aldoxime dehydratase (OxdA) was purified from the E. coli transformant and characterized. OxdA shows an absorption spectrum with a Soret peak that is characteristic of heme, demonstrating that it is a hemoprotein. For its activity, this enzyme required a reducing reagent, Na2S2O4, but did not require FMN, which is crucial for the Bacillus enzyme. The enzymatic reaction was found to be catalyzed when the heme iron of the enzyme was in the ferrous state. Calcium as well as iron was included in the enzyme. OxdA reduced by Na2S2O4 had a molecular mass of 76.2 kDa and consisted of two identical subunits. The kinetic parameters of OxdA indicated that aliphatic aldoximes are more effective substrates than aromatic aldoximes. A variety of spectral shifts in the absorption spectra of OxdA were observed upon the addition of each of various compounds (i.e. redox reagents and heme ligands). Moreover, the addition of the substrate to OxdA gave a peak that would be derived from the intermediate in the nitrile synthetic reaction. P. chlororaphis B23 grew and showed the OxdA activity when cultured in a medium containing aldoxime as the sole carbon and nitrogen source. Together with these findings, Western blotting analysis of the extracts using anti-OxdA antiserum revealed that OxdA is responsible for the metabolism of aldoxime in vivo in this strain.
Links	PubMed Online version:10.1074/jbc.M211832200
Keywords	Amino Acid Sequence; Bacillus/metabolism; Base Sequence; Blotting, Western; Carbon/chemistry; Catalysis; Cell-Free System; DNA/metabolism; Electrophoresis, Polyacrylamide Gel; Escherichia coli/metabolism; Heme/chemistry; Hydro-Lyases/genetics; Hydro-Lyases/physiology; Hydrogen-Ion Concentration; Kinetics; Models, Chemical; Molecular Sequence Data; Multigene Family; Nitrogen/chemistry; Open Reading Frames; Oxidation-Reduction; Plasmids/metabolism; Pseudomonas/metabolism; Pseudomonas/physiology; Recombinant Proteins/genetics; Sequence Homology, Amino Acid; Spectrophotometry; Substrate Specificity; Temperature
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ARTAT:A1R5Y5		GO:0018814: phenylacetaldoxime dehydratase activity	ECO:0000314:		F		Figure 5 shows that OxdA activity is inducible when butyraldoxime was used in low concentrations as the sole carbon and nitrogen source. No OxdA activity was observed when sucrose and (NH4)2SO4 were used as the carbon and nitrogen sources.	complete CACAO 4116
9PSED:Q7WSJ4	Contributes to	GO:0034013: aliphatic aldoxime dehydratase activity	ECO:0000314:		F		OxdA encodes for aldoxime dehydratase activity. Figure 3As shows the activity between the purified enzyme, the enzyme with Na2S2O4-reduced, and the enzyme with Na2S2O4-reduced plus CO. As a result, oxdA was shown to have much higher activity in the presence of Na2S2O4. This shows the Na2S2O4 reagent assists in the already present reducing activity.	complete CACAO 4705

References

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