Gene Identification and Characterization of the Pyridoxine Degradative Enzyme α-(N-Acetylaminomethylene)succinic Acid Amidohydrolase from Mesorhizobium loti MAFF303099

Baiqiang YUAN; Nana YOKOCHI; Yu YOSHIKANE; Kouhei OHNISHI; Fei GE; Toshiharu YAGI

doi:10.3177/jnsv.54.185

Regular Paper

Gene Identification and Characterization of the Pyridoxine Degradative Enzyme α-(N-Acetylaminomethylene)succinic Acid Amidohydrolase from Mesorhizobium loti MAFF303099

Baiqiang YUAN, Nana YOKOCHI, Yu YOSHIKANE, Kouhei OHNISHI, Fei GE, Toshiharu YAGI

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Keywords: vitamin B₆, pyridoxine, degradation pathway, α-(N-acetylaminomethylene)succinic acid, amidohydrolase

JOURNAL FREE ACCESS

2008 Volume 54 Issue 3 Pages 185-190

DOI https://doi.org/10.3177/jnsv.54.185

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Abstract

We have found for the first time that a chromosomal gene, mlr6787, in Mesorhizobium loti encodes the pyridoxine degradative enzyme α-(N-acetylaminomethylene)succinic acid (AAMS) amidohydrolase. The recombinant enzyme expressed in Escherichia coli cells was homogeneously purified and characterized. The enzyme consisted of two subunits each with a molecular mass of 34,000±1,000 Da, and exhibited Km and kcat values of 53.7±6 μM and 307.3±12 min⁻¹, respectively. The enzyme required no cofactor or metal ion. The primary structure of AAMS amidohydrolase was elucidated for the first time here. The primary structure of the enzyme protein showed no significant identity to those of known hydrolase proteins and low homology to those of fluoroacetate dehalogenase (PDB code, 1Y37), haloalkane dehalogenase (1K5P), and aryl esterase (1VA4).

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