Characterization and metabolic function of a peroxisomal sarcosine and pipecolate oxidase from Arabidopsis.

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Goyer A, Johnson TL, Olsen LJ, Collakova E, Shachar-Hill Y, Rhodes D, Hanson AD

Characterization and metabolic function of a peroxisomal sarcosine and pipecolate oxidase from Arabidopsis.

J Biol Chem. 2004 Apr 23;279(17):16947-53. doi: 10.1074/jbc.M400071200. Epub 2004 Feb 6.

PubMed ID

14766747 [ View in PubMed

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Abstract

Sarcosine oxidase (SOX) is known as a peroxisomal enzyme in mammals and as a sarcosine-inducible enzyme in soil bacteria. Its presence in plants was unsuspected until the Arabidopsis genome was found to encode a protein (AtSOX) with approximately 33% sequence identity to mammalian and bacterial SOXs. When overexpressed in Escherichia coli, AtSOX enhanced growth on sarcosine as sole nitrogen source, showing that it has SOX activity in vivo, and the recombinant protein catalyzed the oxidation of sarcosine to glycine, formaldehyde, and H(2) O(2) in vitro. AtSOX also attacked other N-methyl amino acids and, like mammalian SOXs, catalyzed the oxidation of l-pipecolate to Delta(1)-piperideine-6-carboxylate. Like bacterial monomeric SOXs, AtSOX was active as a monomer, contained FAD covalently bound to a cysteine residue near the C terminus, and was not stimulated by tetrahydrofolate. Although AtSOX lacks a typical peroxisome-targeting signal, in vitro assays established that it is imported into peroxisomes. Quantitation of mRNA showed that AtSOX is expressed at a low level throughout the plant and is not sarcosine-inducible. Consistent with a low level of AtSOX expression, Arabidopsis plantlets slowly metabolized supplied [(14)C]sarcosine to glycine and serine. Gas chromatography-mass spectrometry analysis revealed low levels of pipecolate but almost no sarcosine in wild type Arabidopsis and showed that pipecolate but not sarcosine accumulated 6-fold when AtSOX expression was suppressed by RNA interference. Moreover, the pipecolate catabolite alpha-aminoadipate decreased 30-fold in RNA interference plants. These data indicate that pipecolate is the endogenous substrate for SOX in plants and that plants can utilize exogenous sarcosine opportunistically, sarcosine being a common soil metabolite.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Glycine	Peroxisomal sarcosine oxidase	Protein	Humans	Unknown	Product of	Details