Maize glutathione-dependent formaldehyde dehydrogenase cDNA: a novel plant gene of detoxification.

摘要

It has been previously shown that intact plants and cultured plant cells can metabolize and detoxify formaldehyde through the action of a glutathione-dependent formaldehyde dehydrogenase (FDH), followed by C-1 metabolism of the initial metabolite (formic acid). Here, the cloning and heterologous expression of a cDNA for the glutathione-dependent formaldehyde dehydrogenase from Zea mays is described. The functional expression of the maize cDNA in Escherichia coli proved that the cloned enzyme catalyses the NAD+- and glutathione (GSH)-dependent oxidation of formaldehyde. The deduced amino acid sequence of 41 kDa was on average 65% identical with class III alcohol dehydrogenases from animals and less than 60% identical with conventional plant alcoholdehydrogenases (ADH) utilizing ethanol. Genomic analysis suggested the existence of a single gene for this cDNA. Phylogenetic analysis supports the convergent evolution of ethanol-consuming ADHs in animals and plants from formaldehyde-detoxifying ancestors. The high structural conservation of present-day glutathione-dependent FDH in microorganisms, plants and animals is consistent with a universal importance of these detoxifying enzymes. Nucleotide sequence data have been submitted to the EMBL/GenBank/DDBJ databases under the accession number Y11029.