Cloning of the putative aldehyde dehydrogenase, aldA, gene from Streptomyces aureofaciens

A Streptomyces aureofaciens gene, gap, encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was previously identified. Hybridization studies suggested the presence of a second gap gene in S. aureofaciens. To clone the gene, S. aureofaciens subgenomic library was screened with an oligonucleotide probe encoding a peptide motif conserved in all GAPDH. 3352 bp positive BamHI fragment was identified, the length of which correlated with the hybridization signal. The nucleotide sequence of the fragment was determined, and analysis of the sequence revealed the presence of three open reading frames (ORF). However, none of the genes coded for GAPDH. All three genes formed an operon, consisting of gene orf251, with a high homology to a conserved gene present only in archaeabacteria, and the aldA and adhA genes homologous to various eukaryotic and prokaryotic aldehyde- and alcohol-dehydrogenases, with maximum homology to the phenylacetaldehyde dehydrogenases and arylalcohol dehydrogenases, respectively.