CLONING OF THE ALDEHYDE REDUCTASE GENE FROM A RED YEAST, SPOROBOLOMYCES SALMONICOLOR, AND CHARACTERIZATION OF THE GENE AND ITS PRODUCT

An NADPH-dependent aldehyde reductase (ALR) isolated from a red yeast, Sporobolomyces salmonicolor, catalyzes the reduction of a variety of carbonyl compounds. To investigate its primary structure, we cloned an d sequenced the cDNA coding for ALR. The aldehyde reductase gene (ALR) comprises 969 bp and encodes a polypeptide of 35,232 Da. The deduced amino acid sequence showed a high degree of similarity to other member s of the aldo-keto reductase superfamily. Analysis of the genomic DNA sequence indicated that the ALR gene was interrupted by six introns (t wo in the 5' noncoding region and four in the coding region). Southern hybridization analysis of the genomic DNA from S. salmonicolor indica ted that there was one copy of the gene. The ALR gene was expressed in Escherichia coli under the control of the tac promoter. The enzyme ex pressed in E. coli was purified to homogeneity and showed the same cat alytic properties as did the enzyme from S. salmonicolor.