Heterologous expression of human 5-aminolevulinate dehydratase in Saccharomyces cerevisiae

A cDNA coding for human 5-amino-levulinate dehydratase was placed in a yeast expression vector under the control of the GAL10 promoter. The resulting multicopy plasmid was then used to transform a yeast mutant which contains a defective hem2 gene coding for 5-aminolevulinate dehydratase. Expression of the human cDNA was shown in four ways: (1) restoration of normal growth on glycerol/galactose as primary carbon source, (2) decrease in intracellular 5-aminolevulinic acid concentration, (3) restoration of cytochrome biosynthesis and (4) direct, in situ assay of 5-aminolevulinic acid dehydratase. Curing transformed cells of plasmid restored the hem2 mutant phenotype. This heterologous system could be used to produce large quantities of human 5-aminolevulinic acid dehydratase for physical and biochemical studies.