Gene-expression of a thermostable beta-galactosidase in mammalian-cells and its application in assays of eukaryotic promoter activity

The gene (lacS) encoding a thermostable beta-galactosidase enzyme (Ss beta-gal) from the archaebacterium Sulfolobus solfataricus has been cloned and expressed in simian CV1 and murine NIH3T3 cell lines. The recombinant protein is an active enzyme that shows the same properties of thermophilicity and thermostability as the wild-type Ss beta-gal and has no cytotoxic effect on the host cells. Its possible use as a reporter gene is also proposed, and a comparison with other reporter gene systems is made.