title: Expression of a foreign eukaryotic gene in Saccharomyces cerevisiae: beta-galactosidase from Kluyveromyces lactis.
abstract: Three recombinant DNA vectors carrying the beta-galactosidase structural gene, LAC4, from the yeast Kluyveromyces lactis were constructed and transformed into Saccharomyces cerevisiae. All transformants expressed the beta-galactosidase activity of LAC4. However, the level of enzyme activity varied, being highest in cells transformed with vectors which are maintained as multicopy plasmids and lowest in cells transformed with a vector which integrates into chromosomes. Enzyme levels probably reflect gene dosage. LAC4 is very stable when integrated into a chromosome, but unstable when carried on a plasmid. Therefore, stability is a property of the recombinant vector rather than of LAC4, LAC4-coded beta-galactosidase synthesized in either S. cerevisiae or in K. lactis is the same as judged by two-dimensional polyacrylamide gel electrophoresis. However S. cerevisiae transformed with LAC4 cannot grow on lactose, probably because lactose does not enter the cell.
mesh_terms: D003001:Cloning, Molecular; D004247:DNA / Q000302:isolation & purification; D004274:DNA, Recombinant; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D005696:Galactosidases / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D007785:Lactose / Q000378:metabolism; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014170:Transformation, Genetic; D015003:Yeasts / Q000032:analysis / Q000235:genetics; D001616:beta-Galactosidase / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D004274:DNA, Recombinant; D004247:DNA; D005696:Galactosidases; D001616:beta-Galactosidase; D007785:Lactose