title: Construction of strains of Saccharomyces cerevisiae that grow on lactose.
abstract: We have constructed strains of Saccharomyces cerevisiae that grow on lactose (Lac+). S. cerevisiae strain YNN27, which, like all S. cerevisiae, is unable to grow on lactose, was transformed with pKR1B-LAC4-1. This plasmid has a selectable marker gene conferring resistance to the antibiotic G418 and carries a 13-kilobase region of the Kluyveromyces lactis genome including LAC4, a beta-galactosidase gene. Transformants were selected first for G418 resistance and then for growth on lactose. Southern hybridization experiments showed that Lac+ transformants had integrated 15-25 tandem copies of the vector into a host chromosome. Several lines of evidence indicate that the Lac+ phenotype in pKR1B-LAC4-1-transformed S. cerevisiae is due to expression of a K. lactis lactose permease gene that lies between 2 and 8.6 kilobase upstream of LAC4 and also to expression of LAC4. The permease gene has been designated LAC12.
mesh_terms: D001693:Biological Transport, Active; D002874:Chromosome Mapping; D029968:Escherichia coli Proteins; D005800:Genes, Fungal; D005818:Genetic Engineering; D007716:Kluyveromyces / Q000235:genetics; D007785:Lactose / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics*; D009004:Monosaccharide Transport Proteins; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D027981:Symporters; D014170:Transformation, Genetic; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D027981:Symporters; C021499:lactose permease; D001616:beta-Galactosidase; D007785:Lactose