Galactokinase encoded by GAL1 is a bifunctional protein required for induction of the GAL genes in Kluyveromyces lactis and is able to suppress the gal3 phenotype in Saccharomyces cerevisiae.
We have analyzed a GAL1 mutant (gal1-r strain) of the yeast Kluyveromyces lactis which lacks the induction of beta-galactosidase and the enzymes of the Leloir pathway in the presence of galactose. The data show that the K. lactis GAL1 gene product has, in addition to galactokinase activity, a function required for induction of the lactose system. This regulatory function is not dependent on galactokinase activity, as it is still present in a galactokinase-negative mutant (gal1-209). Complementation studies in Saccharomyces cervisiae show that K. lactis GAL1 and gal1-209, but not gal1-r, complement the gal3 mutation. We conclude that the regulatory function of GAL1 in K. lactis soon after induction is similar to the function of GAL3 in S. cerevisiae.
Institut für Mikrobiologie, Heinrich-Heine-Universität, Düsseldorf, Germany.
J
J
Meyer
A
A
Walker-Jonah
C P
CP
Hollenberg
D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D004790:Enzyme Induction; D029968:Escherichia coli Proteins; D005686:Galactokinase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D005690:Galactose / Q000494:pharmacology; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005838:Genotype; D007716:Kluyveromyces / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D016366:Open Reading Frames; D010641:Phenotype; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D013489:Suppression, Genetic; D027981:Symporters; D001616:beta-Galactosidase / Q000096:biosynthesis
D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D011994:Recombinant Proteins; D027981:Symporters; C021499:lactose permease; D005686:Galactokinase; D001616:beta-Galactosidase; D005690:Galactose