Functional homology between the yeast regulatory proteins GAL4 and LAC9: LAC9-mediated transcriptional activation in Kluyveromyces lactis involves protein binding to a regulatory sequence homologous to the GAL4 protein-binding site.
As shown previously, the beta-galactosidase gene of Kluyveromyces lactis is transcriptionally regulated via an upstream activation site (UASL) which contains a sequence homologous to the GAL4 protein-binding site in Saccharomyces cerevisiae (M. Ruzzi, K.D. Breunig, A.G. Ficca, and C.P. Hollenberg, Mol. Cell. Biol. 7:991-997, 1987). Here we demonstrate that the region of homology specifically binds a K. lactis regulatory protein. The binding activity was detectable in protein extracts from wild-type cells enriched for DNA-binding proteins by heparin affinity chromatography. These extracts could be used directly for DNase I and exonuclease III protection experiments. A lac9 deletion strain, which fails to induce the beta-galactosidase gene, did not contain the binding factor. The homology of LAC9 protein with GAL4 (J.M. Salmeron and S. A. Johnston, Nucleic Acids Res. 14:7767-7781, 1986) strongly suggests that LAC9 protein binds directly to UASL and plays a role similar to that of GAL4 in regulating transcription.
Breunig
K D
KD
Institut für Mikrobiologie, Universität Düsseldorf, Federal Republic of Germany.
Kuger
P
P
D004262:DNA Restriction Enzymes; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D005690:Galactose / Q000235:genetics*; D005696:Galactosidases / Q000235:genetics*; D005800:Genes, Fungal; D005809:Genes, Regulator; D007716:Kluyveromyces / Q000235:genetics*; D009154:Mutation; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid; D004718:Saccharomycetales / Q000235:genetics*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000235:genetics*
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D004262:DNA Restriction Enzymes; D003850:Deoxyribonuclease I; D005696:Galactosidases; D001616:beta-Galactosidase; D005690:Galactose