Breunig K D
Institut für Mikrobiologie, Universität Düsseldorf, Federal Republic of Germany.
Mol Gen Genet. 1989 Apr;216(2-3):422-7. doi: 10.1007/BF00334386.
In the yeast Kluyveromyces lactis the beta-galactosidase gene is induced by lactose or galactose. As shown here it can also be repressed by glucose but only in some strains. When the LAC9 gene of a repressible strain is substituted by an allele of a non-repressible strain, the beta-galactosidase gene is no longer glucose repressed. LAC9 codes for a regulatory protein homologous to GAL4 which activates transcription in the presence of the inducer. Since the LAC9 product is also present in the repressed strain and binds to DNA in vitro, as shown by DNA footprinting, glucose repression cannot be caused by repression of LAC9 gene expression. Instead, our results demonstrate that glucose repression is mediated by the LAC9 gene product, and is separable from the ability of LAC9 to activate transcription.
在乳酸克鲁维酵母中，β-半乳糖苷酶基因可被乳糖或半乳糖诱导。如本文所示，它也可被葡萄糖抑制，但仅在某些菌株中。当可抑制菌株的LAC9基因被不可抑制菌株的等位基因取代时，β-半乳糖苷酶基因不再受葡萄糖抑制。LAC9编码一种与GAL4同源的调节蛋白，该蛋白在诱导剂存在时激活转录。由于LAC9产物也存在于受抑制的菌株中，并且如DNA足迹分析所示，它在体外与DNA结合，因此葡萄糖抑制不可能是由LAC9基因表达的抑制引起的。相反，我们的结果表明，葡萄糖抑制是由LAC9基因产物介导的，并且与LAC9激活转录的能力是可分离的。
