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首页> 外文期刊>Molecular and Cellular Biology >Identification of upstream activator sequences that regulate induction of the beta-galactosidase gene in Kluyveromyces lactis.
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Identification of upstream activator sequences that regulate induction of the beta-galactosidase gene in Kluyveromyces lactis.

机译：鉴定调节乳克鲁维酵母中β-半乳糖苷酶基因诱导的上游激活序列。

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摘要

Transcription of the Kluyveromyces lactis beta-galactosidase gene, LAC4, is inducible by galactose and lactose. We examined the effects of deletion mutations within the LAC4 promoter on the expression of beta-galactosidase activity. The results of these experiments indicate that at least two upstream activator sequences (UAS) mediate maximum induction by galactose. These UAS sequence elements are homologous to UAS that regulate induction of the melibiose-galactose regulon of Saccharomyces cerevisiae. We also show that a synthetic copy of one of the K. lactis UAS restores the inducibility of a deleted, noninducible LAC4 promoter. Since the uninduced or basal level of LAC4 expression was increased in several promoter deletion strains and in deletion strains carrying one or two synthetic UAS, we examined the contribution of the LAC9 positive regulatory protein to this effect. The LAC9 protein is thought to bind to UAS and activate transcription of LAC4 (L.V. Wray, M.M. Witte, R.C. Dickson, and M.I. Riley, Mol. Cell. Biol. 7:1111-1121, 1987). Our results demonstrate that LAC9 protein plays a role in setting the uninduced level of gene expression, but other factors also participate. For example, in a lac9 background a LAC4 promoter deletion mutant with two copies of a synthetic 17-base-pair UAS yields a sevenfold higher level of uninduced LAC4 expression than the same strain with one UAS. These and other data indicate that the basal level of gene expression is strongly influenced by the base sequence of the promoter.
机译：乳酸克鲁维酵母β-半乳糖苷酶基因LAC4的转录可由半乳糖和乳糖诱导。我们检查了LAC4启动子内的缺失突变对β-半乳糖苷酶活性表达的影响。这些实验的结果表明，至少两个上游激活序列（UAS）介导了半乳糖的最大诱导。这些UAS序列元件与调节酿酒酵母的半乳糖-半乳糖调节子的诱导的UAS同源。我们还显示，乳酸克鲁维酵母UAS之一的合成副本可恢复缺失，不可诱导的LAC4启动子的诱导性。由于在数种启动子缺失菌株和携带一种或两种合成UAS的缺失菌株中，LAC4表达的未诱导水平或基础水平增加，因此我们检查了LAC9阳性调节蛋白对该作用的贡献。认为LAC9蛋白结合UAS并激活LAC4的转录（L.V.Wray，M.M.Witte，R.C.Dickson，和M.I.Riley，Mol.Cell.Biol.7：1111-1121，1987）。我们的结果表明，LAC9蛋白在设定基因表达的未诱导水平中起作用，但其他因素也参与其中。例如，在lac9背景中，具有两个拷贝的合成的17个碱基对的UAS的LAC4启动子缺失突变体的未诱导LAC4表达水平比具有一个UAS的相同菌株高七倍。这些和其他数据表明，基因表达的基础水平受启动子碱基序列的强烈影响。

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