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首页> 外文期刊>Molecular and Cellular Biology >Characterization of a positive regulatory gene, LAC9, that controls induction of the lactose-galactose regulon of Kluyveromyces lactis: structural and functional relationships to GAL4 of Saccharomyces cerevisiae.
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Characterization of a positive regulatory gene, LAC9, that controls induction of the lactose-galactose regulon of Kluyveromyces lactis: structural and functional relationships to GAL4 of Saccharomyces cerevisiae.

机译：阳性调控基因，LAC9的表征，对kluyveromyces乳房乳糖 - 半乳糖调节件的诱导：结构和功能关系与酿酒酵母的Gal4。

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Lactose or galactose induces the expression of the lactose-galactose regulon in Kluyveromyces lactis. We show here that the regulon is not induced in strains defective in LAC9. We demonstrate that this gene codes for a regulatory protein that acts in a positive manner to induce transcription. The LAC9 gene was isolated by complementation of a lac9 defective strain. DNA sequence analysis of the gene gave a deduced protein of 865 amino acids. Comparison of this sequence with that of the GAL4 protein of Saccharomyces cerevisiae revealed three regions of homology. One region of about 90 amino acid occurs at the amino terminus, which is known to mediate binding of GAL4 protein to upstream activator sequences. We speculate that a portion of this region, adjacent to the "metal-binding finger," specifies DNA binding. We discuss possible functions of the two other regions of homology. The functional implications of these structural similarities were examined. When LAC9 was introduced into a gal4 defective strain of S. cerevisiae it complemented the mutation and activated the galactose-melibiose regulon. However, LAC9 did not simply mimic GAL4. Unlike normal S. cerevisiae carrying GAL4, the strain carrying LAC9 gave constitutive expression of GAL1 and MEL1, two genes in the regulon. The strain did show glucose repression of the regulon, but repression was less severe with LAC9 than with GAL4. We discuss the implications of these results and how they may facilitate our understanding of the LAC9 and GAL4 regulatory proteins.
机译：乳糖或半乳糖诱导乳糖 - 半乳糖调节件在Kluyveromyces乳房的表达。我们在此显示，调节件在LAC9中的菌株中未诱导。我们证明该基因代码用于一种以阳性方式诱导转录的调节蛋白。通过Lac9缺陷菌株的互补分离LAC9基因。基因的DNA序列分析给出了865个氨基酸的推导蛋白。这种序列与酿酒酵母的Gal4蛋白质的比较揭示了三个同源性的区域。在氨基末端发生约90个氨基酸的一个区域，已知已知将Gal4蛋白与上游活化剂序列的结合介导。我们推测该区域的一部分，与“金属结合手指”相邻，指定DNA结合。我们讨论了另外两个同源地区的可能功能。检查了这些结构相似之处的功能含义。当LAC9被引入GAL4缺陷的S.Cerevisiae的缺陷菌株时，它补充了突变并活化了半乳糖 - Melibiose Condonon。然而，Lac9并没有简单地模仿Gal4。与携带GAL4的正常的S.酿酒酵母不同，携带LAC9的菌株在调节件中含有GAL1和MEL1，两个基因的组成型表达。该菌株确实显示了调节件的葡萄糖抑制，但LAC9的抑制比与GAL4更严重。我们讨论了这些结果的含义以及它们如何促进我们对LAC9和GAL4调节蛋白的理解。

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