Celenza J L, Carlson M
Department of Genetics and Development, College of Physicians and Surgeons of Columbia University, New York, New York 10032.
Mol Cell Biol. 1989 Nov;9(11):5034-44. doi: 10.1128/mcb.9.11.5034-5044.1989.
The SNF1 gene of Saccharomyces cerevisiae encodes a protein-serine/threonine kinase that is required for derepression of gene expression in response to glucose limitation. We present evidence that the protein kinase activity is essential for SNF1 function: substitution of Arg for Lys in the putative ATP-binding site results in a mutant phenotype. A polyhistidine tract near the N terminus was found to be dispensable. Deletion of the large region C terminal to the kinase domain only partially impaired SNF1 function, causing expression of invertase to be somewhat reduced but still glucose repressible. The function of the SNF4 gene, another component of the regulatory system, was required for maximal in vitro activity of the SNF1 protein kinase. Increased SNF1 gene dosage partially alleviated the requirement for SNF4. C-terminal deletions of SNF1 also reduced dependence on SNF4. Our findings suggest that SNF4 acts as a positive effector of the kinase but does not serve a regulatory function in signaling glucose availability.
酿酒酵母的SNF1基因编码一种蛋白质丝氨酸/苏氨酸激酶，该激酶是响应葡萄糖限制时基因表达去阻遏所必需的。我们提供的证据表明，蛋白激酶活性对于SNF1功能至关重要：在假定的ATP结合位点将赖氨酸替换为精氨酸会导致突变表型。发现N末端附近的多组氨酸序列是可有可无的。激酶结构域C末端大片段的缺失仅部分损害了SNF1功能，导致转化酶的表达有所降低，但仍可被葡萄糖阻遏。调节系统的另一个组分SNF4基因的功能是SNF1蛋白激酶最大体外活性所必需的。增加SNF1基因剂量可部分缓解对SNF4的需求。SNF1的C末端缺失也降低了对SNF4的依赖性。我们的研究结果表明，SNF4作为激酶的正效应物，但在信号传导葡萄糖可用性方面不发挥调节功能。
