Woods A, Munday M R, Scott J, Yang X, Carlson M, Carling D
Medical Research Council of Molecular Medicine, Royal Postgraduate Medical School, London, United Kingdom.
J Biol Chem. 1994 Jul 29;269(30):19509-15.
The product of the SNF1 gene is a protein kinase whose activity is essential for transcriptional activation of glucose repressed genes in Saccharomyces cerevisiae. We have cloned a mammalian AMP-activated protein kinase (AMPK) that is 46% identical to the deduced amino acid sequence of SNF1 (Carling, D., Aguan, K., Woods, A., Verhoeven, A.J.M., Beri, R., Brennan, C.H., Sidebottom, C., Davison, M.D., and Scott, J. (1994) J. Biol. Chem. 269, 11442-11448). Mammalian AMPK plays a major role in the control of lipid metabolism and phosphorylating, thereby inactivating both acetyl-CoA carboxylase and 3-hydroxy-3-methylglutaryl-CoA reductase, key regulatory enzymes in the synthesis of fatty acids and cholesterol, respectively. We present evidence indicating that, in common with its mammalian homologue, SNF1 forms part of a protein kinase cascade. SNF1 is inactivated in vitro by treatment with protein phosphatase 2A and can be reactivated using a partially purified preparation of mammalian AMPK kinase. SNF1 undergoes a time-dependent increase in activity during growth in glucose-derepressing conditions, providing the first evidence that SNF1 activity is regulated by the level of available glucose. In wild-type yeast, but not in a snf1 deletion mutant, acetyl-CoA carboxylase shows a reciprocal change in activity compared with SNF1 under glucose derepressing conditions, indicating that SNF1 regulates acetyl-CoA carboxylase in vivo. These results suggest that, in addition to their structural similarity, the role of SNF1 and AMPK in the regulation of fatty acid synthesis has been highly conserved throughout evolution.
SNF1基因的产物是一种蛋白激酶，其活性对于酿酒酵母中葡萄糖抑制基因的转录激活至关重要。我们克隆了一种哺乳动物的AMP激活蛋白激酶（AMPK），它与SNF1推导的氨基酸序列有46%的同源性（卡林，D.，阿关，K.，伍兹，A.，韦霍温，A.J.M.，贝里，R.，布伦南，C.H.，赛德博特姆，C.，戴维森，M.D.，和斯科特，J.（1994年）《生物化学杂志》269卷，11442 - 11448页）。哺乳动物的AMPK在脂质代谢控制中起主要作用，通过磷酸化使乙酰辅酶A羧化酶和3 - 羟基 - 3 - 甲基戊二酰辅酶A还原酶失活，这两种酶分别是脂肪酸和胆固醇合成中的关键调节酶。我们提供的证据表明，与它的哺乳动物同源物一样，SNF1是蛋白激酶级联反应的一部分。用蛋白磷酸酶2A处理后，SNF1在体外失活，并且可以用部分纯化的哺乳动物AMPK激酶制剂使其重新激活。在葡萄糖去阻遏条件下生长期间，SNF1的活性随时间增加，这首次证明SNF1的活性受可用葡萄糖水平的调节。在野生型酵母中，而不是在snf1缺失突变体中，在葡萄糖去阻遏条件下，乙酰辅酶A羧化酶的活性与SNF1呈现相反的变化，表明SNF1在体内调节乙酰辅酶A羧化酶。这些结果表明，除了结构相似性外，SNF1和AMPK在脂肪酸合成调节中的作用在整个进化过程中高度保守。
