Ostling J, Ronne H
Department of Medical Immunology and Microbiology, Uppsala University, Uppsala Biomedical Center, Sweden.
Eur J Biochem. 1998 Feb 15;252(1):162-8. doi: 10.1046/j.1432-1327.1998.2520162.x.
Mig1p, a zinc-finger protein that is related to the Krox/Egr, Wilms' tumor and Sp1 proteins, mediates glucose repression in the yeast Saccharomyces cerevisiae. Mig1p is inactive in the absence of glucose, and this inhibition is dependent on the Snf1p (Cat1p) protein kinase. The regulation is mediated by an internal part of Mig1p, and it can be transferred to a Mig1-viral protein 16 (VP16) fusion protein that functions as an activator [Ostling, J., Carlberg, M. & Ronne, H. (1996) Mol. Cell. Biol. 16, 753-761]. We have used Mig1-VP16 to identify three target sites for phosphorylation that mediate Snf1p-dependent inhibition of its activity in the absence of glucose. Two of the sites, Ser278 and Ser311, fit the consensus sequence for phosphorylation by the kinase Snf1p, as determined in vitro. However, a third phosphorylated site, Ser108, does not resemble a Snf1p site. We tested the effect of deleting residues 181-245, which contain two conserved alanine-leucine-serine motifs. We found that the deletion produces a partially constitutive activator, indicating that this region plays a general negative role in regulating Mig1p.
Mig1p是一种与Krox/Egr、威尔姆斯瘤和Sp1蛋白相关的锌指蛋白，介导酿酒酵母中的葡萄糖抑制作用。在没有葡萄糖的情况下，Mig1p处于无活性状态，这种抑制作用依赖于Snf1p（Cat1p）蛋白激酶。这种调节由Mig1p的内部区域介导，并且可以转移到作为激活剂起作用的Mig1-病毒蛋白16（VP16）融合蛋白上[奥斯特林，J.，卡尔伯格，M. & 龙内，H.（1996年）《分子细胞生物学》16，753 - 761]。我们利用Mig1-VP16鉴定出三个磷酸化靶位点，它们在没有葡萄糖的情况下介导Snf1p对其活性的依赖性抑制。其中两个位点，Ser278和Ser311，符合体外测定的激酶Snf1p磷酸化的共有序列。然而，第三个磷酸化位点Ser108并不类似Snf1p位点。我们测试了缺失包含两个保守丙氨酸-亮氨酸-丝氨酸基序的181 - 245位残基的效果。我们发现这种缺失产生了一种部分组成型激活剂，表明该区域在调节Mig1p中起一般的负性作用。
