Komachi K, Redd M J, Johnson A D
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Genes Dev. 1994 Dec 1;8(23):2857-67. doi: 10.1101/gad.8.23.2857.
Tup1 and Ssn6 transcriptionally repress a wide variety of genes in yeast but do not appear to bind DNA. We provide genetic and biochemical evidence that the DNA-binding protein alpha 2, a regulator of cell-type-specific genes, recruits the Tup1/Ssn6 repressor by directly interacting with Tup1. This interaction is mediated by a region of Tup1 containing seven copies of the WD repeat, a 40 amino acid motif of unknown function found in many other proteins. We have found that a single WD repeat will interact with alpha 2, indicating that the WD repeat is a protein-protein interaction domain. Furthermore, a fragment of Tup1 containing primarily WD repeats provides at least partial repression in the absence of Ssn6, suggesting that the repeats also mediate interaction between Tup1 and other components of the repression machinery.
Tup1和Ssn6在酵母中对多种基因进行转录抑制，但它们似乎并不结合DNA。我们提供了遗传学和生物化学证据，表明DNA结合蛋白α2（一种细胞类型特异性基因的调节因子）通过与Tup1直接相互作用来招募Tup1/Ssn6阻遏物。这种相互作用由Tup1的一个区域介导，该区域包含七个WD重复序列拷贝，WD重复序列是在许多其他蛋白质中发现的功能未知的40个氨基酸基序。我们发现单个WD重复序列能与α2相互作用，这表明WD重复序列是一种蛋白质-蛋白质相互作用结构域。此外，一个主要包含WD重复序列的Tup1片段在没有Ssn6的情况下能提供至少部分抑制作用，这表明这些重复序列也介导Tup1与阻遏机制其他组分之间的相互作用。
