Collart M A, Struhl K
Department of Biological Chemistry, Harvard Medical School, Boston, Massachusetts 02115.
Genes Dev. 1994 Mar 1;8(5):525-37. doi: 10.1101/gad.8.5.525.
The yeast HIS3 TR and TC TATA elements support basal transcription, but only TR can respond to transcriptional activators. Four genes, NOT1(CDC39), NOT2(CDC36), NOT3, NOT4, act as general negative regulators and preferentially affect TC-dependent transcription. Allele-specific suppression, a two-hybrid interaction, and biochemical confractionation suggest that NOT1 and NOT2 are nuclear proteins associated in a discrete, 500-kD complex. NOT4 interacts with NOT1 and NOT3 in the two-hybrid assay, and overexpression of NOT3 or NOT4 suppresses not1 and not2 mutations. Repression by the NOT proteins is not attributable to inhibition of transcriptional activators, does not involve the CYC8/TUP1 negative regulatory complex, and is distinct from repression by nucleosomes or by the SPT4, 5, 6 proteins that affect chromatin structure. We propose that the NOT protein inhibit the basic RNA polymerase II transcription machinery, possibly by affecting TFIID function.
酵母HIS3的TR和TC TATA元件支持基础转录，但只有TR能对转录激活因子作出反应。四个基因，NOT1（CDC39）、NOT2（CDC36）、NOT3、NOT4，作为一般的负调控因子，优先影响依赖TC的转录。等位基因特异性抑制、双杂交相互作用和生化分级分离表明，NOT1和NOT2是与一个离散的500-kD复合物相关的核蛋白。在双杂交试验中，NOT4与NOT1和NOT3相互作用，NOT3或NOT4的过表达抑制not1和not2突变。NOT蛋白的抑制作用并非归因于转录激活因子的抑制，不涉及CYC8/TUP1负调控复合物，且不同于核小体或影响染色质结构的SPT4、5、6蛋白的抑制作用。我们提出，NOT蛋白可能通过影响TFIID功能来抑制基本的RNA聚合酶II转录机制。
