Myslinski E, Schuster C, Huet J, Sentenac A, Krol A, Carbon P
UPR du CNRS Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance, IBMC, Strasbourg, France.
Nucleic Acids Res. 1993 Dec 25;21(25):5852-8. doi: 10.1093/nar/21.25.5852.
The selenocysteine tRNA(Sec) gene possesses two external promoter elements, one of which is constituted by a strong TATA box. Point mutant analysis performed in this study led to the conclusion that the functional TATA promoter actually encompasses the sequence -34 GGGTATAAAAGG-23. Individual changes at T-31 do not affect transcription much. Position T-29 is less permissive to mutation since transversion to a G, for example, is less well tolerated than at T-31. Interestingly, a double point mutation, converting GG(-33/-32) to TT, causes abrogation of transcription in vivo and severe reduction of transcription in vitro with human TBP. Therefore, data obtained underscore the fact that, in the Xenopus tRNA(Sec), these two Gs are an integral part of the TATA promoter. Gel retardation experiments indicate that the GG to TT substitution, which led human TBP to lose its ability to support efficient transcription in vitro, correlates with the appearance of an altered pattern of retarded complexes. Altogether, the data presented in this report support a model in which TBP interacts directly with the TATA element of the tRNA(Sec) gene, in contrast to the type of interaction proposed for classical TATA-less tRNA genes.
硒代半胱氨酸转运RNA（Sec）基因拥有两个外部启动子元件，其中一个由一个强TATA框构成。本研究中进行的点突变分析得出结论，功能性TATA启动子实际上包含序列-34 GGGTATAAAAGG-23。T-31位点的单个变化对转录影响不大。T-29位点对突变的耐受性较低，例如，与T-31位点相比，突变为G时的耐受性较差。有趣的是，一个将GG（-33/-32）转换为TT的双点突变，导致体内转录被消除，体外与人TBP结合时转录严重减少。因此，所获得的数据强调了这样一个事实，即在非洲爪蟾tRNA（Sec）中，这两个G是TATA启动子不可或缺的一部分。凝胶阻滞实验表明，GG到TT的替换导致人TBP在体外失去支持高效转录的能力，这与滞后复合物模式的改变相关。总之，本报告中呈现的数据支持一种模型，即TBP直接与tRNA（Sec）基因的TATA元件相互作用，这与经典的无TATA tRNA基因所提出的相互作用类型不同。
