Bongards Christine, Chew Boon Shang, Lehming Norbert
Department of Microbiology, Faculty of Medicine, National University of Singapore, Block MD4, 5 Science Drive 2, Singapore 117597.
Biochem J. 2003 Feb 15;370(Pt 1):141-7. doi: 10.1042/BJ20021548.
According to the recruitment model, transcriptional activators work by increasing the local concentration of one or several limiting factors for the transcription process at the target promoter. The TATA-binding protein Tbp1 has been considered as a likely candidate for such a limiting factor. We have used a series of Gal4p and Tbp1 mutants to correlate the in vivo interaction between the two proteins with the strength of activation. We find a clear correlation between activation strength and in vivo interaction for the series of Gal4p mutants. Consistently, the weaker activator Gcn4p does not interact with Tbp1. However, a corresponding analysis of the series of Tbp1 mutants revealed that Tbp1 is not an essential target of the acidic activators Gal4p and Gcn4p. Furthermore, detailed analysis of a Tbp1 mutant deficient for transcriptional activation by Gal4p revealed that the mutant is defective in interactions with five other proteins involved in the process of transcription.
根据招募模型，转录激活因子通过增加目标启动子转录过程中一种或几种限制因子的局部浓度来发挥作用。TATA结合蛋白Tbp1被认为是这种限制因子的一个可能候选者。我们使用了一系列Gal4p和Tbp1突变体，将这两种蛋白在体内的相互作用与激活强度关联起来。我们发现，对于一系列Gal4p突变体，激活强度与体内相互作用之间存在明显的相关性。同样地，较弱的激活因子Gcn4p不与Tbp1相互作用。然而，对一系列Tbp1突变体的相应分析表明，Tbp1不是酸性激活因子Gal4p和Gcn4p的必需靶点。此外，对一个缺乏Gal4p介导的转录激活能力的Tbp1突变体的详细分析表明，该突变体在与转录过程中涉及的其他五种蛋白的相互作用方面存在缺陷。
