STRUCTURE/FUNCTION OF POL III TRANSCRIPTION FACTORS

RNA聚合酶III（pol III）的转录是转录的基础。 在所有真核生物中的重要性，因为它的产物参与各种 包括蛋白质合成，RNA 加工和蛋白质运输。 这项工作的长期目标是 为了获得对限制步骤的详细的生物化学理解， pol III基因转录。 为此，我们正在研究增加 转录与“激活”显性和隐性 酿酒酵母的PCF 1基因突变。 PCF 1编码 TFIIIC中含有三肽重复序列（TPR）亚基 （TFIIIC 131），并负责募集异源三聚体 起始因子TFIIIB与转录起始点上游的DNA结合 绝佳的价钱 TFIIIB的募集通过直接蛋白-蛋白 TFIIIC 131和TFIIIB相关因子TFIIIB 70之间的相互作用。 显性和隐性PCF 1突变被认为有助于 在TFIIIB组装中的不同部分限制步骤， 影响TFIIIC 131中不同的蛋白质构象变化，和/或 TFIIIIB70. 使用纯化的酵母因子和 提出了重组蛋白和分子遗传学策略， (i)确定受影响的步骤和“激活”机制， 显性和隐性PCF 1突变，（ii）定义相互作用 TFIIIC 131和IFIIIB 70之间的结构域和（iii）评估TPR的作用 结构/功能关系，包括“长程”TPR-TPR TFIIIB复合物组装中的相互作用。 这些研究的结果 将提供一个基础，了解如何转录控制的 pol III基因表达可以在细胞周期中或在细胞周期中实现。 对细胞生长速率或其他化学、生物或 环境因素 此外，调查结果将建立 考虑不同TPR的功能和调节的模式 蛋白质家族

Transcription by RNA polymerase III (pol III) is of fundamental importance in all eukaryotes since its products participate in a variety of essential cellular processes including protein synthesis, RNA processing and protein transport. The long-term goal of this work is to obtain a detailed biochemical understanding of the limiting steps in pol III gene transcription. To this end, we are studying the increased transcription associated with "activating" dominant and recessive mutations in the PCF1 gene of Saccharomyces cerevisiae. PCF1 encodes the tetratricopeptide repeat (TPR)-containing subunit of TFIIIC (TFIIIC131) and is responsible for recruiting the heterotrimeric initiation factor TFIIIB to the DNA upstream of the transcription start site. The recruitment of TFIIIB is achieved by direct protein-protein interactions between TFIIIC131 and the TFIIB-related factor, TFIIIB70. The dominant and the recessive PCF1 mutations are thought to facilitate different partially limiting steps in the assembly of TFIIIB by affecting distinct protein conformational changes in TFIIIC131 and/or TFIIIB70. Biochemical experiments using purified yeast factors and recombinant proteins and molecular genetic strategies are proposed to (i) identify the steps affected and the mechanisms of "activation" by the dominant and recessive PCF1 mutations, (ii) define the interaction domains between TFIIIC131 and IFIIIB70 and (iii) assess the role of TPR structure/function relationships including "long range" TPR-TPR interactions in TFIIIB complex assembly. The results of these studies will provide a basis for understanding how transcriptional control of pol III gene expression may be achieved during the cell cycle or in response to cell growth rate or other chemical, biological or environmental factors. In addition, the findings will establish aparadigm for considering the function and regulation of the diverse TPR family of proteins.