REGULATION OF GENE EXPRESSION IN BACTERIOPHAGE T4

这个项目涉及基因表达的两个方面：(I) 转录的选择性和(Ii)转录后处理 核糖核酸。这两种现象都涉及蛋白质与核的特定相互作用。 酸和调查的目的将是了解其机制 这种相互作用及其与生理控制事件的相关性。 噬菌体T4在大肠杆菌中的开发提供了一个有用的开放模型系统 遗传、生物化学和生理方法的结合。在……里面 在T4发育过程中，不同的基因组通过 病毒诱导的宿主转录机制的修改。先前 我们已经证明，T4诱导RNA聚合酶的ADP核糖化 在体外，α亚基可以关闭某些T4启动子。该机制和 这一现象的生物学作用将被研究。以前我们有过 在T4 tRNA基因区定位了几个转录终止位点。 RNA聚合酶与这些位点的相互作用将在 为了了解转录终止的精细机制。我们 还打算开发一种允许使用该终端的体外系统 T4诱导的抗流产(抗Rho)效应的分析站点： T4基因表达转换的可能机制 从即刻提前到延迟提前的功能。体外纯化原代细胞 T4DNA的转录本为搜索提供了方便的底物 RNA加工酶的研究。在之前的工作中，一种新的内切酶 对参与转移RNA成熟的部分进行了纯化。我们打算 为了进一步纯化和研究这种被认为是主要tRNA的酶 大肠杆菌核酸内切酶的加工。还建议继续我们的 核糖核酸酶III参与T4mRNA加工的研究。

This project is concerned with two aspects of gene expression: (i) selectivity of transcription and (ii) post-transcriptional processing of RNA. Both phenomena involve specific interaction of proteins with nucleic acids and the investigation will be aimed at understanding the mechanisms of this interaction and their relevance to physiological control events. Bacteriophage T4 development in E.coli provides a useful model system open to a combination of genetic, biochemical and physiological approaches. In T4 development, different groups of genes are turned on and off by means of virus-induced modification of the host transcription machinery. Previously we have shown that T4-induced ADP-ribosylation of RNA polymerase alfa-subunit turns off certain T4 promoters in vitro. The mechanism and biological role of this phenomenon will be studied. Previously we have mapped several transcription termination sites in the T4 tRNA gene region. The interaction of RNA polymerase with these sites will be analyzed in order to understand the fine mechanism of transcription termination. We also intend to develop an in vitro system allowing to use the termination sites for the analysis of T4-induced antitermination (anti-rho) effect: the presumed mechanism of switching the T4 gene expression from immediate-early to delayed-early functions. Purified primary in vitro transcripts of T4 DNA provide convenient substrates for the search and study of RNA processing enzymes. In the previous work, a new endonuclease involved in maturation of transfer RNA was partially purified. We intend to further purify and study this enzyme which is thought to be a major tRNA processing endonuclease of E. coli. It is also proposed to continue our studies of the involvement of Ribonuclease III in the processing of T4 mRNA.