RNA-BASED MECHANISMS OF TRANSCRIPTION ELONGATION CONTROL

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。该提案的目标是通过建立一个在联邦资助的RO1水平上具有竞争力的研究项目来建立肯塔基州的研究能力。该项目旨在了解转录延伸控制及其进化机制。我们提出表征一个独特的机制，转录延伸控制最初发现在噬菌体HK022。HK022是感染大肠杆菌的λ家族的温带噬菌体。大多数λ噬菌体家族成员使用噬菌体编码蛋白通过抑制转录终止来促进基因表达。HK022不需要抗终止蛋白，而是依赖于新生RNA转录物中的位点与宿主RNA聚合酶的直接相互作用。这些位点被称为put，位于两个早期操纵子中的每一个，由未配对的碱基分开的两个茎和环组成。网站的结构对它们的功能很重要。破坏碱基配对的突变减少了反终止，而重新建立碱基配对的二次突变则恢复了终止符。阻止抗终止的宿主突变体只发生在位于RNA聚合酶β初级亚基氨基末端的高度保守的锌指结构域。这些和其他结果表明，锌指区识别放RNA，并且该结构域在转录终止中具有普遍作用。通过比较野生型大肠杆菌与锌指基因突变细胞的基因表达谱，我们希望能确定这一高度保守结构域的细胞靶点。为了增加我们对RNA介导的抗终止和特定RNA结构元件的重要性的理解，我们将识别和表征抗终止RNA的其他例子。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this proposal is to build research capacity in the state of Kentucky by establishing a research program that is competitive at the RO1 level of federal funding. The project is designed to understand mechanisms of transcription elongation control and their evolution. We propose to characterize a unique mechanism of transcription elongation control originally discovered in the bacteriophage HK022. HK022 is a temperate phage of the lambda family that infects Escherichia coli. Most members of the lambda phage family use phage encoded proteins to promote gene expression by suppressing transcription termination. HK022 has dispensed with the requirement of an antitermination protein but relies on the direct interaction of sites in the nascent RNA transcript with the host RNA polymerase. These sites, called put, are located in each of the two early operons and are comprised of two stem and loops separated by an unpaired base. The structure of the sites i s important for their function. Mutations that disrupt base pairing reduce antitermination and secondary mutations that reestablish base pairing restore terminator read through. Host mutants that prevent antitermination occur exclusively in a highly conserved zinc-finger domain located at the amino terminus of the beta prime subunit of RNA polymerase. These and other results suggest that the beta prime zinc finger recognizes put RNA and that this domain has a general role in transcription termination. By comparing the gene expression profiles of wild type E. coli with cells that carry mutations in the zinc finger, we hope to identify cellular targets of this highly conserved domain. To increase our understanding of RNA-mediated antitermination and the importance of specific RNA structural elements, we will identify and characterize additional examples of antiterminator RNAs.