Protein/Protein Interactions in Prokaryotic Gene Control

描述(申请人提供)：细菌中的转录是由从细菌到人类保守的多亚基RNA聚合酶(RNAP)进行的。启动子特异的转录启动依赖于RNAP的？亚基，它必须与催化熟练的核心酶结合才能形成全酶。历史上被定义为启动因素，？也可以与转录延伸复合体保持关联，并在延伸过程中影响转录过程。尤其是，？可以通过在基因的初始转录区域内与启动子样的DNA序列元件建立序列特异性的相互作用来诱导早期伸长暂停。这项拟议的研究建立在这样一个证据的基础上，即这种类似启动子的停顿诱导元件可以起到抑制？在伸长的最早阶段损失，增加？整个转录单位的伸长复合体的含量。生物信息学分析的结果表明，至少有20%的大肠杆菌启动子与启动子近端依赖的停顿元件有关，这意味着这种调节？延伸复合体的含量可能是大肠杆菌转录的一般特征。这项拟议研究的第一个目的是调查？对大肠杆菌基因表达的滞留。第二个目标是调查是否有潜在的作用？在转录过程中，伸长延伸到了初级以外吗？因素和决定是否不同类型的？因子可以参与同一转录单位的起始和延伸(？“交叉监管”)。第三个目的是研究启动子-近端停顿元件影响？下游延伸复合体的含量。第四个目标是研究可能对细胞存活至关重要的特定核心相互作用是否促进？在停顿的早期伸长复合体的背景下来自DNA。总之，拟议的实验将导致更深入地理解经典启动因子在转录延伸过程中的作用，有助于积累证据，证明启动后调控事件在原核生物和真核生物中的重要性。

DESCRIPTION (provided by applicant): Transcription in bacteria is carried out by a multi-subunit RNA polymerase (RNAP) that is conserved from bacteria to humans. Promoter-specific transcription initiation depends on the ??subunit of RNAP, which must associate with the catalytically proficient core enzyme to form the holoenzyme. Historically defined as an initiation factor, ? can also remain associated with the transcription elongation complex and influence the transcription process during elongation. In particular, ? can induce early elongation pausing by establishing sequence-specific interactions with promoter-like DNA sequence elements within the initial transcribed region of a gene. The proposed research builds on the demonstration that such promoter-like pause- inducing elements can function to inhibit ? loss during the earliest stage of elongation, increasing the ? content of elongation complexes throughout the transcription unit. The results of bioinformatic analyses suggest that promoter-proximal ?-dependent pause elements are associated with at least 20% of all E. coli promoters, which implies that this mechanism for regulating the ? content of elongation complexes is likely a general feature of transcription in E. coli. The first aim of the proposed research is to investigae the effects of ? retention on E. coli gene expression. The second aim is to investigate whether the potential roles for ? during transcription elongation extend beyond the primary ? factors and to determine whether different types of ? factors can participate in initiation and elongation on the same transcription unit (? "cross-regulation"). The third aim is to investigate the mechanism by which promoter-proximal pause elements influence the ? content of downstream elongation complexes. The fourth aim is to investigate whether a specific ?-core interaction that may be essential for cell viability facilitates the release of ? from the DNA in the context of a paused early elongation complex. Together, the proposed experiments will lead to a deeper understanding of the roles of a classical initiation factor during transcription elongation, contributing to an accumulating body of evidence for the importance of post-initiation regulatory events in both prokaryotes and eukaryotes.