Regulation of Transcription Attenuation in the B. subtilis trp Operon

枯草芽孢杆菌Trp操纵子中的转录衰减受反式作用的RNA结合蛋白调节，该蛋白是MTR基因座的产物。在色氨酸存在的情况下，MTR识别并推测与Trp领导人转录本中的一个位点相结合。这种结合影响衰减器形成转录终止子。MTR基因包含两个结构基因，MTRA和MTRB；两者都是调节色氨酸操纵子所必需的。这项工作的目的是确定MTR如何识别其RNA靶标，以及它如何影响衰减器导致转录终止。具体目标是：1)纯化MTR并确定其亚单位结构。2)建立MTR功能的体外检测方法，包括RNA结合和转录调控。3)鉴定Trp先导转录本中的RNA靶点，并证明MTR结合了这个位点。还将研究RNA结合所需的MTR的特征。4)确定MTR的色氨酸激活机制。5)确定MTR是否调控其他基因。RNA结合蛋白作为基因调节器的重要性是显而易见的。特定序列的RNA-蛋白质相互作用调节着广泛的细胞过程。这项工作将提供有关蛋白质如何识别RNA以及RNA结合蛋白如何调控基因表达的信息。

Transcription attenuation in the Bacillus subtilis trp operon is regulated by a trans-acting RNA binding protein, the product of the mtr locus. In the presence of tryptophan, Mtr recognizes, and presumably binds to, a site in the trp leader transcript. This binding influences the attenuator to form a transcription terminator. The mtr locus contains two structural genes, mtrA and mtrB; both are required to regulate the trp operon. The objective of this work is to determine how Mtr recognized its RNA target and how it influences the attenuator to cause transcription termination. Specific objectives are to: 1) purify Mtr and determine its subunit structure. 2) develop in vitro assays for Mtr function including RNA binding and transcription regulation. 3) characterize the RNA target site in the trp leader transcript and demonstrate that Mtr binds this site. Features of Mtr required for RNA-binding will also be studied. 4) determine the mechanism of tryptophan activation of Mtr. 5) determine if Mtr regulates other genes. The importance of RNA-binding proteins as gene regulators is clear. Sequence- specific RNA-protein interactions regulate a wide range of cellular processes. This work will provide information about how proteins recognize RNA and how RNA-binding proteins regulate gene expression.