Basis of gene regulation by a guanine-binding mRNA

描述(申请人提供)：最近的发现揭示了一大类位于细菌mRNAs 5‘非翻译区的序列基序，它们能够在转录或翻译水平上调节基因表达，以响应细胞内代谢物的浓度。这些被称为核糖开关的RNA元件能够通过结合小分子(例如鸟嘌呤、赖氨酸或焦磷酸硫胺素)直接影响基因调控。在枯草杆菌中，这些RNA元件似乎控制着至少2%的基因的适当表达，这表明它们是细胞内基本重要的调节机制。为了了解这些元件是如何控制基因表达的，我们已经获得了对X射线的衍射率至少达到2.9A的鸟嘌呤核糖开关配体复合体的晶体。利用X射线结晶学，这种结构以及相关的腺嘌呤反应元件将被确定，以定义RNA的特征，这些特征有助于配体结合的高亲和力和特异性，这将导致对代谢物如何影响基因调控的一般理解。同时，将使用等温量热法(ITC)和一系列含有官能团缺失的RNA来探索配体识别的能量学。

DESCRIPTION (provided by applicant): Recent discoveries have revealed a broad class of sequence motifs located in the 5' untranslated region of bacterial mRNAs that have the ability to regulate gene expression at the level of either transcription or translation in response to intracellular metabolite concentrations. These RNA elements, dubbed riboswitches, are able to directly effect gene regulation by binding a small molecule (guanine, lysine or thiamine pyrophosphate, for example). In B. subtilis, these RNA elements appear to control the proper expression of at least 2% of all genes, suggesting that they are a fundamentally important regulatory mechanism within the cell. To understand how these elements control gene expression crystals of a guanine riboswitch-ligand complex that diffract X-rays to at least 2.9 A resolution have been obtained. Using X-ray crystallography, this structure, along with the related adenine-responsive element will be determined to define the features of the RNA that contribute to the high affinity and specificity of ligand binding which will lead to a general understanding of how gene regulation can be effected by metabolites. In parallel, the energetics of ligand recognition will be probed using isothermal calorimetry (ITC) and a series of RNAs that contain functional group deletions.