STRUCTURE OF AN AMINO ACID-SENSING RIBOSWITCH

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 最近的研究表明，原核生物和真核生物中的基因表达都可以通过被称为核糖开关的mRNA元件与辅酶、糖、氨基酸和碱基等细胞小代谢物的相互作用来调控。核糖开关通常由两个区域组成。第一个区域形成进化保守的独立折叠的代谢物结合域，专用于特定的代谢物。第二个区域是非保守表达平台，携带基因表达信号。与代谢物结合相关的构象转变是通过表达平台来解释的，表达平台通常通过翻译或转录衰减来调节基因表达。 我们的研究工作集中在确定自由和结合状态下核糖开关代谢物传感模块的三维结构，以便更好地理解表达平台利用表达平台对基因表达进行变构调控的构象转变。这些研究将揭示核糖开关功能的分子机制，并将有助于评估核糖开关作为新的抗菌药物靶点。 在几类核糖开关中，氨基酸特异的核糖开关尚未被结构表征。尽管许多氨基酸可以被RNA-蛋白质界面上的RNA特异性识别，但这些核糖开关应该适应与蛋白质结合的RNA结构不同的构象，因为核糖开关可以区分许多其他天然氨基酸、其前体和多肽环境中的氨基酸。氨基酸赖氨酸(174-nT)特异的核糖开关也不同于早期的核糖开关(APP。长度为70-nT)，因为它的尺寸要大得多，而且有多茎连接的次级折叠。

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. Recent studies have shown that gene expression in both prokaryotes and eukaryotes can be controlled through interactions of mRNA elements, called riboswitches, with small cellular metabolites, such as coenzymes, sugars, amino acids and nucleobases. Riboswitches are typically composed of two regions. The first region forms evolutionary conserved and independently folded metabolite-binding domain, specific for a certain metabolite. The second region, non-conserved expression platform, carries gene expression signals. The conformational transitions associated with metabolite binding are interpreted through the expression platforms which regulate gene expression by typically translational or transcriptional attenuation. Our research efforts are focused on the determination of the three-dimensional structures of the riboswitch metabolite-sensing modules in the free and bound states, towards an improved understanding of the conformational transitions harnessed by the expression platforms for allosteric modulation of gene expression. These studies will uncover the molecular mechanisms dictating riboswitch function and will help in the evaluation of riboswitches as novel antimicrobial drug targets. Among several riboswitch classes, amino acid specific riboswitches have not been structurally characterized. Despite the fact that many amino acids can be specifically recognized by RNA on the RNA-protein interfaces, these riboswitches should adapt conformations different from the protein-binding RNA structures, because riboswitches can distinguish a single amino acid among many other natural amino acids, their precursors, and amino acids in the peptide context. The riboswitch specific to amino acid lysine (174-nt in length) is also distinct from earlier riboswitches (app. 70-nt in length), given its much larger size and multi-stem junctional secondary fold.