STRUCTURE OF AN AMINO ACID-SENSING RIBOSWITCH

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目和 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 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称为核糖开关的 mRNA 元件与小细胞代谢物（如辅酶、糖、氨基酸和核碱基）的相互作用来控制。核糖开关通常由两个区域组成。第一个区域形成进化保守且独立折叠的代谢物结合域，对某种代谢物具有特异性。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，该表达平台通常通过翻译或转录减弱来调节基因表达。 我们的研究工作重点是确定核糖开关代谢物传感模块在自由和结合状态下的三维结构，以更好地理解表达平台利用的构象转变来进行基因表达的变构调节。这些研究将揭示决定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型抗菌药物靶点。 在几种核糖开关类别中，氨基酸特异性核糖开关尚未在结构上得到表征。尽管事实上许多氨基酸可以被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RNA结构不同的构象，因为核糖开关可以在许多其他天然氨基酸、它们的前体和肽背景中的氨基酸中区分单个氨基酸。氨基酸赖氨酸特异的核糖开关（长度为 174 nt）也不同于早期的核糖开关（长度约为 70 nt），因为它的尺寸更大，并且具有多茎连接次级折叠。

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.