STRUCTURE AND FUNCTION OF RNA-MODIFYING PROTEINS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。在RNA中引入碱基修饰已被确定为多种生物基因组中编码蛋白质多样化的重要机制。已经鉴定出许多脱氨酶可以催化tRNA、mRNA甚至病毒RNA中核碱基的直接变化。这些蛋白质是产生抗体多样性、对入侵病毒的先天细胞反应以及在翻译过程中引入tRNA退化以识别单个tRNA的多个密码子所必需的。目前的研究重点是研究腺苷脱氨酶修饰RNA中特定位点的化学机制。我们目前的研究重点是TadA，这是一种来自细菌的酶，可以在特定tRNA的反密码子位置的摆动位置引入肌苷。该方法是利用x射线晶体学生成这些酶与靶RNA结合的新结构。目前的实验旨在通过将蛋白质与代表反应途径不同步骤的RNA中间体结晶，使这种蛋白质如何识别并进行RNA的化学修饰可视化。这些结果将对RNA识别和其他密切相关的作用于DNA和RNA的脱氨酶的催化作用产生影响。

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. Introducing modifications to bases in RNA has been identified as an important mechanism for diversification of proteins encoded in the genomes of various organisms. Numerous deaminases have been identified that catalyze direct changes to nucleobases in tRNA, mRNA, and even viral RNA. Such proteins are required for generating antibody diversity, innate cellular responses to invading viruses, as well as introducing tRNA degeneracy for recognition of multiple codons with a single tRNA during translation. The focus of the current research is to study the chemical mechanism of adenosine deaminases that modify specific sites in RNA. We are focusing our current studies on TadA, an enzyme from bacteria that introduces inosines at the wobble position at the anticodon position of a specific tRNA. The approach is to generate novel structures of these enzymes bound to target RNA using X-ray crystallography. Present experiments are designed to allow the visualization of how this protein recognizes and carries out the chemical modification of RNA by crystallizing the protein with RNA intermediates representing distinct steps along the reaction pathway. These results will have implications for RNA recognition and catalysis by other closely related deaminases that act on DNA and RNA.