Aminoacyl-tRNA synthetases in archaea

描述（由申请人提供）： 氨酰-tRNA合成酶通过将特定的氨基酸连接到带有三联体反密码子序列的tRNA上来建立遗传密码。这些酶在系统发育树中的普遍分布表明，它们是对氨基酸和tRNA具有非凡特异性的最古老的蛋白质之一。然而，虽然对细菌和真核生物结构域的合成酶的广泛研究已经导致了底物特异性的一般原则，但这些不足以理解古细菌结构域的合成酶，古细菌结构域由在极端环境中茁壮成长的生物体组成。例如，最近的研究已经鉴定了古细菌詹氏甲烷球菌的双重特异性脯氨酰-tRNA合成酶（ProRS），其具有激活脯氨酸和半胱氨酸两者并催化tRNA与脯氨酸和半胱氨酸的氨酰化的能力。双特异性挑战了一种合成酶对应一种氨基酸的传统观点，并提出了许多关于合成酶特异性的基本问题。此外，双特异性ProRS的发现表明它与多合成酶复合物相关，该复合物构建合成酶-合成酶相互作用的网络以增强一般tRNA的结合。这提出了一个以前未被承认的进化关系与多合成酶复合体的桉树的可能性。此外，最近的研究表明，双特异性ProRS对tRNA氨酰化的特异性需要修饰，这与细菌和真核生物结构域的ProRS有很大不同。为了理解tRNA对双特异性ProRS的识别，鉴定必要的修饰是必要的。 本项目的目的一是阐明M.詹纳斯氏菌目的2是测试双特异性ProRS在多合成酶复合物的组织中的联网能力。目的3是鉴定双特异性ProRS所需的修饰以实现tRNA识别的特异性。这些目标将与M. jannaschii获得了更广泛的了解其氨酰-tRNA合成酶作为理解当代mRNA编码的蛋白质合成在现存生物体中的起源和进化的基础。

DESCRIPTION (provided by applicant): Aminoacyl-tRNA synthetases establish the genetic code by linking specific amino acids to tRNAs that bear triplet anticodon sequences. The universal distribution of these enzymes across the phylogenetic tree suggests that they are among the oldest proteins to have developed extraordinary specificity towards amino acids and tRNAs. However, while extensive studies of synthetases of bacterial and eucaryotic domains have led to general principles of substrate specificity, these are not sufficient to understand synthetases of the archaea domain, which consists of organisms that thrive in extreme environments. For example, recent studies have identified a dual specific prolyl-tRNA synthetase (ProRS) of the archaeon Methanococcus jannaschii, which has the ability to activate both proline and cysteine and catalyze aminoacylation of tRNA with proline and cysteine. The dual specificity has challenged the traditional view of one synthetase for one amino acid and raised many fundamental questions about synthetase specificity. In addition, the discovery of the dual-specific ProRS suggests that it is associated with a multi-synthetase complex that builds a network of synthetase-synthetase interactions to enhance binding of general tRNA. This raises the possibility of a previously un-recognized evolutionary relationship with the multi-synthetase complex of eucarya. Further, recent studies show that the specificity of tRNA aminoacylation by the dual-specific ProRS requires modification, which is a major departure from ProRS of bacterial and eucarya domains. To understand tRNA recognition of the dual-specific ProRS, the identification of the necessary modifications is necessary. Aim 1 of this project is to elucidate the molecular and structural basis of the dual-specificity of M. jannaschii ProRS. Aim 2 is to test the networking ability of the dual-specific ProRS in the organization of a multi-synthetase complex. Aim 3 is to identify the modification required for the dual-specific ProRS to achieve specificity of tRNA recognition. These aims are to be integrated with the functional genomics of M. jannaschii to gain a broader insight into its aminoacyl-tRNA synthetases as a basis for understanding the origin and evolution of contemporary mRNA-encoded protein synthesis in extant organisms.