Biosynthesis of hypermodified guanosines

超修饰鸟苷的生物合成

• 批准号: 7102895
• 负责人: Valerie A de Crecy-Lagard
• 金额: $ 27.45万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-02 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7102895
• 关键词: Bacillus subtilis; Escherichia coli; Staphylococcus aureus; amine oxidoreductase; chemical structure function; enzyme activity; enzyme structure; folate; genetic library; guanosine; guanosinetriphosphatases; microorganism metabolism; nucleic acid biosynthesis; nucleoside analog; posttranscriptional RNA processing; pteridines; purine /pyrimidine metabolism; transfer RNA

DESCRIPTION (provided by applicant): Project Summary. The post-transcriptional processing of transfer RNA (tRNA) involves a number of functionally distinct events essential for tRNA maturation. The phenomenon of nucleoside modification is perhaps the most remarkable of these events, and results in a wealth of structural changes to the canonical nucleosides. Two of the most remarkable modified nucleosides found in tRNA are the 7-deazaguanosine derivatives queuosine and archaeosine, which have putative roles in translation and RNA stabilization, respectively. While evolutionarily related, these nucleosides are segregated within separate Domains; queuosine is ubiquitous among Bacteria and Eukarya, while archaeosine is only present in the Archaea. The 7-deazapurine structure in general is widespread in biology, where it is found in a variety of natural products such as the antitumor antibiotics toyocamycin, sangivamycin, and tubercidin from Streptomyces. The biosynthetic pathways to these deazapurines are poorly understood, a fact that has stymied functional studies. The availability of hundreds of sequenced genomes now allows the identification of genes and pathways using a comparative genomics approach. This approach was used to discover five new enzymes in the de novo biosynthesis of queuosine and archaeosine, and potentially of other 7-deazapurine metabolites. Notably, this pathway is limited to prokaryotes, and some of these newly discovered enzymes appear to catalyze chemistry unprecedented in biology. The long-term objectives of this project are to elucidate the biosynthesis and metabolism of 7-deazapurines in prokaryotes. The specific aims of this proposal are 1) to elucidate the role of these new enzymes in the early steps in the queuosine and archaeosine biosynthetic pathways leading to the formation of the common precursor 7-cyano-7-deazaguanine, 2) to initiate studies into the broader metabolism of these modified nucleosides, and 3) to investigate the mechanism and structure of one of these enzymes, a novel nitrile oxidoreductase. This proposal brings an ensemble of bioinformatic, genetic, biochemical, and chemical approaches to the problem of elucidating the biosynthesis of 7-deazaguanine modified nucleosides. The study of this new pathway and the constituent enzymes will provide unprecedented access to elucidating the biology of 7-deazapurine metabolism and its manipulation. Relevance. The pathway to 7-deazapurines is unique to microorganisms, and many of the constitute enzymes are potentially new antibacterial targets. Furthermore, one of the enzymes is a novel nitrile oxidoreductase that may have applications in industrial biocatalysis.

描述(申请人提供)：项目摘要。转移RNA(TRNA)的转录后加工涉及许多对tRNA成熟至关重要的功能上不同的事件。核苷修饰的现象可能是这些事件中最引人注目的，它导致了典型核苷的大量结构变化。在tRNA中发现的两种最显著的修饰核苷是7-去氮鸟苷衍生物Queuosine和Archosine，它们分别在翻译和RNA稳定中发挥作用。虽然这些核苷在进化上是相关的，但它们被分离在不同的结构域中；队列蛋白在细菌和真核生物中普遍存在，而考古蛋白只存在于古生物中。7-去氮嘌呤结构在生物学中普遍存在，它存在于各种天然产物中，如抗肿瘤抗生素托伊卡霉素、桑吉霉素和来自链霉菌的结节杀菌素。人们对这些去氮嘌呤的生物合成途径知之甚少，这一事实阻碍了功能研究。数百个测序的基因组现在可以使用比较基因组学方法来识别基因和途径。这一方法被用来发现在奎宁和考古糖的从头生物合成中的五种新的酶，以及潜在的其他7-去氮嘌呤代谢物。值得注意的是，这一途径仅限于原核生物，其中一些新发现的酶似乎能够催化生物学中前所未有的化学作用。该项目的长期目标是阐明7-地氮嘌呤在原核生物中的生物合成和代谢。这项建议的具体目的是1)阐明这些新的酶在导致共同前体7-氰基-7-去氮鸟嘌呤形成的队列苷和考古辛生物合成途径的早期步骤中的作用，2)启动对这些修饰的核苷更广泛的代谢的研究，以及3)研究这些酶之一的机制和结构，一种新的丁腈氧化还原酶。这一建议为阐明7-去氮鸟嘌呤修饰核苷的生物合成问题提供了一系列生物信息学、遗传学、生化和化学方法。对这一新途径及其组成酶的研究将为阐明7-去氮嘌呤代谢的生物学及其调控提供前所未有的途径。关联性。7-去氮尿嘧啶的合成途径是微生物所特有的，许多构成酶可能是新的抗菌靶点。此外，其中一种酶是一种新型的丁腈氧化还原酶，可能在工业生物催化中有应用。