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（由申请人提供）：项目摘要。转运RNA（transfer RNA，tRNA）的转录后加工过程涉及许多对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显著的，并且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-脱氮鸟苷衍生物鸟苷和古苷，它们分别在翻译和RNA稳定中起假定的作用。虽然在进化上相关，但这些核苷被分离在不同的结构域中;古核苷在细菌和真核生物中普遍存在，而古核苷仅存在于真核生物中。7-脱氮嘌呤结构通常在生物学中广泛存在，其中它存在于多种天然产物中，例如来自链霉菌的抗肿瘤抗生素丰卡霉素、桑吉瓦霉素和杀结核菌素。这些脱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。数百个测序基因组的可用性现在允许使用比较基因组学方法鉴定基因和途径。这种方法被用来发现五个新的酶在从头生物合成的古梭苷和古梭苷，并可能的其他7-脱氮嘌呤代谢物。值得注意的是，这种途径仅限于原核生物，其中一些新发现的酶似乎催化了生物学中前所未有的化学反应。本项目的长期目标是阐明原核生物中7-脱氮嘌呤的生物合成和代谢。该提案的具体目的是1）阐明这些新酶在导致形成共同前体7-氰基-7-脱氮鸟嘌呤的古核苷和古核苷生物合成途径的早期步骤中的作用，2）启动对这些修饰核苷的更广泛代谢的研究，以及3）研究这些酶之一，一种新型腈氧化还原酶的机制和结构。该建议将生物信息学、遗传学、生物化学和化学方法的集合引入到阐明7-脱氮鸟嘌呤修饰核苷的生物合成的问题中。对这一新途径和组成酶的研究将为阐明7-去氮嘌呤代谢及其操纵的生物学提供前所未有的途径。本案无关7-脱氮嘌呤的合成途径是微生物所特有的，许多组成酶是潜在的新的抗菌靶标。此外，其中一种酶是一种新的腈氧化还原酶，可能在工业生物催化中有应用。