Chemoenzymatic synthesis of novel siderophore scaffolds

新型铁载体支架的化学酶法合成

• 批准号: 2883889
• 金额: --
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2883889
• 关键词: Chemoenzymatic; synthesis; novel; siderophore; scaffolds

Iron is an indispensable cofactor for all microbial life. The ability to coordinate and activate molecular oxygen, in addition to optimal redox properties for electron transport, places it central to numerous cellular processes. It is therefore vital that iron homeostasis is carefully managed. Although iron has a high natural abundance, it exists predominantly as Fe3+ in aerobic environments and tends to form insoluble ferric hydroxides rendering it inaccessible to microorganisms. Organisms have therefore evolved complex strategies for iron acquisition and storage. Whilst several mechanisms are known, a common approach employed by bacteria and fungi is the production of low-molecular-weight compounds known as siderophores, which serve as high-affinity iron chelators. In fungi, the majority of siderophore compounds produced belong to the hydroxamate class. This functionality originates from L-ornithine, which is N5-hydroxylated and subsequently N5-acylated to yield a bidentate ligand. Typically, siderophores possess three hydroxamate units, producing a hexadentate ligand, which promotes formation of a polyhedral Fe3+ complex with binding constants in the 1022 - 1032 range. Whilst the physiological function of hydroxamate siderophores in fungi is well established, the molecular details of their biosynthesis remain poorly characterised. Genes encoding for large non-ribosomal peptide synthetase (NRPS) enzymes are known to be responsible for the assembly of peptidyl siderophores. Recent work on the SidD NRPS, responsible for the biosynthesis of the siderophore fusarinine C, revealed a highly unusual nonlinear behaviour to construct the depsipeptide siderophore structure. These included observations of inter-module loading of amino acids and an iterative cycle of chain extension reactions.The biosynthetic gene cluster in Penicillium rubens responsible for fusarinine C, shares very similar domain architecture to that of coprogen. It also shares a similar substrate, anhydromevalonyl-hydroxyornithine, although coprogen is made from the trans isomer rather than the cis. Despite the similarity of domains and substrate, a very distinct product structure, coprogen, is formed. This PhD projects aim is to characterise the biosynthetic pathway responsible for coprogen production, elucidate the molecular details in the biosynthesis of the trans monomeric unit and the full depsipeptide, and to determine the 3D structure of the NRPS enzyme complex.

铁是所有微生物生命不可或缺的辅因子。除了电子传输的最佳氧化还原性质外，协调和激活分子氧的能力使其在许多细胞过程中处于中心地位。因此，认真管理铁的动态平衡是至关重要的。虽然铁具有很高的天然丰度，但在有氧环境中，它主要以Fe3+的形式存在，并倾向于形成不溶于水的氢氧化铁，使微生物无法接触到它。因此，生物体进化出了获取和储存铁的复杂策略。虽然已知有几种机制，但细菌和真菌使用的一种常见方法是产生被称为铁载体的低分子化合物，这些化合物充当高亲和力的铁络合剂。在真菌中，产生的大多数铁载体化合物属于异羟甲酸酯类。这一功能源于L-鸟氨酸，它被N5-羟基化，然后N5-酰化生成双齿配体。通常，铁载体具有三个异羟甲酸酯单元，产生一个六齿配体，促进形成结合常数在1022-1032范围内的多面体Fe3+络合物。虽然真菌中羟甲酸铁载体的生理功能已经得到很好的证实，但其生物合成的分子细节仍然缺乏特征。编码大的非核糖体多肽合成酶(NRPS)的基因是已知的负责组装多肽铁载体的基因。SIDD NRPS负责铁载体Fusarinine C的生物合成，最近的工作揭示了构建深肽铁载体结构的一种非常不寻常的非线性行为。这些包括氨基酸模块间负载的观察和扩链反应的迭代循环。鲁本青霉中负责褐变C的生物合成基因簇与辅原基因具有非常相似的结构域结构。它也有一个相似的底物，无氢甲伐隆-羟基鸟氨酸，尽管辅原是从反式异构体而不是顺式异构体产生的。尽管结构域和底物相似，但形成了一种非常不同的产品结构，即辅原。本博士项目的目的是描述负责辅原产生的生物合成途径，阐明反式单体单位和完整深肽生物合成中的分子细节，并确定NRPS酶复合体的三维结构。