Deciphering and engineering of the molecular diversity of NRPS-derived azacyclic alkaloids in bacteria

虽然细菌中的许多生物合成途径导致一种或有限数量的产物，但某些系统产生多种代谢物。细菌吡咯利西啶生物碱（PAs）的途径代表了这种现象的显著例子。常见的生物合成方案包括双模非核糖体肽合成酶（NRPS）和单加氧酶，与辅助酶和/或自发化学反应相结合，产生各种氮杂环，如吡罗里嗪类和环氨基甲酸酯类。在最近的工作中，已经发现这些化合物中的一些在与宿主相互作用时减弱了产生细菌的毒力。控制这种多样化的分子机制及其潜在的生物活性仍然未知。鉴于氮胞环分子的高度兴趣和广泛的药物潜力，本项目拟破译细菌中吡咯利西啶和相关生物碱的化学多样性的分子基础，阐明通路中关键酶的结构-功能关系，并应用所获得的知识来产生具有有趣生物活性的新天然衍生物，特别是作为人类主要病原体铜绿假单胞菌的抗毒化合物。

While many biosynthetic pathways in bacteria lead to one or a limited number of products, certain systems produce a diversity of metabolites. The pathways to the bacterial pyrrolizidine alkaloids (PAs) represent striking examples of this phenomenon. A common biosynthetic scheme involving a bimodular nonribosomal peptide synthetase (NRPS) and a monooxygenase, in combination with accessory enzymes and/or spontaneous chemical reactions, leads to diverse azacycles such as pyrrolizidines and cyclocarbamates. In recent work, several of these compounds have been found to attenuate virulence of the producing bacteria during interaction with its host. The molecular mechanisms governing such diversification and underlying their biological activity remain unknown. Given the high interest and broad pharmaceutical potential of azacycle-containing molecules, this project proposes to decipher the molecular basis for the chemical diversity of pyrrolizidine and related alkaloids in bacteria, to elucidate structure-function relationships for key enzymes in the pathways, and to apply the obtained knowledge to generate new-to-nature derivatives with interesting bioactivity, notably as anti-virulence compounds of a major human pathogen, Pseudomonas aeruginosa.