致病性大肠杆菌中新铁载体的发现与功能表征

Generally, siderophore biosynthesis is closely associated with the virulence of pathogens. Scientists only identified three siderophores in uropathogenic UTI89 strain which is one of key clinical strains causing urinary tract infection in women, they are yersiniabactin, salmochelin and enterobactin due to the undeveloped analytical capability in approximate 20 year ago. The biosynthesis and expression of yesiniabactin was observed to significantly contribute the virulent capacity of UTI89 during the infection. It is biosynthesized by a serial small-molecule metabolites encoded by 11 virulent gene, and the biosynthetic pathway was composed of numerous steps. Whereas it is confidently argued that the yerisinibactin dependent biosynthetic pathway is supposed to produce more novel siderophores, which should coordinately build the virulence of UTI89 at different perspectives. In this study, we aim at discovering and identifying novel siderophores hosted by the yersiniabactin dependent pathways using metabolomics-genetic combinational strategy, consequently construct the relevant biosynthetic pathways and annotate the virulence associated functions based on in vitro and in vivo models. Together, this study shall lead us to better understand the virulent foundation of UTI89, and verify novel targets for diagnosis and treatment of urinary traction infection for the first instance, and further facilitate the discovery and development of the lead compounds of novel antibiotics via structurally modifying the novel siderophores underlying the virulence of UTI89 causing urinary tract infection.

铁载体的生物合成与病原菌的致病力密切相关。鉴于20多年前受到研究水平的限制，科学家仅从诱发群体性尿路感染的致病性大肠杆菌UTI89菌株中发现yersiniabactin，salmochelin和enterobactin 等3种铁载体，其中yersiniabactin生物合成与表达显著贡献UTI89对宿主的致病力。Yersiniabactin由11个致病基因经多步反应定向编码而成，如此复杂的反应体系，有理由相信该合成通路会有更多铁载体类化合物的生成，从不同角度贡献UTI89对宿主的致病力。本课题将运用代谢组学与遗传学整合策略，以致病性大肠杆菌UTI89为模板，发现与鉴定yersinibactin 合成通路依赖型铁载体，并表征其功能， 以阐明UTI89的致病力物质基础，发现尿路感染潜在治疗靶点，同时以新的关键铁载体为基础，进行结构修饰改造来开发新型抗生素

铁载体的生物合成与病原菌的致病力密切相关。鉴于20多年前受到研究水平的限制，科学家仅从诱发群体性尿路感染的致病性大肠杆菌UTI89菌株中发现 yersiniabactin，salmochelin和enterobactin 等3种铁载体，其中yersiniabactin生物合成与表达显著贡献UTI89对宿主的致病力。Yersiniabactin由11个致病基因经多步反应定向编码而成，如此复杂的反应体系，有理由相信该合成通路会有更多铁载体类化合物的生成，从不同角度贡献UTI89对宿主的致病力。在本课题中，我们开发了精准修饰代谢组学方法，可以对超过200个小分子化合物进行精准鉴定。以致病性大肠杆菌UTI89为模板，发现并鉴定yersinibactin 合成通路依赖型铁载体-HPTzTn-COOH，并对该新型铁载体的功能进行了初步验证，证明了铁载体的生物合成过程参与了大肠杆菌的致病性，为新药物的研发以及铁载体的发现做出了巨大贡献。除此之外，在探究铁载体致病性的同时，我们发现生物膜的形成与大肠杆菌的致病力及耐药性都有这巨大的联系，然而生物膜的生成机制目前尚不清楚。因此本课题探究了铁离子与生物膜形成的关系，并利用精准靶向代谢组学，从代谢的角度寻找生物膜形成的原因。结果显示，铁对生物膜的生成具有抑制作用。最终通过寻找差异代谢物，我们认为五个代谢物：色氨酸，亚精胺，亮氨酸，5’-MTA, CMP，可以调控生物膜的形成。基于功能代谢组学策略，通过多组学整合，初步找到了不同代谢物影响生物膜形成的机制，为后续研发抗生物膜的药物提供了方向。继而铁的运输无疑是离不开铁载体，因此接下来我们将继续探究铁载体，生物膜形成以及大肠杆菌致病力三者之间的关系，从代谢的角度了解其中的机理，从而开发靶向药物应对细菌感染。