Inhibition of Prokaryote-Specific Saccharide Biosynthesis in Microbial Pathogens

描述（由申请人提供）：修饰N-和o -连接糖蛋白的聚糖，构成许多革兰氏阴性病原体细胞表面景观的关键元素，整合各种原核特异性碳水化合物，包括二N-乙酰杆菌胺（diNAcBac）和假氨基酸（Pse）。越来越多的遗传和生物学证据表明，修饰过的糖，如diNAcBac和Pse，是原核糖结合库中的基本元素，具有这些糖特征的细胞表面糖蛋白作为毒力因子，介导病原体-宿主相互作用并导致微生物感染的严重程度。先前的研究强调了这样一个事实，即与真核生物相比，原核生物中单糖具有惊人的多样性，然而，对合成小分子抑制剂的需求仍未得到满足，这些小分子抑制剂可以作为选择性工具来剧烈干扰其生物合成，以了解修饰糖与细菌致病性之间的关系。该研究包括基于片段的抑制剂设计和结构导向的配体优化方法，以及在开发催化UDP-diNAcBac和CMP-Pse生物合成关键步骤的氨基糖乙酰转移酶抑制剂方面进行深入的体外和体内分析。DiNAcBac和Pse是特别普遍的微生物碳水化合物，它们在空肠假单胞菌、鲍曼假单胞菌和淋病奈索菌的N-和o -连接糖蛋白中具有特征。这些微生物病原体是本研究的目标，因为在蛋白质糖基化和毒力之间建立了联系。我们提出，急性抑制糖蛋白生物合成基本早期步骤的小分子抑制剂将允许糖蛋白生物合成的时间控制，这是不可用的

DESCRIPTION (provided by applicant): Glycans decorating N- and O-linked glycoproteins, which constitute critical elements of the cell-surface landscape of many Gram-negative pathogens, integrate a variety of prokaryote-specific carbohydrates including di-N-acetyl bacillosamine (diNAcBac) and pseudaminic acid (Pse). There is growing genetic and biological evidence that modified saccharides, such as diNAcBac and Pse, are essential elements in the prokaryotic glycoconjugate repertoire and that cell surface glycoproteins that feature these sugars, serve as virulence factors, which mediate pathogen-host interactions and contribute to the severity of microbial infections. Previous studies have highlighted the fact that there is a striking diversity of monosaccharides in prokaryotes, relative to eukaryotes, however, there is a major unmet need for synthetic small molecule inhibitors that can be used as selective tools to acutely perturb their biosynthesis to understand the associations between modified sugars and bacterial pathogenicity. The proposed research involves fragment-based inhibitor design and structure-guided ligand optimization approaches together with incisive in vitro and in vivo analyses in the development of inhibitors of amino sugar acetyl transferases that catalyze key steps in the biosynthesis of UDP-diNAcBac and CMP-Pse. DiNAcBac and Pse are particularly prevalent microbial carbohydrates, which feature in the N- and O-linked glycoproteins of C. jejuni, A. baumannii and N. gonorrhoeae. These microbial pathogens are the targets of this research due to the established connections between protein glycosylation and virulence. We propose that small molecule inhibitors that acutely inhibit essential early steps in glycoprotein biosynthesis will allow for temporal control of glycoprotein biosynthesis that is not feasible with genetic approaches alone. Such inhibitors will be valuable new chemical tools that can provide insight into the effects of acutely inhibiting glycoprotein biosynthesis on motility, adherence and invasion in the native pathogen and in a pathogen/host context. The availability of inhibitors with appropriate biological properties will also validate the essentiality of carbohydrate modifications on microbial virulence in microorganisms (C. jejuni and N. gonorrhoeae) where genetic phenotyping and animal studies have provided clear evidence of the connections between glycosylation and virulence. This research will form a foundation for the application of similar strategic approaches with other pathogens that threaten human health where bioanalytical and bioinformatics approaches have been employed to predict the existence of glycoproteins that include highly modified carbohydrate building blocks. Ultimately we will address the central hypothesis that the enzymes that catalyze formation of unusual microbe-specific carbohydrate building blocks represent an "Achilles' heel" that can be exploited in the development of agents that can attenuate the virulence of serious human pathogens, which can be exploited in the battle against infectious diseases.