抗真菌药物UK-2A的组合生物合成研究

真菌病害对人类的生存和健康构成了严重的威胁，随着耐药菌株的频繁出现，新型抗真菌药物的需求也变得愈加迫切。UK-2A及其半合成衍生物fenpicoxamid是一类作用于新靶点的新型抗真菌药物，能有效杀灭耐药真菌。但是由于结构复杂，化学修饰产生的结构多样性有限，因此目前对其的构效关系研究还不深入，仍具有很大的研发空间。我们前期在对抗霉素的研究过程中，发现其生物合成途径具有很高的灵活性，能够通过底物的变化合成出大量的新结构类似物，而具有相似骨架的UK-2A的生物合成途径却具有较高的专一性。本项目中，我们将解析UK-2A中关键酶的底物识别机制，揭示其控制底物专一性的关键因素。在此基础上发展酶工程手段，拓展关键酶的底物选择性，并利用组合生物合成方法大幅度拓展UK-2A的结构多样性。在此基础上，发展高通量活性筛选体系，对UK-2A类似物进行全面的考察，以期获得更好的新型抗真菌药物。

Fungal infections are major threats to the community of human beings. With the increasing emergence of multidrug-resistant fungal pathogens, the demand for development of novel antifungal drugs have become more and more urgent. UK-2A and its semisynthetic derivative fenpicoxamid are a new class of antifungal agents. By imposing on the novel target, these agents are able to efficiently kill drug-resistant pathogenic fungi. Their structure activity relationship (SAR) analysis was based chemical modification. However the complexity of their molecular structures, renders these efforts very challenging and only limited structural varieties have been achieved so far. To develop more potent active agents, other effective approaches e.g. biosynthetic engineering for structural diversification are desired. In the previous study of antimycin biosynthesis, we found that its biosynthetic pathway is very flexible. By employing substrate varieties, large numbers of novel antimycin analogues can be generated through biosynthesis. Interestingly, UK-2A bears an identical scaffold, however its biosynthetic pathway is not as flexible as to antimycin's which forms a bottleneck for combinatorial biosynthesis. In this study, we will be focused on deciphering the mechanism behind substrate specificity and developing protein engineering approaches to broaden the substrate scopes of some key enzymes. With these basis, we will further develop combinatorial approach and high-throughput screening strategy to enormously generate structural varieties of UK-2A and rapidly access their bioactivities. By deeply excavating the potential of UK-2A scaffold, we believe it will be promising for this study to find some novel potent antifungal agents.