Structure based drug design of novel anti-fungal agents imported into cells by the integral membrane transporter, UapA

曲霉病是由曲霉真菌引起的疾病的集合，是有肺部疾病(如肺结核、哮喘、囊性纤维化和慢性阻塞性肺疾病)的个人以及因器官移植或化疗而免疫受损的人肺部疾病和死亡的主要原因。即使用现有的抗真菌药物进行积极治疗，侵袭性曲霉病的病死率也超过50%。因此，开发能够消除这些感染的新型抗真菌药物势在必行。这项研究的重点是开发通过整合膜转运蛋白进入真菌细胞的新型药物。UapA是丝状真菌nidulans的一种高亲和力尿酸/黄嘌呤质子转运体，与相关病原真菌烟曲霉的高亲和力、高容量的嘌呤转运体AfUapC具有很高的序列同源性。别嘌醇是一种现有的黄嘌呤氧化酶抑制剂，已被批准用于治疗高尿酸血症。最近，别嘌醇已被证明对利什曼原虫感染有效，然而，它尚未被探索作为新型抗真菌药物的模板。别嘌醇是UapA的非天然底物，但对其转运机制和对真菌生长的影响却知之甚少。UapA+别嘌醇的结构已经被证明是具有挑战性的，然而我们在天然底物黄嘌呤中有UapA的复合体结构。因此，最初的努力集中在使用别嘌醇和黄嘌呤作为模板的基于结构的药物设计上。学生的目标是：设计别嘌醇和黄嘌呤的衍生物为这些新化合物的生产开发合成方案建立筛选这些新化合物的方法，从a)与UapA结合，b)在体外对真菌生长的抑制作用表征这些化合物通过UapA的传输动力学。

Aspergillosis, a collection of conditions caused by the Aspergillus fungus, is a major cause of lung disease and death in individuals with prior lung conditions (e.g. tuberculosis, asthma, cystic fibrosis and chronic obstructive pulmonary disease), and in those who are immunocompromised, as a result of organ transplantation or chemotherapy. Even following aggressive treatment with existing antifungals, fatality rates exceed 50% for invasive Aspergillosis. Consequentially, the development of novel antifungals capable of eliminating these infections is imperative. This research is focusing on developing novel drugs that are taken up into fungal cells via integral membrane transporters. Here the focus is on UapA, a high-affinity uric acid/xanthine proton symporter from the filamentous fungus Aspergillus nidulans, and shares high sequence homology with the high-affinity, high-capacity purine symporter AfUapC from the related pathogenic fungus, Aspergillus fumigatus. Allopurinol is an existing xanthine oxidase inhibitor and approved treatment for hyperuricemia. More recently, allopurinol has been shown to be effective against Leishmania infections, however it has not yet been explored as a template for novel antifungals. It is known that allopurinol is a non-native substrate of UapA, but little is understood about its translocation mechanism and effect on fungal growth. The structure of UapA + allopurinol has proved challenging to obtain however we have a structure of UapA in complex with the native substrate xanthine. Thus, initial efforts have focused on structure-based drug design using both allopurinol and xanthine as templates. The objectives of the studentship are to: Design derivatives of allopurinol and xanthineDevelop synthesis protocols for the production of these novel compoundsEstablish methods for the screening of these novel compounds in terms of a) engagement with UapA, b) inhibitory effects on fungal growth in vitroCharacterise the transport kinetics of these compounds through UapA.