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

曲霉菌病是由曲霉菌属真菌引起的一系列疾病，是肺部疾病和死亡的主要原因，在患有肺部疾病（例如肺结核，哮喘，囊性纤维化和慢性阻塞性肺病）的个体中，以及由于器官移植或化疗而导致免疫功能低下的个体中。即使采用现有抗真菌药物进行积极治疗，侵袭性曲霉病的死亡率仍超过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。在这里，重点是UapA，高亲和力尿酸/黄嘌呤质子同向转运体从丝状真菌构巢曲霉，并分享高亲和力，高容量的嘌呤同向转运体AfUapC从相关的病原真菌，烟曲霉的高度序列同源性。别嘌呤醇是一种现有的黄嘌呤氧化酶抑制剂，已获批用于治疗高尿酸血症。最近，别嘌呤醇已被证明对利什曼原虫感染有效，但它尚未被探索作为新的抗真菌药的模板。已知别嘌呤醇是UapA的非天然底物，但对其转运机制和对真菌生长的影响知之甚少。已证明获得UapA +别嘌呤醇的结构具有挑战性，然而我们具有与天然底物黄嘌呤复合的UapA结构。因此，最初的努力集中在基于结构的药物设计使用别嘌呤醇和黄嘌呤作为模板。本研究的目的是：设计别嘌呤醇和黄嘌呤的衍生物，开发这些新化合物的合成方案，建立筛选这些新化合物的方法，包括a）与UapA的结合，B）对体外真菌生长的抑制作用，表征这些化合物通过UapA的转运动力学。

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.