Re-engineering of fungal sulphur metabolism to limit mould viability and virulence.

在世界范围内，烟曲霉是人类肺部最突出的真菌病原体。在欧洲，曲霉相关肺部疾病的全因负担每年超过200万例，其中包括多达5万例可能致命的侵袭性曲霉病。这种疾病的死亡率非常高，目前使用的抗真菌药物疗效不佳，并导致抗真菌耐药性。为了开发更成功的治疗方法，有必要更好地了解烟曲霉为何能够在哺乳动物组织中生长。这个过程的关键是代谢的多样性和从宿主获得营养的能力。我之前已经表明，硫(S)同化的调节对毒力至关重要，但是肺组织中硫的确切来源和体内真菌硫相关的代谢状态仍然未知。因此，在这个项目中，我的目的是澄清这两个重要的问题，这可能源于确定合适的靶点，以开发新的抗真菌疗法。首先，我将利用最先进的基因表达分析技术来研究感染过程中与硫相关的代谢状态。这种方法具有识别新的致病过程的潜力，这将有助于开发新的抗真菌策略。根据我的初步数据，我将集中研究两种被强烈认为与毒力相关的特定含s分子：蛋氨酸和硫化物（H2S）。蛋氨酸是一种氨基酸，它的生物合成似乎是烟曲霉必需的，与密切相关的真菌物种相反，但与其他致病真菌物种一致。我将确定生物合成途径的哪个方面是必不可少的，以及该活动与真菌生存的功能相关性。此外，我将在体外寻找特异性抑制真菌钴胺非依赖性蛋氨酸合酶活性的化合物，并在动物疾病模型中测试其作为抗曲霉药物的适用性。我也会问烟曲霉在感染过程中是否利用H2S作为硫源。硫化物是人体组织（包括肺）中产生的一种气体，作为信号分子。据描述，H2S修饰细胞内的蛋白质，以调节其活性。在细菌和哺乳动物细胞中已经观察到这种被称为硫水合作用的蛋白质改变，证明了它在整个进化过程中的保守性，因此，突出了它的重要性。真菌种类的磺化作用尚不清楚，因此我将研究这种蛋白质改变是否发生在烟曲霉中，以及它对真菌在肺部生长是否重要。我将使用收集到的结果来寻找真菌和/或哺乳动物硫代谢与曲霉病风险之间的相关性。这将通过对曼彻斯特大学（University of Manchester）整理的人类和真菌基因组数据的分析来实现。重要的是，这些分析可能强调相关的流行病学信息，这可能有助于患者管理。

On a world-wide basis, A. fumigatus is the most prominent fungal pathogen of the human lung. In Europe, the all-cause burden of Aspergillus-related lung disease exceeds 2 million cases per annum, including up to 50,000 potentially fatal cases of invasive aspergillosis. The mortality rate associated with this disease is very high, and antifungal drugs currently in use have suboptimal efficacy and result in antifungal resistance. In order to develop more successful therapies, it is necessary to better understand why A. fumigatus is able to grow in mammalian tissues. Critical to this process is metabolic versatility and the capacity to obtain nutrients from the host.I have previously shown that regulation of sulphur (S) assimilation is essential for virulence, however the exact S-source exploited in lung tissue and the in vivo fungal sulphur-related metabolic status remain unknown. Therefore, in this project I aim to clarify these two important issues, which may derive in the identification of suitable targets for the development of novel antifungal therapy.First, I will utilize state-of-the-art gene expression analysis technology to investigate the sulphur-related metabolic status during infection. This approach has the potential to identify novel pathogenic processes which will aid the development of novel antifungal strategy. Based on my preliminary data, I will concentrate on two specific S-containing molecules which are strongly suggested to be relevant for virulence: methionine and sulphide (H2S).Methionine is an amino acid whose biosynthesis appears to be essential for A. fumigatus, in contrast to closely related fungal species but in line with other pathogenic fungal species. I will determine what aspect of the biosynthetic pathway is essential, as well as the functional relevance of this activity for fungal survival.In addition, I will look for compounds that specifically inhibit the activity of the fungal cobalamin-independent methionine synthase in vitro, and test their suitability as anti-aspergillosis drugs in animal models of disease. I will also ask whether A. fumigatus exploits H2S as sulphur source during infection. Sulphide is a gas produced in the human tissues, including the lungs, as signalling molecule. It has been described that H2S modifies proteins inside the cells, to regulate their activity. This protein alteration, termed sulfhydration, has been observed in bacteria and mammalian cells, demonstrating its conservation throughout evolution, and therefore, highlighting its importance. Nothing is known about sulfhydration in fungal species, I will therefore investigate whether this protein alteration occurs in A. fumigatus and whether it is important for the fungus to grow within the lungs.I will use the gathered results to look for correlates between fungal and/or mammalian sulphur metabolism, and risk for aspergillosis. This will be achieved by interrogation of the human and fungal genome data curated by the University of Manchester. Importantly, these analyses may underscore relevant epidemiologic information which may aid patient management.