Targeting methionine synthase in a fungal pathogen causes a metabolic imbalance that impacts cell energetics, growth and virulence-猫眼课题宝

DOI：

10.1101/2020.06.04.131862

发表时间：

2020-06

期刊：

bioRxiv

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

Jennifer Scott;Mónica Sueiro-Olivares;Benjamin P. Thornton;R. Owens;H. Muhamadali;Rachael Fortune-Grant;Darren D. Thomson;Riba Thomas;K. Hollywood;S. Doyle;R. Goodacre;L. Tabernero;E. Bignell;J. Amich

迫切需要开发新的抗真菌药物来解决真菌病原体对人类健康造成的威胁。在这项工作中，我们已经进行了全面的表征和验证的有前途的目标蛋氨酸合酶（MetH）。我们发现，在烟曲霉中，这种酶活性的缺乏会引发代谢失衡，导致细胞内ATP的减少，即使在甲硫氨酸的存在下也会阻止真菌生长。有趣的是，在某些代谢物的存在下，生长可以恢复，这证明metH是条件必需基因。由于这意味着为了正确验证MetH应该在已建立的感染中靶向，我们已经验证了tetOFF遗传模型用于真菌研究的用途，并优化了其性能以模拟已建立感染的治疗。我们表明，抑制生长菌丝中的metH在体外停止生长，这在体内使用该模型靶向已建立的感染时转化为有益效果。最后，甲硫氨酸脱氢酶的基于结构的虚拟筛选揭示了人类和真菌结构之间的关键差异，并揭示了真菌酶中可以指导新型特异性抑制剂设计的特征。因此，甲硫氨酸合酶是开发新的抗真菌药物的有价值的靶标。重要性真菌病原体是全球每年数百万威胁生命的感染的原因。目前的抗真菌药物非常有限，令人担忧的是，耐药性已经出现，并已成为我们治疗真菌疾病能力的严重威胁。开发新药的第一步通常是确定在感染期间抑制可以防止病原体生长的分子靶标。然而，目前的模型并不适合于在已建立的感染中验证靶标。在这里，我们的特点是有前途的抗真菌目标蛋氨酸合酶的非常详细，使用突出的真菌病原体烟曲霉作为模型。我们已经揭示了其重要性的根本原因，并证实了其可药用性。此外，我们已经优化了遗传系统的使用，以显示在已建立的感染中靶向甲硫氨酸合酶的有益效果。因此，我们认为，抗真菌药物的目标甲硫氨酸合酶应追求，此外，我们建议，抗真菌药物的目标应在一个已建立的感染模型进行验证。

There is an urgent need to develop novel antifungals to tackle the threat fungal pathogens pose to human health. In this work, we have performed a comprehensive characterisation and validation of the promising target methionine synthase (MetH). We uncover that in Aspergillus fumigatus the absence of this enzymatic activity triggers a metabolic imbalance that causes a reduction in intracellular ATP, which prevents fungal growth even in the presence of methionine. Interestingly, growth can be recovered in the presence of certain metabolites, which evidences that metH is a conditionally essential gene. As this implies that for a correct validation MetH should be targeted in established infections, we have validated the use of the tetOFF genetic model for fungal research and optimised its performance to mimic treatment of established infections. We show that repression of metH in growing hyphae halts growth in vitro, which translates into a beneficial effect when targeting established infections using this model in vivo. Finally, a structural-based virtual screening of methionine synthases reveals key differences between the human and fungal structures and unravels features in the fungal enzyme that can guide the design of novel specific inhibitors. Therefore, methionine synthase is a valuable target for the development of new antifungals. IMPORTANCE Fungal pathogens are responsible for millions of life-threatening infections on an annual basis worldwide. The current repertoire of antifungal drugs is very limited and, worryingly, resistance has emerged and already become a serious threat to our capacity to treat fungal diseases. The first step to develop new drugs often is to identify molecular targets which inhibition during infection can prevent pathogen growth. However, the current models are not suitable to validate targets in established infections. Here we have characterised the promising antifungal target methionine synthase in great detail, using the prominent fungal pathogen Aspergillus fumigatus as a model. We have uncovered the underlying reason for its essentiality and confirmed its druggability. Furthermore, we have optimised the use of a genetic system to show a beneficial effect of targeting methionine synthase in established infections. Therefore, we believe that antifungal drugs to target methionine synthase should be pursued and additionally, we propose that antifungal targets should be validated in a model of established infection.

Targeting methionine synthase in a fungal pathogen causes a metabolic imbalance that impacts cell energetics, growth and virulence

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