Toxoplasma gondii is a widely distributed apicomplexan parasite causing toxoplasmosis, a critical health issue for immunocompromised individuals and for congenitally infected foetuses. Current treatment options are limited in number and associated with severe side effects. Thus, novel anti-toxoplasma agents need to be identified and developed. 1-Deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) is considered the rate-limiting enzyme in the non-mevalonate pathway for the biosynthesis of the isoprenoid precursors isopentenyl pyrophosphate and dimethylallyl pyrophosphate in the parasite, and has been previously investigated for its key role as a novel drug target in some species, encompassing Plasmodia, Mycobacteria and Escherichia coli. In this study, we present the first crystal structure of T. gondii DXR (TgDXR) in a tertiary complex with the inhibitor fosmidomycin and the cofactor NADPH in dimeric conformation at 2.5 Å resolution revealing the inhibitor binding mode. In addition, we biologically characterize reverse α-phenyl-β-thia and β-oxa fosmidomycin analogues and show that some derivatives are strong inhibitors of TgDXR which also, in contrast with fosmidomycin, inhibit the growth of T. gondii in vitro. Here, ((3,4-dichlorophenyl)((2-(hydroxy(methyl)amino)-2-oxoethyl)thio)methyl)phosphonic acid was identified as the most potent anti T. gondii compound. These findings will enable the future design and development of more potent anti-toxoplasma DXR inhibitors.

中文翻译：

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1-脱氧-d-木酮糖 5-磷酸还原异构酶作为抗弓形虫药物的靶标：抑制剂的晶体结构、生化表征和生物学评价。


弓形虫是一种广泛分布的顶复门寄生虫，可引起弓形虫病，对于免疫功能低下的个体和先天感染的胎儿来说，弓形虫病是一个严重的健康问题。目前的治疗选择数量有限，并且伴有严重的副作用。因此，需要鉴定和开发新型抗弓形虫剂。 1-脱氧-d-木酮糖 5-磷酸还原异构酶 (DXR) 被认为是寄生虫中类异戊二烯前体异戊烯基焦磷酸和二甲基烯丙基焦磷酸生物合成非甲羟戊酸途径中的限速酶，之前已对其进行了研究在某些物种中作为新药物靶点发挥着关键作用，包括疟原虫、分枝杆菌和大肠杆菌。在这项研究中，我们以 2.5 Å 的分辨率展示了弓形虫 DXR (TgDXR) 与抑制剂福米霉素和辅因子 NADPH 形成的三级复合物的第一个晶体结构，其分辨率为 2.5 Å，揭示了抑制剂的结合模式。此外，我们对反向 α-苯基-β-硫杂和 β-oxa 磷米霉素类似物进行了生物学表征，并表明一些衍生物是 TgDXR 的强抑制剂，与磷米霉素相比，它还可以在体外抑制弓形虫的生长。在此，((3,4-二氯苯基)((2-(羟基(甲基)氨基)-2-氧代乙基)硫代)甲基)膦酸被确定为最有效的抗弓形虫化合物。这些发现将使未来设计和开发更有效的抗弓形虫 DXR 抑制剂成为可能。