Identification and characterisation of UDP-galactofuranose transporter from the human pathogens Leishmania major and Aspergillus fumigatus

D-呋喃半乳糖（Galf）是一种不常见的半乳糖，存在于许多病原生物的细胞表面，包括细菌，真菌和原生动物，但不存在于哺乳动物中。Galf对于各种细菌的存活或毒力是必不可少的，参与其代谢途径的酶是开发新的抗菌药物的可行靶点。我们最近确定了第一个参与半乳糖苷合成的真核酶，UDP-吡喃半乳糖苷酶。我们目前的研究表明，它的致病性的利什曼原虫和烟曲霉提供了令人鼓舞的结果，在真核生物中的Galf代谢的化疗潜力。我们现在希望确定和验证Galf代谢的另一个关键参与者：UDP-Galf转运蛋白。核苷酸糖转运蛋白在结构上是保守的，可以很容易地从基因组数据库中识别;然而，它们的底物特异性无法预测。我们的方法将涉及候选核苷酸糖转运蛋白基因的选择和它们在真菌烟曲霉中的系统性缺失。然后，所需的突变体可用于鉴定主要利什曼原虫UDP-Galf转运蛋白。有了这个提议，我们希望进一步解开Galf在真核生物中的代谢。

The sugar D-galactofuranose (Galf) is an unusual form of galactose, present at the cell surface of many pathogenic organisms including bacteria, fungi and protozoa, but absent from mammals. Galf being essential for survival or virulence of various bacteria, the enzymes involved in its metabolic pathways are viable targets for the development of new antibacterial drugs. We recently identified the first eukaryotic enzyme involved in Galf biosynthesis, the UDP-galactopyranose mutase. Our current studies demonstrate its contribution to the pathogenicity of Leishmania major and Aspergillus fumigatus providing encouraging results for the chemotherapeutical potential of Galf metabolism in eukaryotes. We now wish to identify and characterise another key player of Galf metabolism: the UDP-Galf transporter. Nucleotide sugar transporters are structurally conserved and can be readily identified from genome databases; however their substrate specificity cannot be predicted. Our approach will involve the selection of candidate nucleotide sugar transporter genes and their systematic deletion in the fungus Aspergillus fumigatus. The desired mutant can then be used for the identification of Leishmania major UDP-Galf transporter. With this proposal, we wish to unravel further Galf metabolism in eukaryotes.