Characterization of Trypanosoma brucei dihydroorotate dehydrogenase as a possible drug target;: structural, kinetic and RNAi studies
Characterization of Trypanosoma brucei dihydroorotate dehydrogenase as a possible drug target;: structural, kinetic and RNAi studies
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DOI：
10.1111/j.1365-2958.2008.06131.x
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发表时间：
2008-04-01
影响因子：
3.6
通讯作者：
Merritt, Ethan A.
中科院分区：
文献类型：
--
作者：
Arakaki, Tracy L.;Buckner, Frederick S.;Merritt, Ethan A.
据报道，核苷酸生物合成途径在一些原生动物病原体中是必不可少的。因此，我们通过基因敲低研究评估了一种酶在嘧啶生物合成途径中的重要性，即来自真核寄生虫布鲁氏锥虫的二氢羟酸脱氢酶（DHODH）。RNAi敲低布鲁氏体血液中DHODH的表达不会抑制正常培养基中的生长，但在嘧啶缺失培养基或已知嘧啶摄取拮抗剂5-氟尿嘧啶（5-FU）存在的情况下，会严重阻碍生长。这些结果对开发抗布鲁氏杆菌感染的治疗方法具有重要意义。具体来说，包括布鲁氏t -特异性DHODH抑制剂和5-FU的联合治疗可能是一种有效的治疗策略。我们还发现，这种锥虫酶被已知的1A类细菌DHODH抑制剂所抑制，这与人类和其他高等真核生物对DHODH的敏感性不同。这种选择性是由布鲁氏酵素的晶体结构支持的，在这里以1.95埃的分辨率报道。在本文描述的晶体结构的指导下，需要进一步的研究来确定布鲁氏T. DHODH的有效抑制剂。
Nucleotide biosynthesis pathways have been reported to be essential in some protozoan pathogens. Hence, we evaluated the essentiality of one enzyme in the pyrimidine biosynthetic pathway, dihydroorotate dehydrogenase (DHODH) from the eukaryotic parasite Trypanosoma brucei through gene knockdown studies. RNAi knockdown of DHODH expression in bloodstream form T. brucei did not inhibit growth in normal medium, but profoundly retarded growth in pyrimidine-depleted media or in the presence of the known pyrimidine uptake antagonist 5-fluorouracil (5-FU). These results have significant implications for the development of therapeutics to combat T. brucei infection. Specifically, a combination therapy including a T. brucei-specific DHODH inhibitor plus 5-FU may prove to be an effective therapeutic strategy. We also show that this trypanosomal enzyme is inhibited by known inhibitors of bacterial Class 1A DHODH, in distinction to the sensitivity of DHODH from human and other higher eukaryotes. This selectivity is supported by the crystal structure of the T. brucei enzyme, which is reported here at a resolution of 1.95 angstrom. Additional research, guided by the crystal structure described herein, is needed to identify potent inhibitors of T. brucei DHODH.