Identification of a nitroimidazo-oxazine-specific protein involved in PA-824 resistance in Mycobacterium tuberculosis
Identification of a nitroimidazo-oxazine-specific protein involved in PA-824 resistance in Mycobacterium tuberculosis
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DOI：
10.1073/pnas.0508392103
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发表时间：
2006-01-10
影响因子：
11.1
通讯作者：
Barry, CE
中科院分区：
文献类型：
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作者：
Manjunatha, UH;Boshoff, H;Barry, CE
PA-824是一种很有前景的治疗结核病的新化合物，目前正在进行人体试验。与其前身甲硝唑和CGI-17341一样，PA-824是硝基咪唑类的前药，需要芳香硝基的生物还原活化才能发挥抗结核作用。我们已经证实，对PA-824（一种硝基咪唑-恶嗪）和gi -17341（一种硝基咪唑-恶唑）的抗性最常见的介导途径是特异性葡萄糖-6-磷酸脱氢酶（FGD1）或其去氮黄素辅因子F-420的丢失，它们共同为这类分子的还原激活提供电子。虽然FGD1和F-420对这些化合物的敏感性是必需的，但它们还不够，需要额外的辅助蛋白直接与硝基咪唑相互作用。为了了解更多与PA-824还原激活有关的事件，我们检测了FGD1和F420的野生型突变体，发现尽管这些突变体对PA-824（以及另一种硝基咪唑-恶唑）具有高水平的抗性，但它们对CGI-17341（以及相关的硝基咪唑-恶唑）保持敏感性。这些突变体基于微阵列的比较基因组测序发现了Rv3547的病变，Rv3547是一种未知功能的保守假设蛋白。与完整的Rv3547互补完全恢复了对硝基咪唑-恶嗪的敏感性，并恢复了Mtb代谢PA-824的能力。这些结果表明，Mtb对PA-824和相关化合物的敏感性是由一种蛋白质介导的，该蛋白质对这些双环硝基咪唑的细微结构变化具有高度特异性。
PA-824 is a promising new compound for the treatment of tuberculosis that is currently undergoing human trials. Like its progenitors metronidazole and CGI-17341, PA-824 is a prodrug of the nitroimidazole class, requiring bioreductive activation of an aromatic nitro group to exert an antitubercular effect. We have confirmed that resistance to PA-824 (a nitroimidazo-oxazine) and CGI-17341 (a nitroimidazo-oxazole) is most commonly mediated by loss of a specific glucose-6-phosphate dehydrogenase (FGD1) or its deazaflavin cofactor F-420, which together provide electrons for the reductive activation of this class of molecules. Although FGD1 and F-420 are necessary for sensitivity to these compounds, they are not sufficient and require additional accessory proteins that directly interact with the nitroimidazole. To understand more proximal events in the reductive activation of PA-824, we examined mutants that were wild-type for both FGD1 and F420 and found that, although these mutants had acquired high-level resistance to PA-824 (and another nitroimidazo-oxazine), they retained sensitivity to CGI-17341 (and a related nitroimidazo-oxazole). Microarray-based comparative genome sequencing of these mutants identified lesions in Rv3547, a conserved hypothetical protein with no known function. Complementation with intact Rv3547 fully restored sensitivity to nitroimidazo-oxazines and restored the ability of Mtb to metabolize PA-824. These results suggest that the sensitivity of Mtb to PA-824 and related compounds is mediated by a protein that is highly specific for subtle structural variations in these bicyclic nitroimidazoles.