Abdelkrim Yosser Zina, Harigua-Souiai Emna, Barhoumi Mourad, Banroques Josette, Blondel Arnaud, Guizani Ikram, Tanner N Kyle
Expression Génétique Microbienne, CNRS UMR8261/Université Paris Diderot-Paris 7 & Paris Sciences et Lettres Research University, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France; Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis/Université de Tunis el Manar, 13 Place Pasteur, BP74 Tunis-Belvédère, 1002 Tunisia; Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna-Bizerte, Tunisia.
Molecular Epidemiology and Experimental Pathology (LR16IPT04), Institut Pasteur de Tunis/Université de Tunis el Manar, 13 Place Pasteur, BP74 Tunis-Belvédère, 1002 Tunisia.
Mol Biochem Parasitol. 2018 Dec;226:9-19. doi: 10.1016/j.molbiopara.2018.10.001. Epub 2018 Oct 23.
The antifungal agent 6-aminocholestanol targets the production of ergosterol, which is the principle sterol in many fungi and protozoans; ergosterol serves many of the same roles as cholesterol in animals. We found that it also is an effective inhibitor of the translation-initiation factor eIF4AI from mouse (eIF4AI) and the Trypanosomatid parasite Leishmania (LieIF4A). The eIF4A proteins belong to the DEAD-box family of RNA helicases, which are ATP-dependent RNA-binding proteins and RNA-dependent ATPases. DEAD-box proteins contain a commonly-shared core structure consisting of two linked domains with structural homology to that of recombinant protein A (RecA) and that contain conserved motifs that are involved in RNA and ATP binding, and in the enzymatic activity. The compound inhibits both the ATPase and helicase activities by perturbing ATP and RNA binding, and it is capable of binding other proteins containing nucleic acid-binding sites as well. We undertook kinetic analyses and found that the Leishmania LieIF4A protein binds 6-aminocholestanol with a higher apparent affinity than for ATP, although multiple binding sites were probably involved. Competition experiments with the individual RecA-like domains indicate that the primary binding sites are on RecA-like domain 1, and they include a cavity that we previously identified by molecular modeling of LieIF4A that involve conserved RNA-binding motifs. The compound affects the mammalian and Leishmania proteins differently, which indicates the binding sites and affinities are not the same. Thus, it is possible to develop drugs that target DEAD-box proteins from different organisms even when they are implicated in the same biological process.
抗真菌剂6-氨基胆甾烷醇作用于麦角甾醇的生成过程，麦角甾醇是许多真菌和原生动物中的主要甾醇；麦角甾醇在动物体内发挥着许多与胆固醇相同的作用。我们发现它还是小鼠翻译起始因子eIF4AI（eIF4AI）和锥虫寄生虫利什曼原虫（LieIF4A）的有效抑制剂。eIF4A蛋白属于DEAD-box RNA解旋酶家族，它们是依赖ATP的RNA结合蛋白和依赖RNA的ATP酶。DEAD-box蛋白包含一个共同的核心结构，由两个与重组蛋白A（RecA）结构同源的连接结构域组成，并且包含参与RNA和ATP结合以及酶活性的保守基序。该化合物通过干扰ATP和RNA结合来抑制ATP酶和螺旋酶活性，并且它还能够结合其他含有核酸结合位点的蛋白质。我们进行了动力学分析，发现利什曼原虫LieIF4A蛋白与6-氨基胆甾烷醇的结合亲和力高于与ATP的结合亲和力，尽管可能涉及多个结合位点。对单个RecA样结构域的竞争实验表明，主要结合位点在RecA样结构域1上，其中包括一个我们先前通过LieIF4A的分子建模确定的腔，该腔涉及保守的RNA结合基序。该化合物对哺乳动物和利什曼原虫的蛋白质影响不同，这表明结合位点和亲和力不同。因此，即使不同生物体中的DEAD-box蛋白参与相同的生物学过程，也有可能开发出针对它们的药物。
