Direct Tests of Cytochrome Function in the Electron Transport Chain of Malaria Parasites.
Direct Tests of Cytochrome Function in the Electron Transport Chain of Malaria Parasites.
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疟疾寄生虫电子传递链中细胞色素功能的直接测试。
DOI：
10.1101/2023.01.23.525242
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Hill,Christophe
中科院分区：
文献类型：
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作者：
Espino-Sanchez,TanyaJ;Wienkers,Henry;Marvin,RebeccaG;Nalder,Shai-Anne;García-Guerrero,AldoE;VanNatta,PeterE;Jami-Alahmadi,Yasaman;Blackwell,AmandaMixon;Whitby,FrankG;Wohlschlegel,JamesA;Kieber-Emmons,MatthewT;Hill,Christophe
疟原虫疟原虫的线粒体电子传递链 (ETC) 是主要的抗疟药物靶点，但关键的细胞色素 (cyt) 功能仍未被研究且神秘。寄生虫表达两种不同的细胞同源物 (candc-2)，具有异常稀疏的序列同一性和不确定的适应性贡献。 falciparumcytc-2 是目前已知差异最大的真核细胞同源物，其序列特征预计与规范的 ETC 功能不相容。我们标记了 cytchomologs 和相关的 cytc1 以进行诱导性敲低。 cytcan 和 cytc1 的翻译抑制对寄生虫来说是致命的，寄生虫会因 ETC 功能障碍和泛醌回收受损而死亡。相比之下，cytc-2敲低或敲除对血期生长几乎没有影响，表明寄生虫完全依赖更保守的cytc来实现ETC功能。生化和结构研究表明，cytcandc-2 均被全细胞色素合酶半淀粉化，但 UV-vis 吸光度和 EPR 光谱强烈表明 cytc-2 具有异常开放的活性位点，其中血红素仅由单个轴向氨基酸配体稳定配位，并且可以结合外源小分子。这些研究对疟疾寄生虫 ETC 中的细胞色素功能进行了直接剖析，并鉴定了一种高度分化的细胞色素疟原虫，其分子适应性违背了真核进化中的保守作用。
The mitochondrial electron transport chain (ETC) ofPlasmodiummalaria parasites is a major antimalarial drug target, but critical cytochrome (cyt) functions remain unstudied and enigmatic. Parasites express two distinct cytchomologs (candc-2) with unusually sparse sequence identity and uncertain fitness contributions.P. falciparumcytc-2 is the most divergent eukaryotic cytchomolog currently known and has sequence features predicted to be incompatible with canonical ETC function. We tagged both cytchomologs and the related cytc1for inducible knockdown. Translational repression of cytcand cytc1was lethal to parasites, which died from ETC dysfunction and impaired ubiquinone recycling. In contrast, cytc-2 knockdown or knockout had little impact on blood-stage growth, indicating that parasites rely fully on the more conserved cytcfor ETC function. Biochemical and structural studies revealed that both cytcandc-2 are hemylated by holocytochromecsynthase, but UV-vis absorbance and EPR spectra strongly suggest that cytc-2 has an unusually open active site in which heme is stably coordinated by only a single axial amino acid ligand and can bind exogenous small molecules. These studies provide a direct dissection of cytochrome functions in the ETC of malaria parasites and identify a highly divergentPlasmodiumcytochromecwith molecular adaptations that defy a conserved role in eukaryotic evolution.