InBios/Phytosystems, Institut de Botanique, University of Liège, Liège, Belgium.
Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.
J Bioenerg Biomembr. 2021 Jun;53(3):351-363. doi: 10.1007/s10863-021-09882-8. Epub 2021 Mar 1.
In vivo associations of respiratory complexes forming higher supramolecular structures are generally accepted nowadays. Supercomplexes (SC) built by complexes I, III and IV and the so-called respirasome (I/III/IV) have been described in mitochondria from several model organisms (yeasts, mammals and green plants), but information is scarce in other lineages. Here we studied the supramolecular associations between the complexes I, III, IV and V from the secondary photosynthetic flagellate Euglena gracilis with an approach that involves the extraction with several mild detergents followed by native electrophoresis. Despite the presence of atypical subunit composition and additional structural domains described in Euglena complexes I, IV and V, canonical associations into III/IV, III/IV SCs and I/III/IV respirasome were observed together with two oligomeric forms of the ATP synthase (V and V). Among them, III/IV SC could be observed by electron microscopy. The respirasome was further purified by two-step liquid chromatography and showed in-vitro oxygen consumption independent of the addition of external cytochrome c.
目前，人们普遍认为呼吸复合物形成更高的超分子结构是在体内发生的。由复合物 I、III 和 IV 组成的超复合物（SC）和所谓的(respirasome)（I/III/IV）已在来自几种模式生物（酵母、哺乳动物和绿色植物）的线粒体中被描述，但在其他谱系中信息很少。在这里，我们研究了来自次生光合鞭毛生物 Euglena gracilis 的复合物 I、III、IV 和 V 之间的超分子相互作用，方法涉及用几种温和的去污剂提取，然后进行天然电泳。尽管 Euglena 的复合物 I、IV 和 V 中存在非典型的亚基组成和额外的结构域，但观察到了典型的 III/IV、III/IV SC 和 I/III/IV respirasome 以及两种寡聚形式的 ATP 合酶（V 和 V）。其中，III/IV SC 可以通过电子显微镜观察到。respirasome 进一步通过两步液相色谱法进行纯化，并显示体外耗氧量不依赖于外加细胞色素 c 的添加。
